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Water Quality Information Center of the National Agricultural Library Agricultural Research Service, U.S. Department of Agriculture

Simulation Models, GIS and Nonpoint-Source Pollution (I)

January 1991 - December 1993 Quick Bibliography Series: QB 94-06 (Updates QB 92-69) 337 citations from AGRICOLA Joe Makuch and Bonnie Emmert Water Quality Information Center Quick Bibliography Series Bibliographies in the Quick Bibliography series of the National Agricultural Library (NAL), are intended primarily for current awareness, and as the title of the series implies, are not in-depth and exhaustive. However, the citations are a substantial resource for recent investigations on a given topic. They also serve the purpose of bringing the literature of agriculture to the interested user who, in many cases, could not access it by any other means. The bibliographies are derived from online searches of the AGRICOLA database. Timeliness of topic and evidence of extensive interest are the selection criteria. Send suggestions for Quick Bibliography topics to wqic@nalusda.gov The author/searcher determines the purpose, length, and search strategy of the Quick Bibliography. Information regarding these is available from the author/searcher. The inclusion or omission of a particular publication or citation should not be construed as endorsement or disapproval. An author and subject index is provided along with the search strategy. PLEASE NOTE: If Quick Bibliography files are copied and/or distributed, please include in all copies the information regarding document delivery services and interlibrary loan requests found at the end of this file. The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, national origin, sex, religion, age, disability, political beliefs, and marital or familial status. (Not all prohibited bases apply to all programs). Persons with disabilities who require alternative means for communication of program

information (braille, large print, audiotape, etc.) should contact the USDA Office of Communications at (202) 720-5881 (voice) or (202) 720-7808 (TDD). To file a complaint, write the Secretary of Agriculture, U.S. Department of Agriculture, Washington, D.C. 20250, or call (202) 720-7327 (voice) or (202) 720-1127 (TDD). USDA is an equal employment opportunity employer. Simulation Models, GIS and Nonpoint-Source Pollution 1 NAL Call. No.: 56.8 SO3 An accurate and numerically stable model for one-dimensional solute transport in soils. Moldrup, P.; Yamaguchi, T.; Hansen, J.A.; Rolston, D.E. Baltimore, Md. : Williams & Wilkins; 1992 Apr. Soil science v. 153 (4): p. 261-273; 1992 Apr. Includes references. Language: English Descriptors: Soil solution; Solutes; Transport processes; Simulation models; Mathematical models; Soil water movement; Convection; Dispersion; Comparisons; Accuracy; Soil testing; Soil water content; Loam soils 2 NAL Call. No.: QH540.N3 Adsorption-desorption methodologies and selected estimation techniques for transport-modeling parameters. Roy, W.R. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p. 169-188; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Soil pollution; Pollutants; Adsorption; Desorption; Transport processes; Computer simulation; Vapor; Organic compounds; Volatilization; Groundwater pollution; Trichloroethylene; Microbial degradation 3 NAL Call. No.: HD1773.A2N6 Aggregate analysis of site-specific pollution problems: the case of groundwater contamination from agriculture. Opaluch, J.J.; Segerson, K. Morgantown, W.Va. : The Northeastern Agricultural and Resource Economics Association; 1991 Apr. Northeastern journal of agricultural and resource economics v. 20 (1): p. 83-97; 1991 Apr. Paper submitted in response to call for papers on the theme "The Effects of Agricultural Production on Environmental Quality.". Includes references.

Language: English Descriptors: Groundwater; Contamination; Water pollution; Agricultural sector; Agricultural policy; Microeconomic analysis; Aggregate data; Site factors; Spatial distribution; Information systems; Mathematical models 4 NAL Call. No.: S900.R39 Analysing water quality policy using microeconomic models of production practices and biophysical flow models of environmental processes. Weaver, R.D.; Harper, J.K. London : Harwood Academic Publishers; 1993. Resource management and optimization v. 9 (2): p. 95-105; 1993. Includes references. Language: English Descriptors: U.S.A.; Water quality; Water policy; Microeconomics; Technology; Environmental factors; Mathematical models 5 NAL Call. No.: 292.8 W295 An analytical solution for one-dimensional transport in porous media with an exponential dispersion function. Yates, S.R. Washington, D.C. : American Geophysical Union; 1992 Aug. Water resources research v. 28 (8): p. 2149-2154; 1992 Aug. Includes references. Language: English Descriptors: Transport processes; Solutes; Hydrodynamic dispersion; Subsurface layers; Equations; Mathematical models Abstract: An analytical solution describing the transport of dissolved substances in heterogeneous porous media with an asymptotic distance-dependent dispersion relationship has been developed. The solution has a dispersion function which is linear near the origin (i.e., for short travel distances) and approaches an asymptotic value as the travel distance becomes infinite. This solution can be used to characterize differences in the transport process relative to both the classical convection-dispersion equation which assumes that the hydrodynamic dispersion in the porous medium remains constant and a dispersion solution which has a strictly linear dispersion function. The form of the hydrodynamic dispersion function used in the analytical solution is D(x) = alpha(x) average pore water velocity + D(diff), where a(x) = a L[1 -e(- bx/L)]. The proposed model may provide an alternate means for obtaining a description of the transport of solutes in heterogeneous porous media, when the scale dependence of the dispersion relationship follows the behavior given by alpha(x). The overall behavior of the model is illustrated by several examples for constant concentration and flux boundary

conditions. 6 NAL Call. No.: 56.9 SO3 Analytical solution of solute diffusion and biodegradation in spherical aggregates. Priesack, E. Madison, Wis. : The Society; 1991 Sep. Soil Science Society of America journal v. 55 (5): p. 1227-1230; 1991 Sep. Includes references. Language: English Descriptors: Microbial degradation; Soil flora; Organic compounds; Solutes; Diffusion; Soil solution; Aggregates; Spatial distribution; Mathematical models; Soil pore system; Pores; Transport processes; Movement in soil; Diffusivity; Growth rate; Adsorption; Biomass; Substrates Abstract: Microbial degradation and transformation of substances in soils plays a crucial role ii the nutrient turnover of ecosystems. To quantify these processes, a mathematical description is needed. For this purpose, an analytical solution to a model of solute diffusion and biodegradation in soil aggregates was developed. The model is a first approach toward understanding the influence of geometric arrangement of microorganisms and substrates in structured soils. These soils are considered to consist of uniformly sized and shaped aggregates surrounded by surface films of the soil solution. The model simulates transient diffusion of finite substrate amounts from the surface films into spherical aggregates. Biodegradation is considered for the special case of unlimited microbial growth, and adsorption is assumed to follow a linear Freundlich isotherm. The system is represented by a composite sphere, the outer sphere being the solution film and the inner sphere representing the soil aggregate. The diffusion equations are solved by Laplace transformation. The model solution gives a direct relationship between the initial substrate and biomass concentrations, the diffusion coefficient, the specific growth rate, and the adsorption coefficient. Good agreement between this closed form solution and numerical solutions is obtained for diffusion with and without biodegradation. Since the substrate is exhausted by organisms close to the surface, the centers of large aggregates are not reached by the diffusing substrate. These unaffected centers become lager as the growth rate is higher, the diffusion constant is lower, and adsorption of the substrate is stronger. 7 NAL Call. No.: 292.8 W295 Analytical solutions for solute transport in three-dimensional semi-infinite porous media. Leij, F.J.; Skaggs, T.H.; Van Genuchten, M.T. Washington, D.C. : American Geophysical Union; 1991 Oct. Water resources research v. 27 (10): p. 2719-2733; 1991 Oct. Includes references.

Language: English Descriptors: Transport processes; Solutes; Flow; Mathematical models; Prediction Abstract: This paper presents several analytical solutions for three-dimensional solute transport in semi-infinite porous media with unidirectional flow using first-type (or concentration) and third-type (or flux) boundary conditions at the inlet location of the medium. The solutions may be used for predicting solute concentrations in homogeneous media, verification of more comprehensive numerical models, and laboratory or field determination of solute transport parameters. The transport equation incorporates terms accounting for advection, dispersion, zero-order production, and first-order decay. General solutions were derived for an arbitrary initial distribution and solute input with the help of Laplace, Fourier, and Hankel transforms. Specific solutions are presented for rectangular and circular solute inflow regions, as well as for solutes initially present in the form of parallelepipedal or cylindrical regions of the medium. The solutions were mathematically verified against simplified analytical solutions. Examples of concentration profiles are presented for several solute transport parameters using both first- and third-type boundary conditions. A mass balance constraint is defined based on a prescribed solute influx; the third-type condition is shown to conserve mass whereas the first-type condition was found to always overestimate resident solute concentrations in the medium. 8 NAL Call. No.: 292.8 W295 Applicability of the steady state flow assumption for solute advection in field soils. Destouni, G. Washington, D.C. : American Geophysical Union; 1991 Aug. Water resources research v. 27 (8): p. 2129-2140; 1991 Aug. Includes references. Language: English Descriptors: Agricultural soils; Solutes; Transport processes; Transient flow; Soil water movement; Soil texture; Soil depth; Plant water relations; Simulation models Abstract: A comparison between solute travel times predicted by a transient and a steady state flow model is made. Data for five different soil profiles with detailed measurements of their hydraulic properties and their variation with depth are used. Daily measurements of meteorological data are used as input parameters in the transient simulations that include snow and frost dynamics, interception of precipitation, and evapotranspiration. The parameters of the steady state flow model are related to the measured soil properties and the hydrological characteristics of each transient simulation. Furthermore, the influence of solute injection time on the

predicted travel time is analyzed, and the effect of root water uptake on the applicability, of the steady state flow assumption for solute advection is investigated. The results indicate that the steady, state flow model may provide estimates of the mean solute advection that are compatible with those of the transient flow model. The constant rate of recharge in the steady state flow, model should then be interpreted as the average annual effective infiltration (i.e., infiltration minus actual evapotranspiration). When root water uptake is accounted for, an arithmetic depth- averaging of the soil parameters appears to yield steady state estimates of arrival time that are closest to the transient predictions. When root water uptake is neglected, a harmonic depth-averaging of the soil parameters provides the best steady state results. The discrepancy between the arrival times predicted with the two flow models decreases with the travel distance from the soil surface. 9 NAL Call. No.: 100 G29So no.372 Application and enhancement of hydrologic/water quality models.. S-211 final report Thomas, Daniel L.; Shirmohammadi, Adel,_1952-; Engel, Bernard A. Tifton, Ga. : Biological and Agricultural Engineering Dept. : University of Georgia-Coastal Plain Experiment Station,; 1992. xi, 114 p. : ill. ; 28 cm. (Southern cooperative series bulletin ; no. 372). Running title: S-211 final report. June, 1992. Includes bibliographical references. Language: English; English Descriptors: Hydrology; Water quality 10 NAL Call. No.: SB951.P47 Application and validation of pesticide leaching models. Klein, M. Essex : Elsevier Applied Science Publishers; 1991. Pesticide science v. 31 (3): p. 389-398; 1991. Includes references. Language: English Descriptors: German federal republic; Bentazone; Cloethocarb; Simulation models; Environmental factors; Leaching; Lysimeters; Pesticide residues; Soil properties; Climatic factors Abstract: Two lysimeter studies with the pesticides cloethocarb and bentazone were used to validate a modified version of the computer model SESOIL (Seasonal Soil Compartment Model), developed by Bonazountas and Wagner and to transfer the results of the lysimeter study to another climate scenario. For cloethocarb, an experimental insecticide without marked mobility in the soil, as indicated by the lysimeter study, the simulations were in excellent agreement with the

lysimeter study. Calculations for bentazone revealed higher leaching than found in the lysimeter study. This discrepancy was resolved by a more careful and realistic inclusion of sorption in the lysimeter soil into the simulation model. 11 NAL Call. No.: 292.8 J82 An application of a physically based semi-distributed model to the Balquhidder catchments. Robson, A.J.; Whitehead, P.G.; Johnson, R.C. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 May15. Journal of hydrology v. 145 (3/4): p. 357-370; 1993 May15. Special Issue: The Balquhidder Catchment and Process Studies / edited by P.G. Whitehead and I.R. Calder. Includes references. Language: English Descriptors: Scotland; Watersheds; Simulation models; Catchment hydrology; Rain; Runoff; Flow Abstract: A physically based semi-distributed model, TOPMODEL, is applied to the two catchments at Balquhidder. The model uses a topographic index which highlights hydrologically significant areas within the catchments. The model is used to simulate runoff and to compare the behaviour of the two catchments. The results indicate that a large proportion of stream water is generated from saturated contributing areas (source areas); the Monachyle has higher contributions of water of this type. The results may also indicate that the hydrology of the Monachyle catchment has changed following agricultural improvement by increased drainage; a damped subsurface response is observed. 12 NAL Call. No.: QA76.76.E95A5 Application of case-based reasoning concepts to the WEPP soil erosion model. Meyer, C.R.; Flanagan, D.C. Moscow, Idaho : AI Applications; 1992. AI applications v. 6 (3): p. 63-71; 1992. Includes references. Language: English Descriptors: U.S.A.; Water erosion; Prediction; Simulation models; Information retrieval; Usda; Improvement; Management; Practice; Information storage; Data banks; Program development; Computer techniques 13 NAL Call. No.: 56.9 SO3 Applications of a laser scanner to quantify soil microtopography. Huang, C.H.; Bradford, J.M. Madison, Wis. : The Society; 1992 Jan. Soil Science Society of America journal v. 56 (1): p. 14-21; 1992 Jan. Includes references.

Language: English Descriptors: North Carolina; Hapludults; Inceptisols; Surface roughness; Measurement; Quantitative techniques; Surface layers; Topography; Height; Spatial variation; Mathematical models; Mathematics; Transport processes; Soil boundaries; Artificial precipitation; Tillage; Interrill erosion; Soil water content; Size; Lasers Abstract: Many transport processes on or across the soil surface boundary are controlled by surface microtopography, or roughness. How roughness affects the transport process depends on the length scale of the process. The most commonly used method of expressing soil surface roughness, the roughness length or random roughness, is constrained by the measurement technique and does not embody the concept of scale. The structural function, or variogram, plotted on a log-log scale was used in this study to express the surface roughness at different scales. With the aid of a laser scanner, surface topography was measured down to 0.5-mm grid spacing. Data collected from a variety of surface conditions showed that soil roughness can be quantified by a combination of fractal and Markov-Gaussian processes at different scales. Potential applications of the roughness quantification were also discussed. 14 NAL Call. No.: TD426.J68 An approach to estimating uncertainties in modeling transport of solutes through soils. Zhang, H.; Haan, C.T.; Nofziger, D.L. Amsterdam : Elsevier; 1993 Feb. Journal of contaminant hydrology v. 12 (1/2): p. 35-50; 1993 Feb. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Pollutants; Chemicals; Solutes; Movement in soil; Uncertainty; Rain; Variation; Prediction; Simulation models 15 NAL Call. No.: 292.8 W295 Approximate analytical solution for soil chemical transfer to runoff: a modified boundary condition. Wallach, R. Washington, D.C. : American Geophysical Union; 1993 May. Water resources research v. 29 (5): p. 1467-1474; 1993 May. Includes references. Language: English Descriptors: Agricultural chemicals; Soil solution; Surface water; Runoff water; Overland flow; Boundaries; Transport processes; Equations; Mathematical models; Comparisons Abstract: Two mass balance equations were used to model the

transfer of dissolved chemicals from the soil solution to the surface runoff water and the transport of these chemicals to the field outlet. One mass balance equation was written for chemicals dissolved in the overland water, the other for chemicals within the soil profile. Chemical input into the surface water (upper boundary condition) was expressed as a rate-limited convective mass transfer, depending on both soil surface and runoff concentrations. Isolating a slow and fast time scale and scaling the mass balance equations to the slow one yielded a parameter, epsilon, which multiplies the time derivative of the mass balance equation written for overland flow. In most cases epsilon << 1, providing a singular perturbation problem that was solved by using the method of matched asymptotic expansion. The approximate solution, uniformly valid over the entire domain, was made up of two terms: a leading-order solution and a first-order solution, the latter of which was relatively small, even for epsilon = O(1). The leading-order solution was compared with that for a simpler case, in which the convective mass transfer (upper boundary condition) depends only on the soil surface concentration. The comparison indicated those limited cases to which the simpler boundary condition can be applied resulting in a very small error. Although it is not possible to get a strictly analytical solution for a problem involving a modified upper boundary condition, the approximate analytical solution is easily obtained. 16 NAL Call. No.: 292.9 AM34 Assessing ground water pollution potential from nitrogen fertilizer using a geographic information system. Halliday, S.L.; Wolfe, M.L. Bethesda, Md. : American Water Resources Association; 1991 Mar. Water resources bulletin v. 27 (2): p. 237-245; 1991 Mar. Includes references. Language: English Descriptors: Texas; Groundwater pollution; Nitrogen fertilizers; Pollutants; Susceptibility; Expert systems Abstract: A geographic information system (GRASS 3.1) was used to correlate the availability of nitrogen fertilizer with the susceptibility of ground water to pollution in Texas to identify potential ground water quality problems. An agricultural pollution susceptibility map, produced by the Texas Water Commission using the DRASTIC methodology, was combined with information on cropped areas, recommended nitrogen fertilizer application rates, and aquifer outcrops. A Nitrogen Fertilizer Pollution Potential Index was generated, identifying 24 percent or Texas within the high pollution potential category. An analysis of the susceptibility of major aquifer outcrops to potential pollution from nitrogen fertilizer indicated that 34 percent of the outcrop areas fall in the high pollution potential range. It is proposed that correlating the availability of a pollutant with an assessment of the susceptibility of ground water to pollution yields a

more accurate screening tool for identifying potential pollution problems than considering susceptibility alone. 17 NAL Call. No.: S542.A8A34 Assessment and alleviation of the impact of runoff and erosion on crop production. Okwach, G.E.; Williams, J.; Wambua, J. Canberra : Australian Centre for International Agricultural Research; 1992. ACIAR proceedings (41): p. 72-82; 1992. In the series analytic: A search for strategies for sustainable dryland cropping in semi-arid eastern Kenya / edited by M.E. Probert. Paper presented at a symposium held Dec 10-11, 1990, Nairobi, Kenya. Includes references. Language: English Descriptors: Kenya; Runoff; Erosion; Soil fertility; Tillage; Mulches; Soil conservation; Semiarid zones; Simulation models 18 NAL Call. No.: 292.8 J82 An assessment of the dynamic response characteristics of streamflow in the Balquhidder catchments. Jakeman, A.J.; Littlewood, I.G.; Whitehead, P.G. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 May15. Journal of hydrology v. 145 (3/4): p. 337-355; 1993 May15. Special Issue: The Balquhidder Catchment and Process Studies / edited by P.G. Whitehead and I.R. Calder. Includes references. Language: English Descriptors: Scotland; Watersheds; Stream flow; Catchment hydrology; Clearcutting; Afforestation; Rain; Runoff; Simulation models Abstract: The method of rainfall-runoff modelling and hydrograph separation developed in an earlier paper is applied to the Kirkton and Monachyle catchments situated near Balquhidder, Scotland. Using daily rainfall and streamflow data, natural differences between the quick and slow flow responses for the Kirkton and Monachyle catchments are quantified, and an attempt is made to detect the impact of land-use changes on these natural regimes (clear-felling in part of the Kirkton and drainage ditching and conifer planting in part of the Monachyle). Dynamic response characteristics for the quick and slow flow components are defined in terms of time constants, relative throughput volumes and unit hydrograph peaks. These response characteristics are estimated and compared for annual periods before and after the land-use changes. For both the Kirkton and Monachyle, the effects of the land-use changes (affecting part of each catchment) on the hydrological response are not detectable at the catchment outlets. The interannual variation of the dynamic response characteristics falls within the inherent uncertainty expected if no land-use changes had occurred.

19 NAL Call. No.: aS21.A8U5/ARS Basin scale water quality model. Arnold, J.G. Washington, D.C. : The Service; 1993. Reprints - U.S. Department of Agriculture, Agricultural Research Service [512]: 9 p.; 1993. Indexed from reprint: Proceedings of the CREAMS and GLEAMS Conference. p. 192-200. Includes references. Language: English Descriptors: Catchment hydrology; Simulation models; Water quality; Climatic factors; Geological sedimentation; Runoff; Agricultural chemicals 20 NAL Call. No.: S612.I756 Best management of pesticide--furrow irrigation systems. Ranjha, A.Y.; Peralta, R.C.; Requena, A.M.; Deer, H.M.; Ehteshami, M.; Hill, R.W.; Walker, W.R. Berlin, W. Ger. : Springer International; 1992. Irrigation science v. 13 (1): p. 9-14; 1992. Includes references. Language: English Descriptors: Utah; Furrow irrigation; Design; Simulation models; Pesticides; Leaching; Losses from soil systems; Water management; Groundwater pollution; Soil texture Abstract: Effects of furrow irrigation designs, water management practices (irrigation scheduling, etc.), soil types and pesticide parameters on pesticide leaching were simulated. A hydraulic kinematic-wave irrigation model was used to estimate water infiltration for alternative furrow lengths and inflow rates. A one-dimensional simulation model then simulated the movement of pesticides through soils following furrow irrigation. Potential ground-water contamination by pesticides can be reduced by an integrated use of the best management practices (BMPs) such as careful selection and use of pesticides, efficient furrow irrigation designs and improved water management techniques (irrigation scheduling, etc.). Procedures for designing an appropriate furrow irrigation system for a particular site and pesticide, and selecting pesticides for a particular site, crop and furrow irrigation system are illustrated. These procedures are being used to develop decision support computer models for developing different BMPs for pesticide-agricultural management decisions. 21 NAL Call. No.: GB701.W375 no.91-4055 Calibration, verification, and use of a steady-state stream water-quality model for Monument and Fountain Creeks, east- central Colorado. Kuhn, Gerhard

Pikes Peak Area Council of Governments, Geological Survey (U.S.) Denver, CO : U.S. Dept. of the Interior, U.S. Geological Survey : Books and Open-File Reports Section [distributor],; 1991. vii, 149 p. : ill. ; 28 cm. (Water-resources investigations report ; 91-4055). Includes bibliographical references (p. 139-142). Language: English Descriptors: Water quality 22 NAL Call. No.: 290.9 AM32T Characterization of macropore transport studied with the ARS root zone water quality model. Ahuja, L.R.; DeCoursey, D.G.; Barnes, B.B.; Rojas, K.W. St. Joseph, Mich. : American Society of Agricultural Engineers; 1993 Mar. Transactions of the ASAE v. 36 (2): p. 369-380; 1993 Mar. Includes references. Language: English Descriptors: Macropores; Movement in soil; Root zone flux; Soil water; Water flow; Fertilizers; Pesticides; Simulation models Abstract: The ARS Root Zone Water Quality Model components dealing with preferential water and chemical transport are presented and used to study macropore flow and transport in a silty clay loam soil. Macroporosity of the soil was assumed to be 0.05% by volume, half of which was continuous and the rest discontinuous. Two rainfall sequences with two initial soil water contents, evaporation versus transpiration, macropore radius ranging from 1.0 to 0.125 mm, and three different chemicals were evaluated. Over a five-week period, weekly rainfall of 25.4 mm in one hour, with soil water redistribution and evaporation or transpiration occurring between storms, generated no macropore flow when the soil was initially dry (-1500 kPa). A slight amount of macropore flow was generated under the same rainfall when the soil was initially wet (-33 kPa). Doubling the weekly rainfall amount and intensity generated macropore flow varying between 30 to 50% of rainfall depending on initial and boundary conditions. Chemicals transported with this flow were 0.05 to 8% of the surface-applied amount, depending on conditions and type of chemical. A moderately adsorbed chemical (Atrazine) was the most susceptible to macropore transport, followed in order by a strongly adsorbed chemical (Prometryn), and a mobile chemical (Nitrate). The flow entering the macropores was partially absorbed by soil at progressively deeper depths; it increased the water content of the root zone, and created a tail of low concentrations in the soil chemical content distributions. The macropore size had very little effect on macropore flow and transport, but the smallest size pores retarded the downward chemical movement by wall adsorption a little more than the largest size pores. Surface evaporation

decreased macropore flow, soil water contents, and downward chemical movement, but increased chemical content of the macropore flow. Transpiration, on the other hand, decreased both macropore flow and its chemical content. Thu 23 NAL Call. No.: HC79.E5E5 Classification and spatial mapping of riparian habitat with applications toward management of streams impacted by nonpoint source pollution. Delong, M.D.; Brusven, M.A. New York, N.Y. : Springer-Verlag; 1991 Jul. Environmental management v. 15 (4): p. 565-571; 1991 Jul. Includes references. Language: English Descriptors: Idaho; Habitats; Riparian vegetation; Erosion; Pollution; Information systems; Mapping; Watersheds; Farmland 24 NAL Call. No.: 56.8 J822 Classifying remotely sensed data for use in an agricultural nonpoint-source pollution model. Jakubauskas, M.E.; Whistler, J.L.; Dillworth, M.E.; Martinko, E.A. Ankeny, Iowa : Soil and Water Conservation Society of America; 1992 Mar. Journal of soil and water conservation v. 47 (2): p. 179-183; 1992 Mar. Includes references. Language: English Descriptors: Kansas; Water quality; Water pollution; Remote sensing; Watersheds; Simulation models; Landsat; Thematic mapper; Data collection 25 NAL Call. No.: SB610.W39 Combining computer simulation with physical simulation: an attempt to validate turf runoff models. Lin, J.C.; Graney, R.L. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 688-695; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Agricultural chemicals; Pesticides; Simulation models; Runoff; Risk; Aquatic environment; Calibration; Field tests; Prediction 26 NAL Call. No.: 56.9 SO3 Comparison of models for describing the transport of dissolved organic carbon in aquifer columns. Jardine, P.M.; Dunnivant, F.M.; Selim, H.M.; McCarthy, J.F.

Madison, Wis. : The Society; 1992 Mar. Soil Science Society of America journal v. 56 (2): p. 393-401; 1992 Mar. Includes references. Language: English Descriptors: Aquifers; Sediment; Organic matter; Carbon; Transport processes; Adsorption; Sorption isotherms; Kinetics; Contaminants; Movement in soil; Mathematical models; Comparisons Abstract: Dissolved organic carbon (DOC) is a reactive constituent in aquifer and soil media and equilibrates between the mobile aqueous phase and the immobile solid phase. Since DOC is believed to accelerate the transport of associated contaminants, yet is known to interact with aquifer and soil material, our objective was to define and model those processes governing DOC adsorption to porous media that may affect the cotransport of contaminants. Column displacement experiments of DOC through aquifer sediments were modeled with various formulations of the convective-dispersive equation, which considered time-dependent adsorption reactions and linear or nonlinear adsorption processes. Batch equilibrium adsorption isotherm and kinetic studies for DOC interaction with the sediments were used to parameterize the transport models. The equilibrium DOC-adsorption isotherm was nonlinear and was adequately described by the Langmuir equation. The adsorption of DOC to the aquifer sediment was also time dependent and the batch results could be described by two simultaneous reaction rates for solution concentrations greater than or equal to 19 mg DOC L-1 and a slow reaction rate for solution concentrations < 10 mg DOC L-1. Observed DOC breakthrough curves (BTCs) with influent concentrations greater than or equal to 10 mg DOC L-1, were adequately modeled as two-site, non-linear adsorption processes, with DOC interactions with both types of sites being time dependent. Batch adsorption and kinetic parameters were generally successful in describing DOC transport; however, the magnitude of the initial batch rate coefficient was significantly larger than that observed for the displacement experiments. The extended tailing of the observed DOC BTCs was influenced more by the slow, time-dependent adsorption of DOC during transport than to the nonlinear features of the adsorption isotherms. Observed DOC BTCs with influent concentrations < 10 mg DOC L-1 did not exhibit extensive tailing and were 27 NAL Call. No.: QH545.A1E58 Comparison of PRZM and GLEAMS computer model predictions with field data for alachlor, metribuzin and norflurazon leaching. Mueller, T.C.; Jones, R.E.; Bush, P.B.; Banks, P.A. Elmsford, N.Y. : Pergamon Press; 1992. Environmental toxicology and chemistry v. 11 (3): p. 427-436; 1992. Includes references. Language: English

Descriptors: Alachlor; Norflurazon; Metribuzin; Herbicide residues; Leaching; Computer simulation; Simulation models; Soil depth; Sandy loam soils 28 NAL Call. No.: 292.8 J82 A comprehensive surface-groundwater flow model. Arnold, J.G.; Allen, P.M.; Bernhardt, G. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 Feb. Journal of hydrology v. 142 (1/4): p. 47-69; 1993 Feb. Includes references. Language: English Descriptors: Texas; Groundwater; Groundwater flow; Groundwater level; Surface water; Runoff; Flow; Stream flow; Watersheds; Catchment hydrology; Land management; Climate; Vegetation; Water management; Simulation models Abstract: In this study, a simple groundwater flow and height model was added to an existing basin-scale surface water model. The linked model is: (1) watershed scale, allowing the basin to be subdivided; (2) designed to accept readily available inputs to allow general use over large regions; (3) continuous in time to allow simulation of land management, including such factors as climate and vegetation changes, pond and reservoir management, groundwater withdrawals, and stream and reservoir withdrawals. The model is described, and is validated on a 471 km2 watershed near Waco, Texas. This linked model should provide a comprehensive tool for water resource managers in development and planning. 29 NAL Call. No.: 1.98 AG84 Computer model helps ensure clean water. Cooke, L. Washington, D.C. : The Service; 1991 Apr. Agricultural research - U.S. Department of Agriculture, Agricultural Research Service v. 39 (4): p. 10-12; 1991 Apr. Language: English Descriptors: Michigan; Groundwater pollution; Nitrates; Leaching; Prevention; Computer simulation; Computer techniques 30 NAL Call. No.: SB610.W39 Computer models for fate assessment during the registration process: data needs. Behl, E. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 696-700; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references.

Language: English Descriptors: Pesticides; Registration; Simulation models; Groundwater; Water quality 31 NAL Call. No.: GB701.W375 no.90-4200 Computer software for converting ground-water and water- quality data from the National Water Information System for use in a geographic information system.. Software for converting data from NWIS for use in GIS Scott, J. C. Geological Survey (U.S.) Oklahoma City, Okla. : U.S. Geological Survey ; Denver, Colo. : Books and Open-File Reports [distributor],; 1991. iv, 55 p. : ill. ; 28 cm. (Water-resources investigations report ; 90-4200). Spine title: Software for converting data from NWIS for use in GIS. Includes bibliographical references (p. 38-39). Language: English Descriptors: Geographic information systems; Water 32 NAL Call. No.: 290.9 AM32T Computing watershed storage probabilities from rainfall and runoff data. Mills, W.C.; Thomas, A.W.; Dillard, A.L.; Snyder, W.M. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 May. Transactions of the ASAE v. 35 (3): p. 891-897; 1992 May. Includes references. Language: English Descriptors: Rain; Runoff; Water conservation; Watersheds; Mathematical models; Probability Abstract: This article describes the development and application of a computational procedure for obtaining watershed storage probabilities that are corrected for bias toward lower storage, which is inherent in storage values computed directly from rainfall and runoff data. The developed procedure makes use of rainfall and runoff data from watersheds, and also incorporates probabilities for rainfall needed to produce runoff for various storages. The procedure is derived mathematically using basic probability concepts and employs numerical integration and nonlinear least squares optimization in the solution. The procedure is applied to rainfall and runoff data collected from a Southern Piedmont field watershed over a 10-year period during which a conventional tillage system for crops was followed by two successive conservation tillage systems. Results of the application show that the developed computational procedure performs adequately in providing bias-corrected watershed storage probabilities that reflect effects of the three cropping/tillage systems on watershed storage.

33 NAL Call. No.: TD426.J68 Conditional simulation of flow and transport. Rogowski, A.S.; Wolf, J.K.; Simmons, D.E. Amsterdam : Elsevier; 1991 Jan. Journal of contaminant hydrology v. 7 (1/2): p. 95-121; 1991 Jan. Includes references. Language: English Descriptors: Groundwater pollution; Leachates; Movement in soil; Groundwater recharge; Clay; Subsoil; Infiltration; Spatial distribution; Simulation models; Spatial variation 34 NAL Call. No.: aSD11.A42 The conservation reserve program: effects on soil, water and environmental quality. Blackburn, W.H.; Newman, J.B.; Wood, J.C. Fort Collins, Colo. : The Station; 1991 May. General technical report RM - Rocky Mountain Forest and Range Experiment Station, U.S. Department of Agriculture, Forest Service (203): p. 27-36; 1991 May. Includes references. Language: English Descriptors: U.S.A.; Soil conservation; Erosion control; Federal programs; Reserved areas; Simulation models; Percolation; Evapotranspiration; Water erosion; Runoff 35 NAL Call. No.: TD420.A1E5 Convective transport of gases in moist porous media: effect of absorption, adsorption, and diffusion in soil aggregates. McCoy, B.J.; Rolston, D.E. Washington, D.C. : American Chemical Society; 1992 Dec. Environmental science & technology v. 26 (12): p. 2468-2476; 1992 Dec. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Volatile compounds; Mathematical models 36 NAL Call. No.: TC401.W27 A coupled rainfall-runoff and runoff-routing model for adaptive real-time flood forecasting. Habaieb, H.; Troch, P.A.; Troch, F.P. de Hingham, Mass. : Kluwer Academic Publishers; 1991. Water resources management v. 5 (1): p. 47-61; 1991. Includes references. Language: English Descriptors: Belgium; Floods; Forecasting; Rain; Runoff;

Models; On line; Identification; Case studies 37 NAL Call. No.: 292.8 J82 Coupled simulations of water flow from a field-investigated glacial till slope using a quasi-two-dimensional water and heat model with bypass flow. Espeby, B. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Feb. Journal of hydrology v. 131 (1/4): p. 105-132; 1992 Feb. Includes references. Language: English Descriptors: Sweden; Glacial till soils; Forest soils; Coniferous forests; Picea abies; Pinus sylvestris; Slopes; Water flow; Macropore flow; Meltwater; Precipitation; Runoff; Soil water retention; Saturated hydraulic conductivity; Macropores; Soil temperature; Soil depth; Physical models; Simulation models Abstract: Substantial field investigations of soil physical properties and stratification in a forested slope (10 degrees slope) covered with glacial till revealed that macropores in the form of old root channels as well as coarse structures in the form of well-sorted layers dominate a very permeable upper solid horizon. Rapid response and quick recessions during snowmelt and heavy rains in 1986 were observed in the runoff from the slope. Based on field tracer experiments it was found that such macropores and macrostructures played an important role on these occasions. In order to verify these findings one-dimensional water and heat models were coupled in a serial manner to simulate the formation of runoff from the slope, using a quasi-two-dimensional approach. Both a strict Darcian concept and a Darcian concept with a simple bypass flow concept introduced were tested. The drainage gradient in the model was made equal with the angle of the slope. Coupled slope simulations, with water retention properties and hydraulic conductivities taken from three different levels on the slope, indicated that the conditions in the lower region of the slope were most important in explaining the discharge rate. With a shallow groundwater table in the lower region of the slope and low hydraulic conductivity of the deeper layers, rapid water flows are routed to the uppermost layers where the conductivity is higher. Most of the flow is well described by Richards' equation, although smaller peaks cannot be represented for small rain events, when the measured runoff and recession showed a more rapid response than that simulated, however, the introduction of a simple bypass flow improved the ability of the model to simulate the observations. Much of the simulated surface runoff generated in the Darcian simulation during the winter of 1986, could be diverted through a frost layer in the humus horizon and in the humus-impregnated mineral horizon with a silty-sand character, down to a more conductiv 38 NAL Call. No.: QH540.J6

Coupling groundwater contamination with economic returns when applying farm pesticides. Hoag, D.L.; Hornsby, A.G. Madison, Wis. : American Society of Agronomy; 1992 Oct. Journal of environmental quality v. 21 (4): p. 579-586; 1992 Oct. Includes references. Language: English Descriptors: North Carolina; Groundwater pollution; Methodology; Pesticides; Usage; Economic impact; Returns; Profitability; Environmental impact; Glycine max; Weed control; Costs; Crop yield; Weed competition; Leaching; Simulation models Abstract: A methodology is presented that permits simultaneous consideration of the economics of production and groundwater contamination hazard of pesticide use. An example is constructed for weed control in soybean (Glycine max L.) production at Clayton, NC. A cost/groundwater hazard frontier is developed that can be used to identify and illustrate the cost tradeoffs of selecting alternative weed control strategies that reduce the risk of adverse health effects from drinking contaminated groundwater. The methodology relies on models to estimate costs, crop yields, pest competition, and leaching of pesticides; thus, its applicability depends on availability of local data and appropriately validated models for the site considered. The cost/groundwater hazard frontier provides a useful decision aid to assist pesticide users in making cost-effective and environmentally favorable production decisions. It is also useful in evaluating policy or the value of new pest control technologies, as it indicates a farmer's ability to substitute alternatives for currently used practices. 39 NAL Call. No.: 381 J8224 Criteria to assess when biodegradation is kinetically limited by intraparticle diffusion and sorption. Chung, G.Y.; McCoy, B.J.; Scow, K.M. New York, N.Y. : John Wiley & Sons; 1993 Mar15. Biotechnology and bioengineering v. 41 (6): p. 625-632; 1993 Mar15. Includes references. Language: English Descriptors: Soil flora; Microbial degradation; Pollutants; Transport processes; Diffusion; Sorption; Desorption; Polluted soils; Soil pollution; Mathematical models; Bioremediation Abstract: To determine when intraparticle diffusion and sorption can influence the rate of biodegradation, we consider the biodegradation of a pollutant diffusing into or out of porous aggregates suspended in a liquid medium, where the reactant is metabolized by bacteria. The pollutant that diffuses into the aggregates obeys a sorption-desorption equilibrium isotherm at sites on inner pore surfaces. The

governing partial differential equations for the transient process describe (a) the local equilibrium sorption-desorption and the diffusion of the pollutant in the porous aggregate, (b) the mass transfer of the pollutant from the external surface of the spherical aggregates to the reaction medium, and (c) the biodegradation of the pollutant in the external medium. Illustrative calculations are presented for a linear sorption isotherm and first-order biodegradation kinetics. A dimensionless group, comprised of the diffusion coefficient, biodegradation rate coefficient, aggregate characteristic length (radius), and adsorption capacity, serves as a criterion for determining when intraparticle diffusion resistance can be ignored. The model provides a realistic description of experimental data for biodegradation of a pollutant subject to intraparticle diffusion and sorption. 40 NAL Call. No.: TD420.A1P7 DBAPE--a database and model parameter analysis system for agricultural soils to support water quality management. Imhoff, J.C.; Carsel, R.F.; Kittle, J.L. Jr; Hummel, P.R. Oxford : Pergamon Press; 1991. Water science and technology : a journal of the International Association on Water Pollution Research and Control v. 24 (6): p. 331-337; 1991. In the series analytic: Watermatex '91 / edited by T.O. Barnwell, P.J. Ossenbruggen and M.B. Beck. Proceedings of the "Second International Conference on Systems Analysis in Water Quality Management," June 3-6, 1991, Durham, New Hampshire. Includes references. Language: English Descriptors: Soil properties; Water quality; Management; Agricultural soils; Computer software; Subsurface runoff; Models; Databases 41 NAL Call. No.: QH540.J6 Degradation and transport of dicamba in a clay soil. Comfort, S.D.; Inskeep, W.P.; Macur, R.E. Madison, Wis. : American Society of Agronomy; 1992 Oct. Journal of environmental quality v. 21 (4): p. 653-658; 1992 Oct. Includes references. Language: English Descriptors: Dicamba; Clay soils; Degradation; Leaching; Soil water movement; Soil temperature; Persistence; Half life; Precipitation; Irrigation scheduling; Simulation models Abstract: Dicamba (3,6-dichloro-2-methoxybenzoic acid) has been identified as one of five pesticides present in Montana groundwaters. We determined the effects of degradation and time of water application on the transport of dicamba in a Lohmiller clay soil (fine, montmorillonitic, mesic Ustic Torrifluvent). Carbon 14-labeled dicamba was surface applied (0.35 kg ha-1) to disturbed soil columns (5.0 cm diam; 29 cm

length) previously conditioned with 3 mM CaCl2. The columns were allowed to incubate (23.5 degrees C) in triplicate for 0, 14, 21, 28, and 42 d. Following incubation, the columns were attached to a vacuum chamber containing a fraction collector and leached with 3 mM CaCl2 under unsaturated conditions. Dicamba breakthrough curves were determined for each incubation period. The percentage of dicamba recovered in the column effluent decreased from 85% (of total applied) after no incubation to 9.5% after 42 d of incubation. The decline of dicamba in the effluent coincided with an accumulation of dichlorosalicyclic acid at the soil surface. Dicamba half- lives determined under batch conditions were 23.5 d at 28 degrees C, 38 d at 20 degrees C, and 151 d at 12 degrees C, and were all higher than the half-life estimated from the decrease in column effluent concentrations over time (13.5 d). The simulation model, LEACHM, was used to predict transport of dicamba after the different incubation periods. LEACHM adequately estimated the mass of dicamba leached, but underestimated the maximum dicamba concentrations observed in the effluent. Both simulated and observed results indicated that the transport of dicamba can be greatly reduced if sufficient degradation of dicamba is allowed to occur before irrigation or precipitation. 42 NAL Call. No.: QC851.J62 A description of rainfall interception over large areas. Eltahir, E.A.B.; Bras, R.L. Boston, MA : American Meteorological Society, c1988-; 1993 Jun. Journal of climate v. 6. (6): p. 1002-1008; 1993 Jun. Includes references. Language: English Descriptors: Rain; Ground vegetation; Canopy; Drainage; Runoff water; Interception; Evaporation; Models; Climatic factors Abstract: A new scheme is developed for describing interception at spatial scales comparable to the typical resolution of climate models. The scheme is based on the Rutter model of interception and statistical description of the subgrid-scale spatial variability of canopy storage and rainfall. The interception loss simulated by the new scheme is significantly smaller than those simulated by other schemes that do not include considerations for spatial variability. The explanation of this result is partly in the enhancement of spatially averaged canopy drainage due to the large local drainage from the few buckets of large canopy storage. The relative reduction in interception loss simulated by the new scheme may explain the overestimation of interception loss by climate models that do not include the effects of spatial variability on interception processes. 43 NAL Call. No.: TD403.G7 Design and evaluation of a mesoscale model vadose zone and ground-water system.

Lawrence, J.R.; Zanyk, B.N.; Hendry, M.J.; Wolfaardt, G.M.; Robarts, R.D.; Caldwell, D.E. Dublin, Ohio : Ground Water Pub. Co; 1993 May. Ground water v. 31 (3): p. 446-455; 1993 May. Includes references. Language: English Descriptors: Groundwater pollution; Soil pollution; Contaminants; Movement in soil; Chemical degradation; Microbial degradation; Models; Agricultural chemicals Abstract: A mesoscale model soil and ground-water system was constructed and instrumented to study physical, chemical, and microbial processes, including transport and degradation of contaminants. The model system was 4.6 m in height by 2.4 m in diameter and contained up to 65 tonnes of soil and geologic materials. The model was filled with Ap (11 cm), B (20 cm), Cl and C2 (369 cm) horizons; the water table was 3.3 m from the soil surface. A rain simulation system applied uniform coverage of rain and/or chloride tracer to the model. Sampling of soil, sediment, pore waters, and gas phase was carried out using a series of in situ collectors and sampling ports. Major anions, metals, pH, alkalinity, CO2, N2, O2, CH4, microbial numbers, microbial biomass and heterotrophic potential (14 C- amino-acid uptake) were monitored over time (120 days) and depth. The system approached steady state with respect to solution chemistry and gases after approximately 60-70 days. During this interval, carbon dioxide rose from atmospheric to 3-5% of total gas volume measured at each sampling depth above the water table. Physical, chemical, and biological conditions in the model system after the initial 120 days were comparable to those reported for vadose and saturated zones during field studies on shallow phreatic aquifers. These results indicated that the mesoscale model preserved many of the features of natural systems while providing controlled conditions for studies such as evaluating the fate, and ground-water contamination potential, of agricultural and industrial chemicals. 44 NAL Call. No.: TD201.A4 Design of optimal pump-and-treat strategies of contaminated groundwater remediation using the simulated annealing algorithm. Kuo, C.H.; Michel, A.N.; Gray, W.G. Essex : Elsevier Science Publishers Ltd; 1992. Advances in water resources v. 15 (2): p. 95-105; 1992. Includes references. Language: English Descriptors: Groundwater pollution; Problem solving; Pumps; Placement; Optimization methods; Hydraulics; Constraints; Simulation models; Algorithms

45 NAL Call. No.: TD403.G7 Designing a nitrate monitoring program in a heterogeneous, carbonate aquifer. Smith, R.T.; Ritzi, R.W. Jr Dublin, Ohio : Ground Water Pub. Co; 1993 Jul. Ground water v. 31 (4): p. 576-584; 1993 Jul. Includes references. Language: English Descriptors: Ohio; Aquifers; Carbonates; Hydraulic conductivity; Finite element analysis; Simulation models; Nitrates; Movement in soil; Zea mays; Glycine max; Rotations; Groundwater pollution 46 NAL Call. No.: 292.9 AM34 Determination of best timing for poultry waste disposal: a modeling approach. Edwards, D.R.; Daniel, T.C.; Marbun, O. Bethesda, Md. : American Water Resources Association; 1992 May. Water resources bulletin v. 28 (3): p. 487-494; 1992 May. Includes references. Language: English Descriptors: Arkansas; Poultry manure; Waste disposal; Application to land; Application date; Timing; Surface water; Runoff water; Water quality; Nitrogen; Phosphorus; Losses from soil systems; Grasses; Crop production; Crop yield Abstract: Confined production of poultry results in significant volumes of waste material which are typically disposed of by land application. Concerns over the potential environmental impacts of poultry waste disposal have resulted in ongoing efforts to develop management practices which maintain high quality of water downstream of disposal areas. The timing of application to minimize waste constituent losses is a management practice with the potential to ensure high quality of streams, rivers, and lakes downstream of receiving areas. This paper describes the development and application of a method to identify which time of year is best, from the standpoint of surface water quality, for land application of poultry waste. The procedure consists of using a mathematical simulation model to estimate average nitrogen and phosphorus losses resulting from different application timings, and then identifying the timings which minimize losses of these nutrients. The procedure was applied to three locations in Arkansas, and three different criteria for optimality of application timing were investigated. One criterion was oriented strictly to water quality, one was oriented only to crop production, and the last was a combination. The criteria resulted in different windows of time being identified as optimal. Optimal windows also varied with location of the receiving area. The results indicate that it is possible to land-apply poultry waste at times which both minimize nutrient losses and maximize crop yield.

47 NAL Call. No.: SB951.P47 Development and validation of a modified fugacity model of pesticide leaching from farmland. Brooke, D.; Matthiessen, P. Essex : Elsevier Applied Science Publishers; 1991. Pesticide science v. 31 (3): p. 349-361; 1991. Includes references. Language: English Descriptors: England; Mecoprop; Simazine; Concentration; Leaching; Measurement; Models; Monitoring; Soil properties; Water pollution; Agricultural soils Abstract: To test whether a simple model could provide reasonable quantitative estimates of chemical concentrations in a dynamic situation, Mackay's fugacity model was adapted to represent an agricultural field. The intention was to determine the extent of modification required to obtain reasonable agreement with experimental results, or indeed if such agreement could be achieved. The validity of the model was tested at Rosemaund Experimental Husbandry Farm in Herefordshire, where the chemical input and output could be monitored and meteorological and other parameters measured regularly. Results from monitoring concentrations of two pesticides at this site in recent years. and changes that have been made to the model in attempting to fit the observed behaviour are described. 48 NAL Call. No.: QH540.J6 Development of a database and model parameter analysis system for agricultural soils. Carsel, R.F.; Imhoff, J.C.; Kittle, J.L. Jr; Hummel, P.R. Madison, Wis. : American Society of Agronomy; 1991 Jul. Journal of environmental quality v. 20 (3): p. 642-647; 1991 Jul. Includes references. Language: English Descriptors: Water quality; Water management; Databases; Computer software; Water flow Abstract: An interactive computer program was developed for obtaining soils data for geographic analyses and estimation of soil water retention data for simplistic and classical water flow models. The soils data base contains 8080 soil series identified from the USDA-SCS. The data are organized in sequential files that contain textural, morphological crop support, and geographical location (at a county level) and density (ha/county). The computer program allows the exploration of the database, clarifying the impact of data on modeled processes, screening geographically based data to identify potential sites for model application or testing, and developing initial guidance on alternative water quality management strategies. The program allows the display of data in the form of generated reports and production of geographic

maps and plots of soil water functional relationships. Indirect methods are used in the program for estimating soil water retention characteristics using textural information from the soil data base. Estimates of variability can be developed within a soil series or among series by using reported ranges for textural information on each series contained in the soil database. 49 NAL Call. No.: S592.7.A1S6 Dispersion effect on the apparent nitrogen isotope fractionation factor associated with denitrification in soil; evaluation by a mathematical model. Kawanishi, T.; Hayashi, Y.; Kihou, N.; Yoneyama, T.; Ozaki, Y. Exeter : Pergamon Press; 1993 Mar. Soil biology and biochemistry v. 25 (3): p. 349-354; 1993 Mar. Includes references. Language: English Descriptors: Denitrification; Quantitative analysis; Agricultural soils; Solutes; Dispersion; Transport processes; Soil water; Water flow; Mathematical models; Nitrate; Groundwater pollution Abstract: An analytical model is constructed to investigate the effect of dispersion on the apparent 15N/14N fractionation factor associated with denitrification in soil. The steady input of solute with a fixed isotope ratio, uniform flow of the solute, and the first-order reaction for each isotope are assumed, and the relationship between the concentration distribution and the change of isotope ratio in the steady state is examined. The only dimensionless parameter, kl4ND/v2, the product of the first-order reaction rate constant and the dispersion coefficient divided by the square of the superficial velocity, determines the effect of dispersion, and if its value is larger than 0.01, the dispersion will affect the apparent isotope fractionation factor. As kl4ND/v2 increases, the effect becomes more prominent, and when it approaches infinity, the ratio of the apparent per mille enrichment factor to the true one, (alpha ap-1)/(alpha tr-1), reaches 0.5. 50 NAL Call. No.: GB701.W375 no.93-4015 Documentation of geographic-information-system coverages and data-input files used for analysis of the geohydrology of the Virginia Coastal Plain.. Documentation of geographic information system coverages and data input files used for analysis of the geohydrology of the Virginia Coastal Plain Focazio, Michael J.; Samsel, Theodore B. Geological Survey (U.S.),Hampton Roads Planning District Commission (Va.),Virginia Water Control Board Richmond, Va. : U.S. Geological Survey ; Denver, CO : Books and Open-File Reports Section [distributor],; 1993; I 19.42/4:93-4015. vi, 53 p. : maps ; 28 cm. (Water-resources investigations

report ; 93-4015). Shipping list no.: 93-0451-P. Includes bibliographical references (p. 11). Language: English; English Descriptors: Hydrogeology; Geographic information systems 51 NAL Call. No.: 292.8 W295 A dual-porosity model for simulating the preferential movement of water and solutes in structured porous media. Gerke, H.H.; Van Genuchten, M.T. Washington, D.C. : American Geophysical Union; 1993 Feb. Water resources research v. 29 (2): p. 305-319; 1993 Feb. Includes references. Language: English Descriptors: Transport processes; Solutes; Water flow; Saturated flow; Transient flow; Leaching; Porous media; Physicochemical properties; Deterministic models; Mathematical models; Equations Abstract: A one-dimensional dual-porosity model has been developed for the purpose of studying variably saturated water flow and solute transport in structured soils or fractured rocks. The model involves two overlaying continua at the macroscopic level: a macropore or fracture pore system and a less permeable matrix pore system. Water in both pore systems is assumed to be mobile. Variably saturated water flow in the matrix as well as in the fracture pore system is described with the Richards' equation, and solute transport is described with the convection-dispersion equation. Transfer of water and solutes between the two pore regions is simulated by means of first-order rate equations. The mass transfer term for solute transport includes both convective and diffusive components. The formulation leads to two coupled systems of nonlinear partial differential equations which were solved numerically using the Galerkin finite element method. Simulation results demonstrate the complicated nature of solute leaching in structured, unsaturated porous media during transient water flow. Sensitivity studies show the importance of having accurate estimates of the hydraulic conductivity near the surface of soil aggregates or rock matrix blocks. The proposed model is capable of simulating preferential flow situations using parameters which can be related to physical and chemical properties of the medium. 52 NAL Call. No.: 100 C12CAG Dupuit-Forchheimer approximation may underestimate groundwater flow to San Joaquin River. Grismer, M.E.; Rashmawi, E.A. Oakland, Calif. : Division of Agriculture and Natural Resources, University of California; 1993 Jan. California agriculture v. 47 (1): p. 12, 13-15; 1993 Jan.

Language: English Descriptors: California; Groundwater flow; River water; Water quality; Water management; Salinity; Estimation; Water table; Errors; Mathematical models 53 NAL Call. No.: GB746.W33 Dynamic-probabilistic models for the formation of rainfall and snowmelt runoff. Kuchment, L.S.; Gel'fan, A.N. New York, N.Y. : Consultants Bureau; 1992 May. Water resources v. 18 (4): p. 335-343; 1992 May. Translated from: Vodnye Resursy, v. 18 (4), 1991, p. 5-14, (GB746.V55). Includes references. Language: English; Russian Descriptors: U.S.S.R.in europe; Rain; Meltwater; Floods; Runoff water; Watersheds; Forest steppe; Zoning; Probabilistic models; Dynamic models; Physical models; Mathematical models; Weather data 54 NAL Call. No.: HD101.S6 Economic impacts of chemical use reduction on the South. Taylor, C.R.; Penson, J.B. Jr; Smith, E.G.; Knutson, R.D. Experiment, Ga. : The Association; 1991 Jul. Southern journal of agricultural economics - Southern Agricultural Economics Association v. 23 (1): p. 15-23; 1991 Jul. Discussion by J.R. Schaub, p. 25-26. Includes references. Language: English Descriptors: Southern states of U.S.A.; Agricultural chemicals; Pesticide residues; Water quality; Groundwater; Contamination; Food safety; Agricultural policy; Models; Economic impact; Income 55 NAL Call. No.: HD1.A3 The economics of water harvesting and supplementary irrigation in the semi-arid tropics of India. Pandey, S. Essex : Elsevier Applied Science Publishers; 1991. Agricultural systems v. 36 (2): p. 207-220; 1991. Includes references. Language: English Descriptors: Madhya pradesh; Soybeans; Wheat; Water harvesting; Irrigation; Cropping systems; Semiarid zones; Agricultural regions; Economic evaluation; Feasibility; Risk; Simulation models; Soil water balance; Yield response functions; Water relations; Decision making; Rain; Runoff water

56 NAL Call. No.: 56.8 SO3 The effect of soil P sorption kinetics on parameters used for modeling P uptake. Shnek, M.; Shaviv, A.; Ravina, I. Baltimore, Md. : Williams & Wilkins; 1991 May. Soil science v. 151 (5): p. 333-342; 1991 May. Includes references. Language: English Descriptors: Calcareous soils; Soil physics; Phosphorus; Sorption; Kinetics; Diffusion models; Desorption; Mathematical models; Soil solution; Equilibrium; Buffering capacity; Nutrient uptake; Prediction; Equations; Solubility; Nutrient availability; Transport processes 57 NAL Call. No.: 56.8 SO3 The effect of soil properties on phosphorus sorption by everglades histosols. Porter, P.S.; Sanchez, C.A. Baltimore, Md. : Williams & Wilkins; 1992 Nov. Soil science v. 154 (5): p. 387-398; 1992 Nov. Includes references. Language: English Descriptors: Florida; Histosols; Agricultural soils; Phosphorus; Sorption; Movement in soil; Leaching; Losses from soil systems; Soil chemistry; Soil properties; Water pollution; Indexes; Models 58 NAL Call. No.: 292.8 J82 The effect of transverse dispersion on solute transport in soils. Leij, F.J.; Dane, J.H. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Jan. Journal of hydrology v. 122 (1/4): p. 407-422; 1991 Jan. Includes references. Language: English Descriptors: Solutes; Transport processes; Horizontal flow; Two dimensional flow; Transverse distribution; Permeability; Simulation; Mathematical models Abstract: Most theoretical and experimental investigations of solute transport involve one-dimensional problems (i.e. soil column studies), whereas in reality many soil pollution problems concern transport and flow in more than one dimension. This study investigates two-dimensional transport, with emphasis on the contribution of transverse dispersion to solute transport. Three problems were studied with a finite element code. The first problem involved one-dimensional flow parallel to the interface of two layers with differing pore- water velocity. The early arrival of the solute at the end of

the low-permeability layer and the increase-in solute spreading for both layers, as a result of transverse dispersion, were demonstrated. The two other problems concerned transport of a pollutant from a point source and a diffuse source, respectively, located at the soil surface. The magnitude of the transverse dispersion coefficient influenced the region to which the pollution extended as well as the intensity of the pollution. 59 NAL Call. No.: 292.8 W295 The effect of vertical soil heterogeneity on field scale solute flux. Destouni, G. Washington, D.C. : American Geophysical Union; 1992 May. Water resources research v. 28 (5): p. 1303-1309; 1992 May. Includes references. Language: English Descriptors: Solutes; Transport processes; Flow; Saturated hydraulic conductivity; Soil depth; Stochastic models Abstract: Vertical heterogeneity is incorporated in a stochastic transport model, in which the soil is viewed as consisting of an ensemble of essentially vertical, independent stream tubes. The saturated hydraulic conductivity in each stream tube is defined as the vertical average of the corresponding point random process. The statistics of the vertically averaged hydraulic conductivity and the resulting statistics of solute travel time are depth dependent. The evolution of the field scale breakthrough curve with depth is analyzed in terms of the first two moments of solute travel time to an arbitrary depth below the soil surface. The arrival time of the solute center of mass, quantified by the expected travel time, grows linearly with depth also for vertically heterogeneous soil. The temporal solute spreading around its center, quantified by the travel time variance, may exhibit a compression-expansion that is qualitatively analogous to the solute plume behavior in the studies of Butters and Jury (1989), Russo (1991), and Ellsworth and Jury (1991). The relative solute spreading, quantified by the travel time coefficient of variation, decreases with increasing depth. 60 NAL Call. No.: QH540.J6 Effects of climatic variations over 11 years on nitrate- nitrogen concentrations in the Raccoon River, Iowa. Lucey, K.J.; Goolsby, D.A. Madison, Wis. : American Society of Agronomy; 1992 Jan. Journal of environmental quality v. 22 (1): p. 38-46; 1992 Jan. Includes references. Language: English Descriptors: Iowa; Nitrate nitrogen; Drinking water; Seasonal variation; Precipitation; Stream flow; Water quality; Water pollution; Nitrogen fertilizers; Mathematical models

Abstract: Nitrate-nitrogen (NO3-N) concentrations at public water-supply intakes on the Des Moines and Raccoon Rivers in Iowa exceeded the maximum contaminant level (MCL) of 10 mg L-1 for public water supplies established by the USEPA for extended periods of time from March through early August 1990. The excessive NO3-N levels followed 2 yr of less than normal precipitation in 1988 and 1989. The largest daily NO3-N load (771 t) transported during the last 17 yr in the Raccoon River occurred in June 1990. The streamflow hydrograph for the Raccoon River for March 1990 prior to seasonal fertilizer application indicates that high NO3-N concentrations characterize the recession side of the hydrograph. High NO3-N concentrations in streamflow persisted as streamflow decreased to baseflow conditions. This implies that substantial quantities of NO3-N were being leached from the soil and transported by subsurface flow during early 1990. A multiple linear-regression model was developed to predict NO3-N concentrations in the Raccoon River from readily-obtainable streamflow and climatic data. The four-variable model explained about 70% of the variability in the concentration of NO3-N. The mean streamflow for the previous 7-d period accounted for about 50% of the total variability. 61 NAL Call. No.: 290.9 AM32T Effects of pesticide, soil, and rainfall characteristics on potential pesticide loss by percolation--a GLEAMS simulation. Truman, C.C.; Leonard, R.A. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Nov. Transactions of the ASAE v. 34 (6): p. 2461-2468; 1991 Nov. Includes references. Language: English Descriptors: Georgia; Pesticides; Percolation; Leaching; Losses from soil systems; Water pollution; Groundwater; Computer simulation; Zea mays Abstract: Potential pesticide loss in soil percolate is influenced by pesticide persistence and sorption by soil constituents (organic matter). Pesticide persistence, expressed as half-life (t1/2), changes with soil depth as microbial activity and soil properties change. Little is known, however, how these changes influence potential pesticide transport out of the root zone. Objectives of this study were to investigate relative differences in potential pesticide losses from the root zone by percolation due to 1) different soil surface and subsurface textures and pesticide t1/2, and 2) interactions between pesticide t1/2 arid timing of rainfall after pesticide application. The GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) model and a 50-year historical rainfall record at Tifton, Georgia, were used to simulate pesticide losses by percolation from three soils ranging in surface texture from sand to sandy clay loam. Hypothetical pesticides had surface t1/2 of 5, 15, 30, and 60 d and a range of subsurface t1/2

(2.5-360 d), and were applied to continuous corn (Zea maize, L.) at 2 kg ha-1 as surface spray at planting each year on 1 April. Simulated pesticide losses by percolation increased with increased surface and subsurface t1/2, and decreased with increased KOC (adsorption constant based on soil organic matter) values. Potential pesticide leaching was greatest for Lakeland sand and least for Greenville sandy clay loam. Rainfall timing affected simulated pesticide loss by percolation, especially for nonpersistent pesticides. For short pesticide t1/2 (0-5 d), excessive rainfall events within 1 t1/2 were largely responsible for simulated pesticide loss by percolation. Results indicate that changes in pesticide t1/2 in surface and subsurface horizons of different soils influence potential pesticide leaching from the root zone, and models (i.e., GLEAMS) can be used to provide comparative analysis of soil-pesticide-climate interactions. For example, dependi 62 NAL Call. No.: 292.8 W295 Effects of rainfall, vegetation, and microtopography on infiltration and runoff. Dunne, T.; Zhang, W.; Aubry, B.F. Washington, D.C. : American Geophysical Union; 1991 Sep. Water resources research v. 27 (9): p. 2271-2285; 1991 Sep. Includes references. Language: English Descriptors: Soil water; Infiltration; Runoff; Rain; Hill grasslands; Slope; Plant density; Hydraulic conductivity; Mathematical models Abstract: Apparent, or effective, infiltration rates on grassland hillslopes vary with rainfall intensity and flow depth because of the interaction between rainfall, runoff, and vegetated microtopography. The higher parts of the microtopography are occupied by greater densities of macropores and therefore have much greater hydraulic conductivities than the intervening microdepressions. On short hillslopes and plots the apparent infiltration rate is simply the spatial average of the saturated and unsaturated conductivities of this surface. The proportion of the surface which is saturated and the value to which the unsaturated conductivity is raised depends on the rainfall intensity. On longer hillslopes the downslope increase in flow depth in microtopographic depressions progressively inundates more permeable, vegetated mounds so that the hydraulic conductivity of a greater proportion of the surface is raised to its saturated value. For this reason the apparent infiltration rate increases downslope, even in the absence of spatial trends in any of the surface characteristics that affect infiltration. Apparent, or effective, infiltration rate depends on hillslope length. Consequently, steady state discharge does not increase linearly with distance downslope. These two fundamental relationships between infiltration, rainfall intensity, and runoff are analyzed on the basis of

sprinkling-infiltrometer measurements and a mathematical model. 63 NAL Call. No.: 292.8 W295 Effects of soil heterogeneity on pesticide leaching to groundwater. Zee, S.E.A.T.M. van der; Boesten, J.J.T.I. Washington, D.C. : American Geophysical Union; 1991 Dec. Water resources research v. 27 (12): p. 3051-3063; 1991 Dec. Includes references. Language: English Descriptors: Pesticides; Groundwater; Leaching; Hydrodynamic dispersion; Sorption; Transformation; Uptake; Physicochemical properties; Spatial variation; Stochastic models; Monte carlo method Abstract: Pesticide leaching was simulated numerically assuming Freundlich adsorption, first-order transformation and passive plant uptake, taking transient flow, hydrodynamic dispersion, and depth as well as temperature dependence of (bio)chemical parameters into account. The dependency of the leached fraction on sorption and transformation parameters appeared to be in good general agreement with the model developed by Jury et al. (1987). We incorporated spatial variability of (bio)chemical parameters into the piston flow model and showed how spatial variability may be accounted for without having to resort to demanding Monte Carlo techniques. Such spatial variability affects the leached fraction significantly. The data requirement of the simple stochastic model is small and the versatility relatively high. For parameter values often not of prime practical interest for pesticide screening this model fails. Considering transport by convection and dispersion in the semi-infinite domain, this spatial variability can be easily accounted for using parameter ranges for which our original analytical model for spatially variable piston transport failed. In this revised model, hydrodynamic dispersion, preferential flow, and spatial variability of transformation, sorption and soil thickness are dealt with in a similar fashion, while both correlation or the absence of correlation of parameters can be incorporated through an approximation of apparent residence time variance. 64 NAL Call. No.: QH540.J6 Effects of spatial accumulation of runoff on watershed response. Garbrecht, J. Madison, Wis. : American Society of Agronomy; 1991 Jan. Journal of environmental quality v. 20 (1): p. 31-35; 1991 Jan. Literature review. Includes references. Language: English Descriptors: Watersheds; Drainage; Hydrology; Rain; Runoff; Simulation models

Abstract: The drainage network accumulates upstream subwatershed runoff into a single downstream response, with runoff accumulating at network junctions. The effects of this accumulation on the magnitude and spatial variability of the downstream response are reviewed for simplified boundary conditions. Runoff parameters are runoff depth and corresponding unit area peak runoff rate. At the subwatershed level these parameters are referred to as d and q, respectively, and they vary from one subwatershed to another. At a downstream location, after accumulation by the drainage network, corresponding parameters are referred to as D and Q. Equations expressing the effects of runoff accumulation are formulated and discussed for uniform rainfall conditions. The review shows that the effects of runoff accumulation gain in importance as the number of upstream subwatersheds and the size of the watershed increase in the downstream direction. The accumulation process cancels extreme values of d and q to yield a representative D and Q value for the entire upstream drainage area. The impact of individual d and q values on the downstream D and Q values in the channel diminishes as the number of upstream subwatersheds increases. This results in a decrease in the spatial variability of D and Q in the downstream direction. The review suggests that the role of spatial variability of upstream d and q in the determination of downstream D and Q diminishes as watershed size increases. However, nonuniform rainfall distributions and storm movement may overshadow the effects of runoff accumulation when watershed size increases beyond the size of the storm. 65 NAL Call. No.: 325.28 P56 Effects of suspended particle size and concentration on reflectance measurements. Bhargava, D.S.; Mariam, D.W. Bethesda, Md. : American Society of Photogrammetry and Remote Sensing; 1991 May. Photogrammetric engineering and remote sensing v. 57 (5): p. 519-529; 1991 May. Includes references. Language: English Descriptors: Soil types; Suspensions; Particle size; Sediment; Concentration; Reflectance; Responses; Prediction; Models; Turbidity; Water quality; Equations; Remote sensing 66 NAL Call. No.: TD403.G7 Effects of waste-water irrigation on aqueous geochemistry near Paris, Texas. Tedaldi, D.J.; Loehr, R.C. Dublin, Ohio : Ground Water Pub. Co; 1992 Sep. Ground water v. 30 (5): p. 709-719; 1992 Sep. Includes references. Language: English Descriptors: Texas; Waste water; Irrigation; Long term experiments; Groundwater; Water quality; Soil chemistry;

Geochemistry; Prediction; Thermodynamics; Equilibrium; Models; Aquifers; Saline water; Recharge; Infiltration; Hydraulic conductivity 67 NAL Call. No.: TD420.A1E5 Elution of aged and freshly added herbicides from a soil. Pignatello, J.J.; Ferrandino, F.J.; Huang, L.Q. Washington, D.C. : American Chemical Society; 1993 Aug. Environmental science & technology v. 27 (8): p. 1563-1571; 1993 Aug. Includes references. Language: English Descriptors: Connecticut; Soil pollution; Herbicide residues; Atrazine; Metolachlor; Leaching; Profiles; Models 68 NAL Call. No.: S539.5.J68 Environmental and economic impacts of pesticide and irrigation practices: EPIC-PST simulation. Sabbagh, G.J.; Norris, P.E.; Geleta, S.; Bernado, D.J.; Elliott, R.L.; Mapp, H.P.; Stone, J.F. Madison, Wis. : American Society of Agronomy; 1992 Jul. Journal of production agriculture v. 5 (3): p. 312-317; 1992 Jul. Includes references. Language: English Descriptors: Oklahoma; Groundwater pollution; Crop management; Environmental impact; Economic impact; Pest control; Irrigation; Computer techniques; Simulation models; Pesticides; Movement in soil; Runoff 69 NAL Call. No.: 292.8 W295 Estimating changes in recreational fishing participation from national water quality policies. Ribaudo, M.O.; Piper, S.L. Washington, D.C. : American Geophysical Union; 1991 Jul. Water resources research v. 27 (7): p. 1757-1763; 1991 Jul. Includes references. Language: English Descriptors: Water quality; Water policy; Water pollution; Angling; Participation; Estimation; Models Abstract: The complete evaluation of the offsite effects of national policies or programs that affect levels of agricultural nonpoint source pollution requires linking extensive water quality changes to changes in recreational activity. A sequential decision model is specified to describe an individual's decisions about fishing. A participation model for recreational fishing that includes a water quality index reflecting regional water quality is developed and estimated as a logit model with national level data. A visitation model

for those who decide to fish that also includes the water quality index is estimated using ordinary least squares. The water quality index is found to be significant in the participation model but not in the visitation model. Together, the two models provide a means of estimating how changes in water quality might influence the number of recreation days devoted to fishing. The model is used to estimate changes in fishing participation for the Conservation Reserve Program. 70 NAL Call. No.: TC401.W27 Estimating low flow characteristics in ungauged catchments. Nathan, R.J.; McMahon, T.A. Dordrecht : Kluwer Academic Publishers; 1992. Water resources management v. 6 (2): p. 85-100; 1992. Includes references. Language: English Descriptors: New South Wales; Victoria; Watersheds; Rural areas; Flow; Characteristics; Water yield; Rain; Runoff; Models; Multivariate analysis; Climatic factors; Hydrological data; Equations 71 NAL Call. No.: 292.8 J82 Estimating transport parameters at the grid scale: on the value of a single measurement. Beven, K.J. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 Mar01. Journal of hydrology v. 143 (1/2): p. 109-123; 1993 Mar01. Special Issue: Modelling Flow and Transport in the Unsaturated Zone: Scale Problems and Spatial Variability. Includes references. Language: English Descriptors: Solutes; Transport processes; Soil water; Flow; Spatial variation; Hydrodynamic dispersion; Prediction; Estimation; Probabilistic models Abstract: Distributed models of solute transport at the field and catchment scales require the specification of effective parameters at the model grid scale. The grid scale will generally be much larger than the scale at which it is possible to make measurements to derive parameter values but may be of the same order as the scale of variability of such 'point' values. In addition, measurements are usually expensive and time consuming to make and where, for example, 'undisturbed' soil cores are used, may be destructive. This paper describes a conditional probability based approach for estimating grid scale effective parameter values in the light of expected spatial heterogeneity, given only one or a small number of available measurements. Initial results show, somewhat surprisingly, that despite the integrative nature of the spatial averaging involved in moving to the grid scale, the variance of the effective grid element values does not

decrease. There is a small shift in the location of the distribution, as a result of the macrodispersive effect of the grid scale variability. 72 NAL Call. No.: GB746.W33 Estimation of possible anthropogenic changes in the runoff and removal of biogenic elements from small watersheds of the forest zone on the basis of a mathematical model. Kondrat'ev, S.A. New York, N.Y. : Consultants Bureau; 1991 Mar. Water resources v. 17 (3): p. 240-248; 1991 Mar. Tranlated from: Vodnye Resursy, V. 17, No. 3, May/June 1990, p. 24-32. (GB746.V55). Includes references. Language: English; Russian Descriptors: U.S.S.R.in europe; Rsfsr; Runoff water; Sediment; Formation; Water pollution; Nutrients; Removal; Phosphorus; Nitrogen; Agricultural production; Effects; Watersheds; Forests; Hydrology; Mathematical models 73 NAL Call. No.: 292.8 J82 Evaluating the green and ampt infiltration parameter values for tilled and crusted soils. Mohamoud, Y.M. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Feb. Journal of hydrology v. 123 (1/2): p. 25-38; 1991 Feb. Includes references. Language: English Descriptors: Illinois; Agricultural soils; Rain; Infiltration; Soil water content; Runoff; Surface layers; Tillage; Crop residues; Crusts; Permeability; Capillary rise; Wetting front; Hydraulic conductivity; Mathematical models; Green and ampt equation Abstract: Methods for determining Green-Ampt infiltration parameter values for tilled and crusted soils are not well established. A two-stage method is developed to determine the Green and Ampt parameter values for soils under different management practices. The first stage is aimed at calculating rainfall infiltration from rainfall and runoff data of small field plots which had different soil surface conditions (e.g. tillage, residue cover and crusting). To determine accurate rainfall infiltration rates from field plots, we employed a water balance model which accounted for depression storage, detention storage as well as surface routing of runoff. The second stage is aimed at evaluating the values of the Green and Ampt infiltration equation parameters by the linear least squares parameter estimation technique. The Green and Ampt parameter values determined were the effective capillary suction at the wetting front and the effective hydraulic conductivity. The results of this study indicated that this procedure is sufficiently sensitive to reflect the effects of

tillage, residue cover and crusting on infiltration data. Raindrop impact reduced infiltration rates by crusting the soil surface. However, most of the management systems that left about 30% of residue cover protected the soil from raindrop impact as evidenced by the higher effective hydraulic conductivity. It is concluded that the model developed by Green and Ampt in 1911 satisfactorily fitted the infiltration data obtained from protected and crusted soil profiles. Also, residue cover and crusting greatly influenced the Green and Ampt infiltration parameter values. 74 NAL Call. No.: TP995.A1I5 Evaluating transport of organic chemicals in soil resulting from underground fuel tank leaks. Lee, D.Y.; Chang, A.C. Chelsen, Mich. : Lewis Publishers; 1992. Proceedings of the Industrial Waste Conference (46): p. 131-140; 1992. Meeting held May 14-16, 1991, West Lafayette, Indiana. Includes references. Language: English Descriptors: Polluted soils; Soil pollution; Organic compounds; Petroleum; Petroleum hydrocarbons; Transport processes; Fuel tanks; Leakage; Underground storage; Simulation models; Equations; Mathematics; Groundwater pollution; Soil water movement; Movement in soil 75 NAL Call. No.: GB701.W375 no.91-4142 Evaluation of a ground-water flow and transport model of the upper Coachella Valley, California.. Evaluation of a ground water flow and transport model of the upper Coachella Valley, California Reichard, Eric George; Meadows, J. Kevin Geological Survey (U.S.),California Regional Water Quality Control Board--Colorado River Basin Region Sacramento, Calif. : U.S. Geological Survey ; Denver, CO : Books and Open-File Reports Section [distributor],; 1992. vi, 101 p. : ill., maps ; 28 cm. (Water-resources investigations report ; 91-4142). Includes bibliographical references (p. 42). Language: English Descriptors: Groundwater flow; Water, Underground 76 NAL Call. No.: TD426.J68 Evaluation of a pesticide mobility index: impact of recharge variation and soil profile heterogeneity. Kleveno, J.J.; Loague, K.; Green, R.E. Amsterdam : Elsevier; 1992 Oct. Journal of contaminant hydrology v. 11 (1/2): p. 83-99; 1992 Oct. Includes references.

Language: English Descriptors: Hawaii; Soil pollution; Pesticides; Profiles; Movement in soil; Attenuation; Leaching; Assessment; Simulation models; Errors; Movement to roots; Rain 77 NAL Call. No.: 290.9 AM32T Evaluation of fluvial sediment transport equations for overland flow. Guy, B.T.; Dickinson, W.T.; Rudra, R.P. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Mar. Transactions of the ASAE v. 35 (2): p. 545-555. ill; 1992 Mar. Includes references. Language: English Descriptors: Geological sedimentation; Overland flow; Rain; Runoff; Splash erosion; Simulation models Abstract: Sediment transport capacity was measured under a range of conditions in two types of overland flow: shallow uniform flow in the absence of rainfall, and shallow flow affected by rainfall impact. The abilities of six fluvial sediment transport equations to represent each dataset are evaluated. For both flow types, common aspects of equation performance include poor representation of sediment transport thresholds, underprediction of transport rates, and significant scatter about measured values. These problems, particularly the equations' inability to predict transport threshold, are more evident with the rain-impacted now data. Only the Schoklitsch equation is suitable for uniform overland flow without rain-impact, and none am suitable for rain- impacted overland flow. 78 NAL Call. No.: 290.9 AM32T Evaluation of PRZM and LEACHMP on intact soil columns. Smith, W.N.; Prasher, S.O.; Barrington, S.F. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Nov. Transactions of the ASAE v. 34 (6): p. 2413-2420; 1991 Nov. Includes references. Language: English Descriptors: Atrazine; Computer simulation; Leaching; Soil properties; Water pollution Abstract: Limiting factors towards the utilization of pesticide transport models are lack of both detailed data and cognizant personnel available to test and validate model predictions. In this study, computer simulations were carried out to test the performance of PRZM (a management model) and LEACHMP (a research model) on leaching characteristics of atrazine in long intact soil columns. Also, in an attempt to evaluate model uncertainty, a sensitivity analysis of several parameters for each model was considered. LEACHMP was found to be superior in predicting hydrological characteristics in the

soil columns as compared to PRZM which required calibration. Both models underestimated levels of atrazine near the soil surface and in the leachate (115 cm depth) and over-estimated them throughout most of the range in-between. Inaccurate predictions for the two models are attributed to simplistic linear adsorption equations and lack of a macropore flow subroutine. In increasing order, PRZM was most sensitive to rate of application, distribution coefficient, bulk density and field capacity, whereas LEACHMP was sensitive to rate of application, organic carbon distribution coefficient, air entry value, and bulk density. 79 NAL Call. No.: 292.8 J82 Evaluation of the accuracy and precision of annual phosphorus load estimates from two agricultural basins in Finland. Rekolainen, S.; Posch, M.; Kamari, J.; Ekholm, P. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Nov. Journal of hydrology v. 128 (1/4): p. 237-255; 1991 Nov. Includes references. Language: English Descriptors: Finland; Agricultural land; Drainage; Runoff; Pollution; Phosphorus; Transport processes; Flow; Estimates; Sampling; Frequency; Monitoring; Mathematical models; Comparisons Abstract: The accuracy and precision of phosphorus load estimates from two agricultural drainage basins in western Finland were evaluated, based on continuous flow measurements and frequent flow-proportional sampling of total phosphorus concentration during a 2 year period. The objective was to compare different load calculation methods and to evaluate alternative sampling strategies. An hourly data set of concentrations was constructed by linear interpolation, and these data were used in Monte Carlo runs for producing replicate data sets for calculating the accuracy and precision of load estimates. All estimates were compared with reference values computed from the complete hourly data sets. The load calculation methods based on summing the products of regularly sampled flows and concentrations produced the best precision, whereas the best accuracy was achieved using methods based on multiplying annual flow by flow-weighted annual mean concentration. When comparing different sampling strategies, concentrating sampling in high runoff periods (spring and autumn) was found to give better accuracy and precision than strategies based on regular interval sampling throughout the year. However, the best result was obtained by taking samples flow-proportionally within the highest peak flows plus additional regular interval (e.g. biweekly) samples outside these flow peaks. Using this strategy, which calls for automatic sampling equipment, accuracies better than 5% and precisions better than 10% can be achieved with only 30-50 samples per year.

80 NAL Call. No.: 290.9 AM32T Evaluation of the hydrologic component of the ADAPT water table management model. Chung, S.O.; Ward, A.D.; Schalk, C.W. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Mar. Transactions of the ASAE v. 35 (2): p. 571-579; 1992 Mar. Includes references. Language: English Descriptors: Tile drainage; Water management; Water table; Evapotranspiration; Hydrology; Macropore flow; Runoff; Seepage; Simulation models Abstract: A subsurface, water table management model ADAPT (Agricultural Drainage and Pesticide Transport) has been developed by combining drainage and subirrigation algorithms from DRAINMOD with the GLEAMS model. In addition, the model incorporates improved snow melt and runoff algorithms, macropore flow due to cracking, and deep seepage. Theory for the hydrologic components of the model is presented together with an evaluation of the model using data from a long-term field experiment at Castalia in North Central Ohio. Predicted surface runoff, subsurface drainage, and combined surface and subsurface drainage are compared with the field observations. In general, the model predictions are within the range of the variations of the observed replications. Sensitivity analysis shows that surface runoff estimates are sensitive to changes in curve number, while subsurface drainage flows are sensitive to deep seepage estimates. Model input requirements are not excessive and the model gives reasonable estimates of the hydrologic component of water table management systems. ADAPT can be used in designing water table management systems and does not require extensive calibration. The pesticide component of ADAPT is currently being evaluated and development of a nutrient component has been initiated. 81 NAL Call. No.: 4 AM34P Evaluation of the nitrogen submodel of CERES-maize following legume green manure incorporation. Bowen, W.T.; Jones, J.W.; Carsky, R.J.; Quintana, J.O. Madison, Wis. : American Society of Agronomy; 1993 Jan. Agronomy journal v. 85 (1): p. 153-159; 1993 Jan. Includes references. Language: English Descriptors: Simulation models; Prediction; Nutrient uptake; Nitrogen; Green manures; Nutrient availability; Mineralization; Leaching; Nitrate; Losses from soil; Nitrogen balance Abstract: Crop simulation models that accurately predict the availability of N from decomposing plant residues would provide a powerful tool for evaluating legume green manures as potential N sources for nonlegume crops. Using measured data

from a series of field experiments conducted on an Oxisol in central Brazil, we conducted this study to test the N submodel of CERES-Maize for its ability to simulate N mineralization, nitrate leaching, and N uptake by maize (Zea Mays L.) following the incorporation of 10 different legume green manures. Legume or weed residue N at the time of incorporation varied from 25 to 300 kg ha-1 with C/N ratios varying from 13 to 37. Comparison of predicted and measured accumulation of inorganic N in uncropped soil showed that the model usually provided a realistic simulation of legume N release, although N release was overpredicted for some legumes. For all legumes, both simulated and measured data showed that about 60% of the organic N applied was recovered as inorganic N within 120 to 150 d after incorporation. To realistically simulate N availability when rainfall was excessive, we modified the model to account for delayed leaching due to nitrate retention in the subsoil. Nitrogen uptake by maize was generally overpredicted at high levels of available N. The N submodel was shown to realistically simulate legume N release, but further work is needed to determine the importance of subsoil nitrate retention in other soils and how best such retention might be described in the model. 82 NAL Call. No.: 290.9 AM32T An evaluation of unit stream power theory for estimating soil detachment and sediment discharge from tilled soils. McIsaac, G.F.; Mitchell, J.K.; Hummel, J.W.; Elliot, W.J. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Mar. Transactions of the ASAE v. 35 (2): p. 535-544; 1992 Mar. Includes references. Language: English Descriptors: Illinois; Water erosion; Aggregates; Runoff; Sediment yield; Simulation models; Soil properties; Streams; Tillage Abstract: Unit Stream Power (USP) and the associated Yang (1973) sediment transport equations were compared to soil detachment rates and sediment concentrations in runoff from eroding soils. Although USP was significantly correlated with rill detachment rates, potential energy dissipation rate per unit rill area was a better predictor of soil detachment rates. The Yang (1973) equations estimated sediment concentrations within a factor of 10 of the observed concentrations, if the median soil aggregate diameter was within the range of diameters used by Yang to estimate the equation parameters. When median aggregate sizes were less than 0.15 mm, the lower limit of Yang's (1973) calibration range, the equations tended to produce unrealistically large estimates of sediment concentration. 83 NAL Call. No.: ViBlbVLD5655.V856 1992.J663 Evaluation of water distribution system monitoring using stochastic dynamic modeling.

Jones, Philip Edward James, 1992; 1992. xiv, 215 leaves : ill. ; 28 cm. Vita. Abstract. Bibliography: leaves 181-191. Language: English Descriptors: Water quality management; Water 84 NAL Call. No.: 56.8 SO3 Exit condition for miscible displacement experiments. Parlange, J.Y.; Starr, J.L.; Van Genuchten, M.Th; Barry, D.A.; Parker, J.C. Baltimore, Md. : Williams & Wilkins; 1992 Mar. Soil science v. 153 (3): p. 165-171; 1992 Mar. Includes references. Language: English Descriptors: Transport processes; Solutes; Soil solution; Soil analysis; Mathematical models; Determination; Convection; Dispersion; Length; Movement in soil; Kinetics 85 NAL Call. No.: 56.8 SO3 Experimental and simulated B transport in soil using a multireaction model. Mansell, R.S.; Bloom, S.A.; Burgoa, B.; Nkedi-Kizza, P.; Chen, J.S. Baltimore, Md. : Williams & Wilkins; 1992 Mar. Soil science v. 153 (3): p. 185-194; 1992 Mar. Includes references. Language: English Descriptors: Florida; Spodosols; Acid soils; Sandy soils; B horizons; Subsurface layers; Phosphorus; Movement in soil; Transport processes; Soil water movement; Determination; Laboratory methods; Simulation models; Mathematical models; Sorption; Kinetics; Sorption isotherms; Comparisons; Fixation; Soil organic matter; Aluminum oxide; Iron oxides 86 NAL Call. No.: HC79.E5E5 Exploring the effects of multiple management objectives and exotic species on Great Lakes food webs and contaminant dynamics. Fontaine, T.D.; Stewart, D.J. New York, N.Y. : Springer-Verlag; 1992 Mar. Environmental management v. 16 (2): p. 225-229; 1992 Mar. Includes references. Language: English Descriptors: Fishery management; Lakes; Water quality; Food chains; Objectives; Simulation models

87 NAL Call. No.: S539.5.J68 Farm-level economic and environmental impacts of eastern Corn Belt cropping systems. Foltz, J.C.; Lee, J.G.; Martin, M.A. Madison, WI : American Society of Agronomy, c1987-; 1993 Apr. Journal of production agriculture v. 6 (2): p. 290-296; 1993 Apr. Includes references. Language: English Descriptors: Corn belt states of U.S.A.; Cabt; Zea mays; Medicago sativa; Glycine max; Microeconomic analysis; Economic impact; Alternative farming; Environmental impact; Rotations; Continuous cropping; Simulation models; Computer simulation; Erosion; Runoff; Pesticides; Water pollution 88 NAL Call. No.: TD201.A4 A fast and accurate method for solving subsurface contaminant transport problems with a single uncertain parameter. Ahlfeld, D.P.; Pinder, G.F. Essex : Elsevier Science Publishers Ltd; 1992. Advances in water resources v. 15 (2): p. 143-150; 1992. Includes references. Language: English Descriptors: Groundwater pollution; Contaminants; Transport; Equations; Random sampling; Stochastic models; Groundwater flow; Hydraulic conductivity 89 NAL Call. No.: QH545.A1E58 Fate, dissipation and environmental effects of pesticides in southern forests: a review of a decade of research progress. Neary, D.G.; Bush, P.B.; Michael, J.L. Tarrytown, N.Y. : Pergamon Press; 1993 Mar. Environmental toxicology and chemistry v. 12 (3): p. 411-428; 1993 Mar. Paper presented at the "Symposium on Pesticides in Forest Management, 11th Annual Meeting of the Society of Environmental Toxicology and Chemistry," November 11-15, 1990, Arlington, Virginia. Literature review. Includes references. Language: English Descriptors: Southern states of U.S.A.; Pesticides; Forestry; Ecosystems; Watersheds; Environmental impact; Water quality; Air quality; Groundwater pollution; Silviculture; Species diversity; Simulation models; Nontarget effects; Literature reviews 90 NAL Call. No.: QH540.N3 Fate of non-aqueous phase liquids: modeling of surfactant effects. Harwell, J.H.; Sabatini, D.A.; Soerens, T.S. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p.

309-328; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Pollutants; Organic compounds; Transport processes; Groundwater flow; Soil water movement; Equations; Mathematics 91 NAL Call. No.: TP963.A1F4 Fertilization under drip irrigation. Bar-Yosef, B. New York, N.Y. : Marcel Dekker; 1991. Fertilizer science and technology series v. 7: p. 285-329; 1991. In the series analytic: Fluid fertilizer science and technology / edited by D.A. Palgrave. Includes references. Language: English Descriptors: Fertigation; Liquid fertilizers; Fluids; Trickle irrigation; Fertilizer requirement determination; Irrigation water; Ph; Salinity; Plant nutrition; Nutrient requirements; Nutrient uptake; Temporal variation; Nitrogen; Movement in soil; Transport processes; Spatial distribution; Root systems; Soil water content; Soil solution; Mathematical models; Monitoring; Fertilizer technology; Management; Crop production 92 NAL Call. No.: QD1.A45 Field and model estimates of pesticide runoff from turfgrass. Rosenthal, W.D.; Hipp, B.W. Washington, D.C. : The Society; 1993. ACS Symposium series - American Chemical Society (522): p. 208-213; 1993. In the series analytic: Pesticides in urban environments: Fate and significance / edited by K.D. Racke and A.R. Leslie. Paper presented at the 203rd National Meeting of the American Chemical Society, April 5-10, 1992, San Francisco, California. Includes references. Language: English Descriptors: Chlorpyrifos; Carbaryl; Diazinon; 2,4-d; Dicamba; Atrazine; Fertilizers; Herbicide residues; Insecticide residues; Runoff water; Mathematical models; Simulation models; Cynodon dactylon; Buchloe dactyloides Abstract: Environmental awareness of surface runoff water quality is increasing. A study was conducted to analyze the impact of different turfgrass fertilizer and pesticide management systems on runoff water quality. A hydrologic and water quality model, Erosion Productivity Impact Calculator (EPIC), was used to estimate pesticide and nutrient concentrations in runoff from turfgrass on a Houston Black

Clay. Nutrient and pesticide concentrations in the surface runoff increased significantly for highly maintained turfgrass systems. A larger fraction of the amount applied was observed in runoff for the moderate application rate treatments. Simulated results are being validated from measured runoff of turfgrass plots at Dallas, TX. 93 NAL Call. No.: S478.S68T43 no.31 Field measurement and modelling of runoff and erosion response of small agricultural catchments in the mid north of South Australia. Punthakey, J.F. Adelaide, South Australia : Dept. of Agriculture,; 1992. v, 137 p. : ill. ; 30 cm. (Technical paper (South Australia. Dept. of Agriculture) ; no. 31.). May 1992. AGDEX 572. Includes bibliographical references (p. 134-137) and index. Language: English 94 NAL Call. No.: 56.9 SO3 Field study of bromacil transport under continuous-flood irrigation. Jaynes, D.B. Madison, Wis. : The Society; 1991 May. Soil Science Society of America journal v. 55 (3): p. 658-664; 1991 May. Includes references. Language: English Descriptors: Bromacil; Flood irrigation; Herbicide residues; Leaching; Movement in soil; Transport processes; Agricultural soils; Mathematical models Abstract: The transport processes of sorbing chemicals in field soils are poorly understood. This study characterized the leaching behavior of the weakly sorbing herbicide bromacil (5-bromo-3-sec-butyl-6-methyluracil) in comparison to Br- during continuous-flood irrigation of a small field plot. Twenty-four solution samplers were used to periodically collect in situ samples from seven depths within four 1.83 by 1.83 m subplots. Estimates of the pore water velocity (vs) and dispersion coefficient (D) were made by fitting an analytical solution of the convection-dispersion (CD) equation to the Br- data. Estimates of retardation (R) were made by fitting the CD equation to the bromacil data using the vs and D estimates from the Br- data and letting R be a fitting parameter. Estimates of R were also made from the results of batch equilibration studies using soil from seven depths. Best-fit vs and D values exhibited considerable variability from sampler to sampler (CV = 1.25 and 1.30, respectively) and showed no significant trends with depth. Retardation values estimated from the CD equation averaged 1.88, but varied from 1.21 to 3.35 and also showed no significant trend with depth. In contrast, batch equilibration studies showed the absorption properties of the surface 0.6 m of soil to be significantly different than the 0.6- to 3-m depth, with R values decreasing from 1.62 for the surface 0.6 m to 1.31 at 3 m. Although the

two methods gave the same estimate of R in the surface soil neither the lower R values at deeper depths nor the tendency to decrease with depth as predicted from the batch studies was apparent in the transport data. Using D as an additional fitting parameter to the bromacil data resulted in an average increase of 1.96 for this parameter, indicating more dispersion for the sorbing solute. Increased dispersion and increased tailing of the sorbed solute may be attributed to spatially variable adsorption and to a negative correlation between vs and R (r = -0.524) 95 NAL Call. No.: 290.9 AM32T Field testing and comparison of the PRZM and GLEAMS models. Smith, M.C.; Bottcher, A.B.; Campbell, K.L.; Thomas, D.L. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 May. Transactions of the ASAE v. 34 (3): p. 838-847; 1991 May. Includes references. Language: English Descriptors: Georgia; Alachlor; Atrazine; Bromides; Field tests; Leaching; Groundwater; Pesticides; Precipitation; Runoff; Simulation models; Soil properties; Soil water Abstract: The root/vadose zone transport models PRZM and GLEAMS were tested against an experimental data set. Parameters were not optimized or calibrated to produce the best fit. In all cases the measured and predicted peak concentrations agreed within an order of magnitude, and in most cases agreed within a factor of 2 to 3. This level of agreement between the models and the measured data is within the criteria for model acceptance suggested by the EPA. The small differences noted in simulated transport between the models are thought to be a result of differences in computational layering and chemical transport calculation methods. 96 NAL Call. No.: TD426.J68 Fluid flow and solute transport processes in unsaturated heterogeneous soils: Preliminary numerical experiments. Liu, C.C.K.; Loague, K.; Feng, J.S. Amsterdam : Elsevier; 1991 Feb. Journal of contaminant hydrology v. 7 (3): p. 261-283; 1991 Feb. Includes references. Language: English Descriptors: Movement in soil; Pollutants; Unsaturated flow; Mathematical models; Finite element analysis; Prediction; Aquifers 97 NAL Call. No.: S539.5.J68 Functional form selection for regional crop response to salinity, water application, and climate.

Lee, D.J. Madison, Wis. : American Society of Agronomy; 1992 Oct. Journal of production agriculture v. 5 (4): p. 445-454; 1992 Oct. Includes references. Language: English Descriptors: Zea mays; Sorghum bicolor; Triticum aestivum; Triticum turgidum; Irrigation; Application rates; Saline water; Water quality; Mathematical models; Crop yield; Soil salinity; Climatic factors 98 NAL Call. No.: QH540.J6 A functional model of solute transport that accounts for bypass. Corwin, D.L.; Waggoner, B.L.; Rhoades, J.D. Madison, Wis. : American Society of Agronomy; 1991 Jul. Journal of environmental quality v. 20 (3): p. 647-658; 1991 Jul. Includes references. Language: English Descriptors: Groundwater; Water quality; Transport processes; Solutes; Water management; Mathematical models Abstract: Public awareness of groundwater contamination has created renewed interest in solute transport models that can be practically applied as groundwater quality management tools. Because of their simplicity with regard to input requirements, functional models of solute transport are excellent groundwater quality management tools. A functional model of one-dimensional solute transport that accounts for hydraulic bypass is presented. The transport model TETrans, simulates the vertical movement of nonvolatile solutes (i.e., trace elements and nonvolatile organic chemicals) through the vadose zone. Plant water uptake is taken into account assuming no solute uptake by the plant. TETrans requires minimal input data for its operation. Since TETrans uses a mass-balance approach to solute transport, it offers the speed of an analytical solution and the versatility of a numerical approach without the need for input parameters, which are difficult to measure. TETrans is able to account for bypass with a single term, the mobility coefficient. The mobility coefficient, gamma, represents the fraction of the soil liquid phase, which is subject to piston-type displacement; therefore, 1 - gamma represents the fraction of the liquid phase that is bypassed. The mobility coefficient is a temporally and spatially variable parameter (within a range of 0 to l) which is calculated from the deviation of the measured chloride concentration from the predicted concentration assuming piston displacement and assuming complete mixing of the resident soil solution and incoming water for a given irrigation and volume of soil. A constant mobility coefficient for a given depth or entire profile can be determined by averaging temporally varying mobility coefficients or averaging spatially and temporally varying mobility coefficients, respectively. In essence, the mobility

coefficient simplistically accounts for three physical transport phenomena in a single term. On a microscopic level there is flow thr 99 NAL Call. No.: 290.9 AM32T Generic anaerobic digestion model for the simulation of various reactor types and substrates. Thomas, M.V.; Nordstedt, R.A. St. Joseph, Mich. : American Society of Agricultural Engineers; 1993 Mar. Transactions of the ASAE v. 36 (2): p. 537-544; 1993 Mar. Literature review. Includes references. Language: English Descriptors: Florida; Agricultural wastes; Animal wastes; Hyacinths; Manures; Straw; Waste disposal; Anaerobic digestion; Literature reviews; Mathematical models; Methane production Abstract: A mathematical model was developed to represent a wide variety of anaerobic reactor types and substrates. The model is a generic, anaerobic digestion process model, using lumped substrate parameters, and was developed for use as type-specific reactor model operating within the sphere of a larger system model. Three types of anaerobic reactors were simulated: fixed-bed reactors, conventional stirred tank reactors, and continuously expanding reactors. The generic anaerobic digestion model provided a tool for testing various values of conversion efficiency and kinetic parameters for a wide range of substrate types and reactor designs. 100 NAL Call. No.: 292.8 W295 A geochemical transport model for redox-controlled movement of mineral fronts in groundwater flow systems: a case of nitrate removal by oxidation of pyrite. Engesgaard, P.; Kipp, K.L. Washington, D.C. : American Geophysical Union; 1992 Oct. Water resources research v. 28 (10): p. 2829-2843; 1992 Oct. Includes references. Language: English Descriptors: Denmark; Groundwater flow; Transport processes; Denitrification; Pyrites; Oxidation; Nitrate; Reduction; Redox reactions; Geochemistry; Spatial distribution; Algorithms; Mathematical models; Simulation Abstract: A one-dimensional prototype geochemical transport model was developed in order to handle simultaneous precipitation-dissolution and oxidation-reduction reactions governed by chemical equilibria. Total aqueous component concentrations are the primary dependent variables, and a sequential iterative approach is used for the calculation. The model was verified by analytical and numerical comparisons and is able to simulate sharp mineral fronts. At a site in Denmark, denitrification has been observed by oxidation of

pyrite. Simulation of nitrate movement at this site showed a redox front movement rate of 0.58 m yr-1, which agreed with calculations of others. It appears that the sequential iterative approach is the most practical for extension to multidimensional simulation and for handling large numbers of components and reactions. However, slow convergence may limit the size of redox systems that can be handled. 101 NAL Call. No.: 56.9 SO32 Geographic information system for differentiating unused wells. Tan, Y.R.; Shih, S.F. S.l. : The Society; 1991. Proceedings - Soil and Crop Science Society of Florida v. 50: p. 110-116; 1991. Paper presented at the "Symposium on Reality of Sustainable Agriculture in Florida, September 26-28, 1990, Daytona Beach, FLorida. Includes references. Language: English Descriptors: Florida; Groundwater; Wells; Water management; Geographical distribution 102 NAL Call. No.: QE1.E5 Geostatistical modeling of salinity as a basis for irrigation management and crop selection--a case study in central Tunisia. Soderstrom, M. New York, N.Y. : Springer; 1992 Sep. Environmental geology and water sciences v. 20 (2): p. 85-92; 1992 Sep. Includes references. Language: English Descriptors: Tunisia; Groundwater; Saline water; Irrigation water; Spatial distribution; Soil salinity; Irrigated soils; Wells; Water; Soil; Sampling; Maps; Leaching; Models; Irrigation scheduling; Crop yield; Yield losses; Crops; Selection 103 NAL Call. No.: QH541.5.D4J6 A GIS approach to desertification assessment and mapping. Grunblatt, J.; Ottichilo, W.K.; Sinange, R.K. London : Academic Press; 1992 Jul. Journal of arid environments v. 23 (1): p. 81-102; 1992 Jul. Includes references. Language: English Descriptors: Kenya; Desertification; Remote sensing; Satellite imagery; Models; Geography 104 NAL Call. No.: S671.A66 GIS-assisted input data set development for the Finite Element

Storm Hydrograph Model (FESHM). Wolfe, M.L. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Mar. Applied engineering in agriculture v. 8 (2): p. 221-227; 1992 Mar. Includes references. Language: English Descriptors: Hydrology; Simulation models; Automation; Computer techniques Abstract: A study was conducted to develop an automated proceedings to assist in the development of input data sets for the FESHM hydrologic model using the GRASS geographic information system. Shell scripts (executable sequences of commands in the UNIX operating system) were developed to overlay soils and land use maps to generate hydrologic response unit (HRU) maps and to compute the fractional areas of HRUs in overland flow elements. The automated procedures decreased the input data set development time significantly, by approximately 250% (from five to two hours) for a 122 ha (303 ac) watershed. The time savings on larger, more variable watersheds would be even greater. The input data set development procedure provides an efficient manner for considering alternative land use and management scenarios. 105 NAL Call. No.: 292.9 AM34 Ground water quality implications of soil conservation measures: an economic perspective. Setia, P.; Piper, S. Bethesda, Md. : American Water Resources Association; 1991 Mar. Water resources bulletin v. 27 (2): p. 201-208; 1991 Mar. Includes references. Language: English Descriptors: Corn belt of U.S.A.; Soil conservation; Groundwater; Water quality; Pesticides; Runoff; Leaching; Agricultural economics; Usda; Federal programs Abstract: An evaluation of the intermedia movement of pesticides applied under various land management systems already in place, or to be implemented, under the Conservation Reserve and Conservation Compliance programs is presented. The simulation modeling approach followed in this analysis consists of a mathematical programming model and leaching/surface runoff, Pesticide Root Zone Model (PRZM) models. Special care was taken to ensure that the physical model was sensitive to the chemical characteristics of individual pesticides and the important physical changes brought about by different agricultural practices. Results show that, although these programs as now planned, increase farm income and achieve soil conservation goals, they may adversely affect ground water quality. Also, depending on soil and location characteristics, there are tradeoffs between surface and ground water quality implications. Hence, if these

programs are to address water quality problems, the recommended practices must be evaluated for their impact on water quality, particularly in potentially vulnerable areas. 106 NAL Call. No.: QD1.A45 Groundwater and surface water risk assessments for proposed golf courses. Cohen, S.Z.; Durborow, T.E.; Barnes, N.L. Washington, D.C. : The Society; 1993. ACS Symposium series - American Chemical Society (522): p. 214-227; 1993. In the series analytic: Pesticides in urban environments: Fate and significance / edited by K.D. Racke and A.R. Leslie. Paper presented at the 203rd National Meeting of the American Chemical Society, April 5-10, 1992, San Francisco, California. Includes references. Language: English Descriptors: Hawaii; Massachusetts; Golf courses; Golf green soils; Herbicide residues; Insecticide residues; Leaching; Leachates; Runoff; Surface water; Water pollution; Groundwater pollution; Mathematical models; Simulation models; Risk; Fungicides; Pesticide residues; Fertilizers; Nitrogen Abstract: Proposed golf course developments usually require environmental impact statements in the U.S. Concerns about ground water, surface water, and near-shore coastal water quality and wetlands often require state-of-the-art risk assessments and complex computerized simulation modeling. It is extremely important to obtain site-specific data for these risk assessments. Thus soil sampling, test borings, stream surveys, and coastal surveys are often done. Daily weather records are obtained or generated. The new PRZM-VADOFT model pair is used for leaching assessments, even though nonlinear adsorption isotherms cannot be used. The SWRRBWQ model is difficult to use but it is appropriate for the modeling of complex drainage patterns at the basin and sub-basin scale, as with golf courses. Annual and storm-event runoff values are computed for pesticides, nutrients, runoff water, and sediments. It is best used for areas expected to experience appreciable runoff. EXAMS II provides useful predictions of stream water quality. An uncertainty analysis is a critical but often overlooked part of modeling. These results help fine tune proposed turf management programs and may indicate the need for design changes. Risk assessments in Hawaii are especially complex; they often indicate the need for detention basins. 107 NAL Call. No.: TD420.A1E5 Herbicide transport in rivers: importance of hydrology and geochemistry in nonpoint-source contamination. Squillace, P.J.; Thurman, E.M. Washington, D.C. : American Chemical Society; 1992 Mar. Environmental science & technology v. 26 (3): p. 538-545; 1992 Mar. Includes references.

Language: English Descriptors: Iowa; Minnesota; Herbicide residues; Water pollution; River water; Groundwater pollution; Concentration; Models; Overland flow 108 NAL Call. No.: S601.A34 High bed-low ditch system in the Pearl River Delta, South China. Ming, L.S.; Jian, L.R. Amsterdam : Elsevier; 1991 Jun14. Agriculture, ecosystems and environment v. 36 (1/2): p. 101-109; 1991 Jun14. Includes references. Language: English Descriptors: China; Delta soils; Alluvial soils; Deltas; Subtropics; Saccharum officinarum; Musa paradisiaca; Citrus reticulata; Oryza sativa; Sustainability; Ditches; High water tables; Soil depth; Roots; Growth; Erosion; Sediment; Nutrients; Losses from soil systems; Cycling; Flow; Models; Crop production; Agricultural byproducts; Irrigation water; Rain; Runoff water; Drainage water; Fertilizers; Dry matter accumulation; Decomposition; Crop residues; Nitrogen; Phosphorus pentoxide; Potassium; Nutrient content; Temporal variation; Dry season; Rainy season; Water quality; Organic matter 109 NAL Call. No.: TC163.I54 1992 Hydraulic and environmental modelling--estuarine and river waters proceedings of the Second International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters. Falconer, R. A.; Shiono, K.; Matthew, R. G. S. International Conference on Hydraulic and Environmental Modelling of Coastal, Estuarine, and River Waters 2nd : 1992 : University of Bradford. Aldershot, Hants, UK ; Brookfield, Vt. : Ashgate,; 1992. 2 v. : ill. ; 24 cm. Proceedings of a conference held at the University of Bradford, UK Sept. 22-24, 1992. Vol. 1 edited by F.A. Falconer, S.N. Chandler-Wilde, S.Q. Liu. Includes bibliographical references. Language: English Descriptors: Hydraulics; Water quality; Sediment transport 110 NAL Call. No.: 290.9 AM32T Hydraulic roughness coefficients as affected by random roughness. Gilley, J.E.; Finkner, S.C. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 May. Transactions of the ASAE v. 34 (3): p. 897-903; 1991 May. Includes references. Language: English

Descriptors: Nebraska; Hydraulic resistance; Runoff; Surface roughness; Tillage; Upland areas; Water flow; Simulation models Abstract: Random roughness parameters are used to characterize surface microrelief. In this study, random roughness was determined following six selected tillage operations. Random roughness measurements agreed closely with values reported in the literature. Surface runoff on upland areas is analyzed using hydraulic roughness coefficients. Darcy-Weisbach and Manning hydraulic roughness coefficients were identified in this investigation on each soil surface where random roughness values were determined. Hydraulic roughness coefficients were obtained from measurements of discharge rate and flow velocity. The experimental data were used to derive regression relationships which related Darcy- Weisbach and Manning hydraulic roughness coefficients to random roughness and Reynolds number. Random roughness values available in the literature can be substituted into the regression equations to estimate hydraulic roughness coefficients for a wide range of tillage implements. The accurate prediction of hydraulic roughness coefficients will improve our ability to understand and properly model upland flow hydraulics. 111 NAL Call. No.: 292.8 J82 Hydrogeologic controls on peatland development in the Malloryville Wetland, New York (USA). McNamara, J.P.; Siegel, D.I.; Glaser, P.H.; Beck, R.M. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Dec. Journal of hydrology v. 140 (1/4): p. 279-296; 1992 Dec. Includes references. Language: English Descriptors: New York; Peatlands; Swamps; Bogs; Fens; Hydrology; Geology; Vegetation; Plant communities; Ecology; Surface water; Water quality; Groundwater; Groundwater flow; Discharge; Upward movement; Mounds; Water table; Indicator species; Simulation models Abstract: The Malloryville Wetland Complex, a small kettle- hole peatland, contains a diversity of peatland types. The wetland has a 'rich' side that contains wetland vegetation associated with solute-rich, near-neutral pH (minerotrophic) water, and a 'poor' side containing vegetation that grows in solute-poor and acidic (ombrotrophic) water. Vertical head gradients at piezometer clusters located in the rich side clearly show that groundwater is moving upwards towards the land surface, consistent with the vegetation types and surface water quality. In contrast, vertical head gradients also show that groundwater is moving upward in the poor side even though the vegetation and surface water chemistry are not minerotrophic. An incipient raised bog in the center of the poor side is the only site where groundwater moves

consistently downward. A peat core collected at the bog center shows that the bog site was initially covered by minerotrophic vegetation, typically found in groundwater discharge zones, which was later replaced by ombrotrophic bog vegetation. Theoretical computer simulation experiments of the bog hydrogeologic setting through time suggest that the direction of vertical groundwater flow at the bog site permanently changed from up to down when a water table mound developed under a convex-shaped fen peat mound that probably formed because of differential peat accumulation. Ombrotrophic conditions and bog vegetation probably began when the fen water table mound grew sufficiently large enough to divert the upward movement of regional groundwater. The transition from rich to poor environments probably occurred when the wetland water table was substantially below the elevation of the surrounding regional water table. 112 NAL Call. No.: HD1750.W4 The impact of pollution controls on livestock--crop producers. Schnitkey, G.D.; Miranda, M.J. Bozeman, Mont. : Western Agricultural Economics Association; 1993 Jul. Journal of agricultural and resource economics v. 18 (1): p. 25-36; 1993 Jul. Includes references. Language: English Descriptors: Phosphorus; Runoff; Soil pollution; Pollution control; Livestock enterprises; Agricultural land; Crop production; Farmyard manure; Commercial soil additives; Environmental policy; Livestock numbers; Application methods; Returns; Mathematical models; Pig farming; Maize 113 NAL Call. No.: 290.9 AM32T Impact of random data errors on parameter estimation in hydrologic modeling. Borah, A.; Haan, C.T. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 May. Transactions of the ASAE v. 34 (3): p. 857-864; 1991 May. Includes references. Language: English Descriptors: Oklahoma; Hydrology; Rain; Runoff; Stream flow; Simulation models; Water resources; Watersheds Abstract: Parameter uncertainty in hydrologic models is due, in part, to random errors in input data used for calibration. This work investigates the impact of various error distributions associated with input data on the final estimated parameter values using three different estimation criteria. Errors in precipitation data were found to introduce more uncertainty into parameter estimates than errors in runoff data. Parameter uncertainty increased as the level of error introduced into input data increased. Correlated errors in the input data greatly increased the uncertainty associated with parameter estimates.

114 NAL Call. No.: 44.8 J822 Impact of Texas water quality laws on dairy income and viability. Leatham, D.J.; Schmucker, J.F.; Lacewell, R.D.; Schwart, R.B.; Lovell, A.C.; Allen, G. Champaign, Ill. : American Dairy Science Association; 1992 Oct. Journal of dairy science v. 75 (10): p. 2846-2856; 1992 Oct. Includes references. Language: English Descriptors: Texas; Dairy farms; Dairy wastes; Water quality; Law; Profitability; Estimated costs; Cash flow; Farm indebtedness; Risk; Survival; Mathematical models Abstract: A dairy waste management spreadsheet was developed and applied along with partial budgets and whole firm, Monte Carlo simulations for Texas dairies to evaluate the impact that Texas water quality laws have on dairy profitability and survival. Results showed that representative 300- and 720-cow dairies will incur additional annual costs of $60 and $81 per cow, respectively. Compliance with water quality laws reduces net farm income by 27 and 63% for 720-cow dairies with low and high debt positions, respectively. The probability of survival of the dairies with low debt was not affected by compliance. The probability of survival of firms with high debt positions decreased by 47 percentage points. Under the conditions modeled, net farm income for representative 300-cow dairies would be negative after compliance with water quality laws. 115 NAL Call. No.: 280.8 J822 Impact targets versus discharge standards in agricultural pollution management. Braden, J.B.; Larson, R.S.; Herricks, E.E. Ames, Iowa : American Agricultural Economics Association; 1991 May. American journal of agricultural economics v. 73 (2): p. 388-397; 1991 May. Includes references. Language: English Descriptors: Michigan; Fish; Lakes; Pollution; Losses; Habitats; Soil movement; Case studies; Watersheds; Pesticides; Water management; Environmental policy; Optimization; Mathematical models 116 NAL Call. No.: S494.5.S86S8 Impacts of uncertainty on policy costs of managing nonpoint source ground water contamination. Halstead, J.M.; Batie, S.S.; Taylor, D.B.; Heatwole, C.D.; Diebel, P.L.; Kramer, R.A. Binghamton, N.Y. : Food Products Press; 1991. Journal of sustainable agriculture v. 1 (4): p. 29-48; 1991. Includes references.

Language: English Descriptors: Virginia; Groundwater pollution; Nitrates; Stochastic models; Stochastic programming; Agricultural policy; Costs 117 NAL Call. No.: 290.9 AM32T The importance of precise rainfall inputs in nonpoint source pollution modeling. Rudra, R.P.; Dickinson, W.T.; Euw, E.L. von St. Joseph, Mich. : American Society of Agricultural Engineers; 1993 Mar. Transactions of the ASAE v. 36 (2): p. 445-450; 1993 Mar. Includes references. Language: English Descriptors: Ontario; Agricultural wastes; Losses from soil; Models; Pollutants; Rain; Soil properties Abstract: Rainfall data provide a prime input in nonpoint source pollution (nps) modeling. The sensitivity of model outputs to variations in the time step selected for rainfall data has been explored for two nps models, a field-scale continuous model, and an event-based watershed-scale model, for the temperate climatic conditions of Southern Ontario, Canada. This study has revealed that model outputs regarding runoff, soil loss and sediment yield, and calibrated parameters representing soil hydraulic properties and erosion characteristics are extremely sensitive to small variations in the rainfall time step. Model users must use caution therefore to take these variations into account during the calibration and application of such models. 118 NAL Call. No.: 290.9 AM32T Infiltration and runoff simulation on a plane. Stone, J.J.; Lane, L.J.; Shirley, E.D. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Jan. Transactions of the ASAE v. 35 (1): p. 161-170; 1992 Jan. Includes references. Language: English Descriptors: Erosion; Infiltration; Kinetics; Runoff; Simulation models; Computer software Abstract: A program which computes infiltration and the overland flow hydrograph on a single, homogeneous plane is described. Infiltration is computed by the Green and Ampt equation and the hydrograph is computed by a semi-analytical method of characteristics solution of the kinematic wave model for overland flow. Default parameter estimation values are supplied by the program for both the infiltration and hydrograph models. Use of the model as a tool for parameter selection is illustrated with rangeland rainfall simulator data.

119 NAL Call. No.: QH540.N3 Integrating database, spreadsheet, graphics, GIS, statistics, simulation models and expert systems: experiences with the RAISON system on microcomputers. Lam, D.C.L. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 26: p. 429-459; 1991. In the series analytic: Decision support systems: Water resources planning / edited by D.P. Loucks and J.R. da Costa. Proceedings of the NATO Advanced Research Workshop on Computer-Aided Support Systems for Water Resources, Research and Management, September 24-28, 1990, Ericeira, Portugal. Includes references. Language: English Descriptors: Water resources; Water management; Computer software; Computer graphics; Databases; Computer simulation; Simulation models; Expert systems; Microcomputers 120 NAL Call. No.: HC79.P55J6 Integrating fishery and water resource management: a biological model of a California salmon fishery. Fisher, A.C.; Hanemann, W.M.; Keeler, A.G. Duluth, Minn. : Academic Press; 1991 May. Journal of environmental economics and management v. 20 (3): p. 234-261; 1991 May. Includes references. Language: English Descriptors: California; Salmon; Fishery management; Water resources; Water management; Water flow; Hatcheries; Regulations; Water quality; Fresh water; Deltas; Dynamic models; Populations; Trends; Simulation; Quantitative analysis 121 NAL Call. No.: QH540.N3 The interface between GIS and hydrology. Wallis, J.R. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 26: p. 189-197; 1991. In the series analytic: Decision support systems: Water resources planning / edited by D.P. Loucks and J.R. da Costa. Proceedings of the NATO Advanced Research Workshop on Computer-Aided Support Systems for Water Resources, Research and Management, September 24-28, 1990, Ericeira, Portugal. Includes references. Language: English Descriptors: Water resources; Hydrology; Water management; Computer simulation; Simulation models; Computer hardware; Computer graphics; Computer software

122 NAL Call. No.: TD370.I575 1993 An Introduction to water quality modelling., 2nd ed.. James, A. Chichester ; New York : Wiley,; 1993. vi, 311 p. : ill. ; 25 cm. Includes bibliographical references and index. Language: English Descriptors: Water quality; Water quality management 123 NAL Call. No.: 23 AU783 Irrigation using groundwater for watertable control: a model of water and salt balance limitations. Salvich, P.G. Melbourne : Commonwealth Scientific and Industrial Research Organization; 1992. Australian journal of agricultural research v. 43 (1): p. 225-239; 1992. Includes references. Language: English Descriptors: New South Wales; Irrigation; Groundwater; Leaching; Recharge; Salinity; Simulation models 124 NAL Call. No.: 292.8 J82 Kinematic analysis of flood runoff for a small-scale upland field. Yomota, A.; Islam, M.N. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Aug15. Journal of hydrology v. 137 (1/4): p. 311-326; 1992 Aug15. Includes references. Language: English Descriptors: Japan; Reclamation; Runoff; Overland flow; Flooding; Sloping land; Upland areas; Mathematical models; Kinematics Abstract: In Japan, many sloping fields are being reclaimed by the Ministry of Agriculture, Forestry and Fisheries to increase the upland field areas. To predict the flood discharge from these fields, a study was undertaken from one reclaimed sloping field, in the Hiroshima prefecture, with an area of 4.55 ha. For modelling purposes, the widely used kinematic wave equations and method of characteristics were used. Rainfall and runoff data were collected for a period of 6 years (1984-1989) from the field, for both furrow and non- furrow conditions and were used in these analyses. Manning, Darcy and laminar resistance equations were used and Manning's equation was found to be the best of the three. Manning's roughness coefficient (n) for furrow flow and equivalent roughness (N) for non-furrow flow conditions were determined and are presented in tabular form. Application of the non- furrow flow equation to the furrow flow condition required

selecting an adequate equivalent roughness. Finally, verification of time of concentration, velocity of sheet or furrow flow and runoff coefficient were made both for furrow and non-furrow conditions, and these are graphically presented. 125 NAL Call. No.: TD201.A4 A kinematic model of infiltration and runoff generation in layered and sloped soils. Cabral, M.C.; Garrote, L.; Bras, R.L.; Entekhabi, D. Essex : Elsevier Science Publishers Ltd; 1992. Advances in water resources v. 15 (5): p. 311-324; 1992. Includes references. Language: English Descriptors: Infiltration; Rain; Movement in soil; Runoff water; Layered soils; Sloping land; Kinetics; Models 126 NAL Call. No.: 292.8 W295 Kinematic routing using finite elements on a triangular irregular network. Goodrich, D.C.; Woolhiser, D.A.; Keefer, T.O. Washington, D.C. : American Geophysical Union; 1991 Jun. Water resources research v. 27 (6): p. 995-1003; 1991 Jun. Includes references. Language: English Descriptors: Overland flow; Rain; Runoff; Watersheds; Topography; Kinematics; Mathematical models Abstract: Automated extraction of geometry for hydraulic routing from digital elevation models (DEM) is a procedure that must be easily accomplished for widespread application of distributed hydraulically based rainfall excess-runoff models. One-dimensional kinematic routing on a regular grid DEM is difficult due to flow division and convergence. Two- dimensional kinematic routing on a triangular irregular network (TIN) surmounts many of these difficulties. Because TIN DEMs typically require far fewer points to represent topography than regular grid DEMs, substantial computational economy is also realized. One-dimensional routing using vector contour data overcomes the grid-based routing disadvantages but often requires several orders of magnitude more storage points than a TIN. The methodology presented in this paper represents a compromise between slightly increased computational complexity and the economy of TIN topographic representation. We take the unique approach of subdividing each topographic triangle (TIN facet) into a set of coplanar triangular finite elements, performing routing on a single facet and then routing the resulting excess hydrograph to downstream facets and channels via upstream boundary conditions. Results indicate that shock conditions are readily handled, computed depths match analytic results to within +/-

3% and volume balances are typically within 1%. This modeling system illustrates the viability of kinematic routing over a TIN DEM derived directly from digital mapping data. 127 NAL Call. No.: S590.S62 Kinetics of soil chemical reactions--a theoretical treatment. Aharoni, C.; Sparks, D.L. Madison, Wis. : Soil Science Society of America; 1991. SSSA special publication series (27): p. 1-18; 1991. In the series analytic: Rates of soil chemical processes / edited by D.L. Sparks and D.L. Suarez. Proceedings of a Symposium, October 17, 1989, Las Vegas, Nevada. Includes references. Language: English Descriptors: Soil chemistry; Equations; Kinetics; Simulation models; Theory; Transport processes 128 NAL Call. No.: 292.8 J82 Laboratory and numerical investigations of immiscible multiphase flow in soil. Host-Madsen, J.; Jensen, K.H. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Jul. Journal of hydrology v. 135 (1/4): p. 13-52; 1992 Jul. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Petroleum; Flow; Hydraulics; Laboratory tests; Simulation models; Mathematical models; Quantitative analysis Abstract: Immiscible multiphase flow in porous media is investigated by laboratory experiments and numerical simulations. The hydraulic parameters used in mathematical models for multiphase flow are determined experimentally, and the interrelations between the individual parameters are analysed. The experimental data support the applicability of analytical closed-form expressions for the constitutive relations, and a scaling procedure is verified in which the interfacial tensions are used to derive scaling factors. These simplifications in the parameter requirements are very valuable from an engineering point of view. A two-dimensional plexiglass flume is used for studying the flow of lighter- than-water, non-aqueous phase liquids (LNAPL) in sandy porous media. The migration of the LNAPL is observed both in the unsaturated zone and in the saturated zone at the bottom of the flume. A dual-gamma attenuation system is used for measuring the phase saturations of organic fluid, water, and air simultaneously without disturbing the flow. This permits a two-dimensional quantitative determination of the LNAPL plume in contrast to many earlier qualitative studies. A black oil reservoir model is used to simulate immiscible multiphase flow. By using the parameter estimation methods presented for establishing the constitutive relations, the model is applied to the simulation of the laboratory experiments. The

experimental and numerical results compare reasonably well, thus supporting the adopted model formulation. 129 NAL Call. No.: 100 M38H (1) no.738 Landscape planning for watershed protection the first step. la Cour, Niels; Fabos, Julius Gy; Ahern, Jack Massachusetts Agricultural Experiment Station Amherst, Mass. : Massachusetts Agricultural Experiment Station, College of Food and Natural Resources, University of Massachusetts at Amherst,; 1992. x, 77 p. : ill., maps ; 23 cm. (Research bulletin (Massachusetts Agricultural Experiment Station) ; no. 738.). Received for publication August 1991. Winter 1992. Includes bibliographical references (p. 75-77). Language: English; English Descriptors: Watershed management; Regional planning; Geographic information systems 130 NAL Call. No.: 292.8 W295 The Las Cruces Trench site: characterization, experimental results, and one-dimensional flow predictions. Wierenga, P.J.; Hills, R.G.; Hudson, D.B. Washington, D.C. : American Geophysical Union; 1991 Oct. Water resources research v. 27 (10): p. 2695-2705; 1991 Oct. Includes references. Language: English Descriptors: New Mexico; Soil water; Water flow; Solutes; Transport processes; Infiltration; Semiarid soils; Soil variability; Wetting front; Saturated hydraulic conductivity; Deterministic models; Prediction Abstract: A comprehensive field trench study was conducted in a semiarid area of southern New Mexico to provide data to test deterministic and stochastic models of vadose zone flow and transport. A 4 m by 9 m area was irrigated with water containing a tracer using a carefully controlled drip irrigation system. The area was heavily instrumented with tensiometers and neutron probe access tubes to monitor water movement and with suction tubes to monitor solute transport. Approximately 600 disturbed and 600 core samples of soil were taken to support deterministic and stochastic characterization of the soil water hydraulic parameters. The core sample-based saturated hydraulic conductivities ranged from 1.4 to 6731 cm/d with a mean of 533 cm/d and a standard deviation of 647 cm/d, indicating significant spatial variability. However, visual observation of the wetting front on the trench wall shows no indication of preferential flow or water flow through visible root channels and cracks. The tensiometer readings and the neutron probe measurements also suggest that the wetting front moves in a fairly homogeneous fashion despite the significant spatial variability of the saturated hydraulic conductivity. In addition to the description of the experiment

and the presentation of the experimental results, predictions of simple one-dimensional uniform and layered soil deterministic models for infiltration are presented and compared to field observations. These models are presented here to provide a base case against which more sophisticated deterministic and stochastic models can be compared in the future. The results indicate that the simple models give adequate predictions of the overall movement of the wetting front through the soil during infiltration. However, the models give poor predictions of point values for water content due to the spatial variability of the soil. Comparisons between the one-dimensional infiltration model predictions and field observations show that the use of t 131 NAL Call. No.: 292.8 J82 A linear cascade model for predicting transport of dissolved agrochemicals by surface runoff. Wallach, R. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Sep. Journal of hydrology v. 126 (3/4): p. 207-224; 1991 Sep. Includes references. Language: English Descriptors: Agricultural chemicals; Runoff water; Surface layers; Transport processes; Flow; Mathematical models Abstract: A cascade-based model is used to predict the dissolved chemical concentration profile at the effluent of a field. The source of chemicals is the soil surface layer, from which the chemicals are transferred to the surface runoff and transported to the field outlet. The model applies a cascade of perfectly mixed cells analogous to an equivalent surface runoff water and soil surface laver. Each cell is made of two interconnected units, where the upper unit represents the runoff water and the lower unit represents the soil bulk. Chemical transfer between the two units is controlled by the convective mass-transfer process through the laminar boundary laver of the surface runoff flow. The cells are interconnected through their upper units by runoff water flow. The lower unit applies a perfectly mixed reactor analog to an equivalent and homogeneous soil layer of uniform concentration near the soil surface. called the effective depth of transfer (EDT). The expression for the concentration within the EDT is simplified and agrees well with the soil surface concentration as determined by an analytical solution of the one-dimensional diffusion equation for the limiting case of no infiltration. The number of cells in the cascade is a measure of the extent of axial mixing in runoff flow where the limiting cases are: (1) a perfective mixed system represented by one cell, and (2) a zero-mixing system (plug flow) represented by a cascade made of an infinite number of cells. The distribution of chemical concentrations for these two extreme cases and for other flows with varying degrees of mixing are presented.

132 NAL Call. No.: 292.8 W295 Linear transport models for adsorbing solutes. Roth, K.; Jury, W.A. Washington : American Geophysical Union, 1965-; 1993 Apr. Water resources research v. 29 (4): p. 1195-1203; 1993 Apr. Includes references. Language: English Descriptors: Transport processes; Movement in soil; Adsorption; Solutes; Linear models Abstract: A unified linear theory for the transport of adsorbing solutes through soils is presented and applied to analyze movement of napropamide through undisturbed soil columns. The transport characteristics of the soil are expressed in terms of the travel time distribution of the mobile phase which is then used to incorporate local interaction processes. This approach permits the analysis of all linear transport processes, not only the small subset for which a differential description is known. From a practical point of view, it allows the direct use of measured concentrations or fluxes of conservative solutes to characterize the mobile phase without first subjecting them to any model. For complicated flow regimes, this may vastly improve the identification of models and estimation of their parameters for the local adsorption processes. 133 NAL Call. No.: TD196.M4B56 1992 Long-term behavior of heavy metals in agricultural soils: a simple analytical model. Harmsen, K. Boca Raton : Lewis Publishers; 1992. Biogeochemistry of trace metals / edited by Domy C. Adriano. p. 217-247; 1992. (Advances in trace substances research). Includes references. Language: English Descriptors: Agricultural soils; Heavy metals; Solubility; Leaching; Uptake 134 NAL Call. No.: TD426.J68 Long-term effects of soil heterogeneity on cadmium behavior in soil. Boekhold, A.E.; Zee, S.E.A.T.M. van der Amsterdam : Elsevier; 1991 Jun. Journal of contaminant hydrology v. 7 (4): p. 371-390; 1991 Jun. Includes references. Language: English Descriptors: Soil pollution; Cadmium; Behavior; Sandy soils; Uptake; Hordeum vulgare; Deterministic models; Soil; Physicochemical properties; Profiles; Leaching; Heterogeneity; Equations

135 NAL Call. No.: 292.9 AM34 Low-input agriculture as a ground water protection strategy. Diebel, P.L.; Taylor, D.B.; Batie, S.S.; Heatwole, C.D. Bethesda, Md. : American Water Resources Association; 1992 Jul. Water resources bulletin v. 28 (4): p. 755-761; 1992 Jul. Includes references. Language: English Descriptors: Virginia; Groundwater pollution; Water quality; Farm inputs; Farming systems; Profitability; Economic analysis; Mathematical models Abstract: Protection of ground water quality is of considerable importance to local, state, and federal governments. This study uses a 15-year mathematical programming model to evaluate the effectiveness of low-input agriculture, under alternative policy scenarios, as a strategy to protect ground water quality in Richmond County, Virginia. The analysis considers eight policy alternatives: cost-sharing for green manures, two restrictions on atrazine applications levels, chemical taxation, a restriction on potential chemical and nitrogen levels in ground water only and in surface and ground water, and two types of land retirement programs. The CREAMS and GLEAMS models were used to estimate nitrate and chemical leaching from the crop root zone. The economic model evaluates production practices, policy constraints, and water quality given a long-term profit maximizing objective. The results indicate that low-input agriculture alone may not be an effective groundwater protection strategy. The policy impacts include partial adoption of low-input practices, land retirement, and the substitution of chemicals. Only mandatory land retirement policies reduced all chemical and nutrient loadings or ground water; however, they did not promote the use of low-input agricultural practices. 136 NAL Call. No.: 56.8 SO3 Lysimeter study of anion transport during steady flow through layered coarse-textured soil profiles. Jacobsen, O.H.; Leij, F.J.; Van Genuchten, M.T. Baltimore, Md. : Williams & Wilkins; 1992 Sep. Soil science v. 154 (3): p. 196-205; 1992 Sep. Includes references. Language: English Descriptors: Coarse textured soils; Layered soils; Unsaturated flow; Soil water movement; Soil variability; Transport processes; Chlorine; Nitrate; Mathematical models; Soil water retention 137 NAL Call. No.: TD420.A1P7 Management of water resources and eutrophication in the

Federal District of Brazil. Somlyody, L.; Altafin, I. Oxford : Pergamon Press; 1992. Water science and technology : a journal of the International Association on Water Pollution Research and Control v. 26 (7/8): p. 1813-1822; 1992. In the series analytic: Water Quality International '92. Part 4 / edited by M. Suzuki, et al. Proceedings of the Sixtennth Biennial Conference of the International Association on Water Pollution Research and Control, held May 24-30, 1992, Washington, D.C. Includes references. Language: English Descriptors: Brazil; Reservoirs; Eutrophication; Water purification; Sewage; Waste treatment; Algae; Biomass production; Water resources; Management; Water quality; Models 138 NAL Call. No.: 56.8 J822 Managing the land: a technology perspective. Shaw, R.R. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Nov. Journal of soil and water conservation v. 46 (6): p. 406-408; 1991 Nov. Language: English Descriptors: Land management; Technology transfer; Remote sensing; Information systems; Computer software; Usda; Water management; Soil conservation 139 NAL Call. No.: FUQL628.F6M371 1992 Marine resources geographic information system and fishery resources final report. Haddad, Kenneth D. Florida Marine Research Institute, Florida Office of Coastal Management St. Petersburg, Fla. : Dept. of Natural Resources, Division of Marine Resources, Florida Marine Research Institute,; 1992. 1 v. (unpaged) : ill., maps (some col.) ; 28 cm. January, 1992. Funds for this project were provided by the Department of Environmental Regulation, Office of Coastal Management... Includes bibliographical references. Language: English; English Descriptors: Information storage and retrieval systems; Marine resources; Watershed management; Fishery management; Geographic information systems 140 NAL Call. No.: 56.9 SO3 Mathematical analysis of one-dimensional solute transport in a layered soil profile. Leij, F.J.; Dane, J.H.; Van Genuchten, M.T.

Madison, Wis. : The Society; 1991 Jul. Soil Science Society of America journal v. 55 (4): p. 944-953; 1991 Jul. Includes references. Language: English Descriptors: Layered soils; Movement in soil; Leaching; Contaminants; Solutes; Profiles; Interface; Soil boundaries; Subsurface barriers; Sand; Clay; Mathematical models; Qualitative techniques; Errors Abstract: Solute transport studies involving layered media are important for investigating how restricting layers affect rates of solute migration in the soil profile and, more generally, for examining the influence of soil heterogeneity on solute transport. Analytical solutions of the one- dimensional advection-dispersion equation (ADE) were obtained with the help of Laplace transforms for transport in a two- layered soil profile. Assuming that the layers are, in effect, semi-infinite, solutions were obtained for first-type (constant concentration) and third-type (constant flux) conditions at both the inlet boundary and the interface of the two layers. Concentration profiles were also obtained for a finite first layer via numerical inversion of the Laplace transform solution, using a third-type condition at the inlet, and, simultaneously, a first- and third-type condition at the interface. Volume-averaged or resident-type concentrations were used in all cases. First-type conditions did not meet our criterion of mass conservation, whereas third-type conditions caused discontinuities in the concentration at the interfaces of layers with differing transport parameters. The concentration at the interface was found to be continuous, and no mass-balance error occurred, when first- and third-type conditions were imposed simultaneously at the interface. Several example calculations show the effect of soil layering on solute transport in a one-dimensional soil profile. 141 NAL Call. No.: 292.8 W295 A mathematical model of hillslope and watershed discharge. Stagnitti, F.; Parlange, J.Y.; Steenhuis, T.S.; Parlange, M.B.; Rose, C.W. Washington, D.C. : American Geophysical Union; 1992 Aug. Water resources research v. 28 (8): p. 2111-2122; 1992 Aug. Includes references. Language: English Descriptors: Connecticut; Watersheds; Water flow; Soil water; Slopes; Soil water balance; Soil physical properties; Soil depth; Runoff; Seepage; Evaporation; Water yield; Water holding capacity; Saturated hydraulic conductivity; Catchment hydrology; Mathematical models; Prediction Abstract: A mathematical water balance model describing major hydrological processes operating within wet forested watersheds is proposed. The model is capable of predicting

hillslope and watershed discharge, evapotranspiration demands, hillslope moisture status, and surface and subsurface flow rates. It is based on soil physical principles and requires the following input variables: average hillslope angle and width, average soil depth, precipitation, average daily evaporation rates, effective saturated hydraulic conductivity, soil moisture holding capacity and initial moisture content. These variables are often easily measured from field studies. However, in some cases, the absence of field data may require that some of the variables in the model, e.g., saturated hydraulic conductivity, be estimated or calibrated from hillslope hydrograph records. The watershed model is composed of two submodels: a storage model and a hillslope model. The storage model describes the dynamic variation in water table elevation in recharge zones and the hillslope model is used to predict runoff and seepage through flow from surrounding hillsides. Application of the model is illustrated on a small watershed located in North Madison, Connecticut. 142 NAL Call. No.: QH540.N3 A mathematical systems model of nitrate contamination. Dkstein, L.; Head, K.L.; Bogardi, I. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 30: p. 455-476; 1991. In the series analytic: Nitrate contamination: Exposure, consequence, and control / edited by I. Bogardi and R.D. Kuzelka. Proceedings of the NATO Advanced Research Workshop on Nitrate Contamination: Exposure, Consequences, and Control, September 9-14, 1990, Lincoln, Nebraska. Includes references. Language: English Descriptors: Nitrate; Nitrate fertilizers; Groundwater pollution; Drinking water; Contamination; Carcinoma; Risk; Mathematical models; Epidemiology; Simulation models 143 NAL Call. No.: QH545.A1E58 Matrix decision procedure to assess new pesticides based on relative groundwater leaching potential and chronic toxicity. Britt, J.K.; Dwinell, S.E.; McDowell, T.C. Tarrytown, N.Y. : Pergamon Press; 1992. Environmental toxicology and chemistry v. 11 (5): p. 721-728; 1992. Includes references. Language: English Descriptors: Florida; Pesticides; Public health; Toxicity; Environment; Environmental impact; Groundwater; Groundwater pollution; Leaching; Registration; Indexes; Ranking; Environmental protection; Subtropics; Models 144 NAL Call. No.: TD224.I3P75 1991 McCook Reservoir water quality model numerical model

investigation. Price, Richard E.; Tillman, Dottie United States, Army, Corps of Engineers, Chicago District, U.S. Army Engineer Waterways Experiment Station Vicksburg : Miss. : U.S. Army Engineer Waterways Experiment Station ; Springfield, Va. : Available from National Technical Information Service,; 1991. 48 p. : ill. ; 28 cm. (Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-91-17.). September 1991. Cover title. Bibliography: p. 46-48. Language: English Descriptors: McCook Reservoir (Ill.); Reservoirs; Water quality; Flood dams and reservoirs 145 NAL Call. No.: QH84.8.B46 Measured and simulated denitrification activity in a cropped sandy and loamy soil. Vinther, F.P. Berlin : Springer International; 1992. Biology and fertility of soils v. 14 (1): p. 43-48; 1992. Includes references. Language: English Descriptors: Denmark; Hordeum vulgare; Lolium multiflorum; Denitrification; Leaching; Losses from soil systems; Measurement; Nitrogen; Soil temperature; Soil water; Long term experiments; Loam soils; Sandy soils 146 NAL Call. No.: SB610.2.B74 Measurement and modelling of pesticide residues at Rosemaund Farm. Williams, R.J.; Brooke, D.N.; Glendinning, P.J.; Matthiessen, P.; Mills, M.J.; Turnbull, A. Surrey : BCPC Registered Office; 1991. Brighton Crop Protection Conference-Weeds v. 2: p. 507-514; 1991. Conference held November 18-21, 1991, Brighton, England. Includes references. Language: English Descriptors: England; Pesticide residues; Water pollution; Models 147 NAL Call. No.: S541.5.W2R47 Measuring economic benefits of water pollution abatement in an irrigated river basin. Willis, D.; May, L.; Gutema, Y. Pullman, Wash. : The Center; 1992. Research bulletin XB - Washington State University, Agricultural Research Center (1019): 24 p.; 1992. Includes references. Language: English

Descriptors: Washington; Rivers; Water pollution; Water quality; Water recreation; Fishing; Irrigation; Pollutants; Environmental impact; Water purification; Economic impact; Mathematical models 148 NAL Call. No.: 56.9 SO3 Measuring field variability of disturbed soils for simulation purposes. Finke, P.A.; Bouma, J.; Stein, A. Madison, Wis. : The Society; 1992 Jan. Soil Science Society of America journal v. 56 (1): p. 187-192; 1992 Jan. Includes references. Language: English Descriptors: Netherlands; Disturbed soils; Soil variability; Profiles; Spatial variation; Soil surveys; Thickness; Determination; Soil structure; Porosity; Soil texture; Soil organic matter; Soil water content; Soil water retention; Hydraulic conductivity; Nitrate; Leaching; Soil morphology; Simulation models Abstract: Spatial variation of soil profiles disturbed by leveling was inventoried on a field scale to obtain representative data for simulation purposes. Depth of occurrence, thickness, and morphology of functional layers, which are different pedogenetic horizons with comparable soil physical properties, were considered to be regionalized variables. The layers served as carriers of physical information, such as water-retention and hydraulic- conductivity characteristics and organic-matter content. An impression of the variability within each layer was obtained by six fold sampling. Spatial variability, expressed by variations in thickness of functional layers, was inventoried in a two-step soil survey. First, semivariograms were constructed using data obtained following a nested sampling scheme supplemented by a nugget estimation procedure. Variograms were used to evaluate cost/quality ratios at varying potential grid sampling densities, using the root of the prediction error variance (RPEV) to compare quality of interpolations. Based on these evaluations and a sequential sampling test, a grid mesh of 12 m was chosen. Second, a grid soil survey and an independent quality test were done, in which root mean square errors (RMSE) on test points were compared with RPEV. The RPEV to RMSE ratios varied between 0.7 and 1.1 for the sampled grid mesh, and had comparable values for other grid meshes. Estimations on test points by an hypothesized spatial mean, based on 26 measurements by a sequential sampling method, produced RMSE values not significantly different from RMSE values from kriging interpolations. However, sequential sampling required 26 observations whereas kriging required 153, a saving of 93%. 149 NAL Call. No.: 56.8 J823 Measuring the diffusion coefficient of rhizosphere exudates in

soil. I. The diffusion of non-sorbing compounds. Darrah, P.R. Oxford : Blackwell Scientific Publications; 1991 Sep. The Journal of soil science v. 42 (3): p. 413-420; 1991 Sep. Includes references. Language: English Descriptors: Brown earths; Root exudates; Diffusivity; Measurement; Solutes; Transport processes; Rhizosphere; Mathematical models; Sorption Abstract: A quick, convenient and robust method is presented for measuring the effective diffusion coefficients of non- sorbing solutes in soil. The method estimates the effective diffusion coefficient from a measured diffusion profile by optimizing the solution of a numerical simulation model describing the experimental system. The method was used to measure the effective diffusion coefficients of compounds found in root exudates. 150 NAL Call. No.: 56.8 J823 Measuring the diffusion coefficients or rhizosphere exudates in soil. II. The diffusion of sorbing compouds. Darrah, P.R. Oxford : Blackwell Scientific Publications; 1991 Sep. The Journal of soil science v. 42 (3): p. 421-434; 1991 Sep. Includes references. Language: English Descriptors: Brown earths; Root exudates; Diffusivity; Measurement; Transport processes; Rhizosphere; Sorption isotherms; Mathematical models; Simulation models; Sorption; Solutes Abstract: A mathematical model was developed which was capable of simulating the diffusion of compounds with a concentration-dependent diffusion coefficient, by virtue of their sorption on the solid phase of the soil. Methods were developed which allowed the sorption characteristics and the effective diffusion coefficient of several organic compounds to be inferred from their measured diffusion profiles. 151 NAL Call. No.: 56.8 J823 A method for assessing the goodness of computer simulation of soil processes. Whitmore, A.P. Oxford : Blackwell Scientific Publications; 1991 Jun. The Journal of soil science v. 42 (2): p. 289-299; 1991 Jun. Includes references. Language: English Descriptors: Soil testing; Bromide; Diffusion; Nitrate nitrogen; Leaching; Movement in soil; Computer simulation;

Simulation models; Assessment; Evaluation; Statistical analysis; Statistical data; Measurement; Variation; Experimental design; Replication; Temporal variation; Mathematics; Errors Abstract: Any satisfactory computer simulation model of a soil process must match actual behaviour in the laboratory or field; a model can be evaluated by how well it does so. This paper describes a method for assessing models using anion diffusion and nitrate leaching as examples. The method partitions the sum of squares of the differences between measurement and simulation into two components, one calculated from the differences between the simulation and the mean of replicate measurements (the 'lack of fit'), and the other calculated from the variance within each set of replicate measurements (the 'pure error'). If the former is not significantly larger than the latter than the data present no grounds for rejecting the model. Where a model simulates the change in a process with time the method can also take account of how experimental error in the initial measurements affects the goodness of fit of the simulation of subsequent measurements. The method is particularly valuable where it is difficult or costly to take many replicate measurements, such as often happens in soil science or agriculture; nonetheless, some replicates must be taken. 152 NAL Call. No.: 56.8 SO3 A method for studying nonequilibrium sorption during transport of pesticides in soil. Kookana, R.S.; Gerritse, R.G.; Aylmore, L.A.G. Baltimore, Md. : Williams & Wilkins; 1992 Nov. Soil science v. 154 (5): p. 344-349; 1992 Nov. Includes references. Language: English Descriptors: Soil analysis; Linuron; Simazine; Sorption; Kinetics; Transport processes; Simulation models; Saturated conditions; Movement in soil 153 NAL Call. No.: QH540.J6 Microlysimeter soil columns for evaluating pesticide movement through the root zone. Fermanich, K.J.; Daniel, T.C.; Lowery, B. Madison, Wis. : American Society of Agronomy; 1991 Jan. Journal of environmental quality v. 20 (1): p. 189-195; 1991 Jan. Includes references. Language: English Descriptors: Pesticides; Leaching; Lysimetry; Measurement; Movement in soil; Simulation models; Soil temperature; Soil water; Water balance Abstract: Field approaches to studying pesticide movement are

subject to numerous variables of the environment, many of which are difficult and expensive to monitor. This study describes the design, construction, operation, and performance of intact microlysimeter soil (Plainfield loamy sand-mixed, mesic, Typic Udipsamment) columns used to examine the mobility of two insecticides through soil from two tillage plots (conventional-moldboard plow and no-till tillage). Field leaching conditions were approximated by simulating a moisture and temperature regime characteristic of a natural soil profile. Measured daily and seasonal temperature fluctuated according to a pattern characteristic of a field soil. Evapotranspiration (ET) from the soil columns was 61% of the total water applied and was nearly equal to the ET measured (63%) from field lysimeters of this soil planted to corn (Zea mays L.). Variation in cumulative drainage was small, total drainage from all columns was within a range of 3.9 cm. There was no significant difference in the transport of bromide (conservative tracer) through columns from the two tillage plots. Bromide leachate loss was 62 and 63% of the amount applied for conventional-moldboard plow and no-till columns, respectively. Intact soil columns established in a microlysimeter fashion provided a means to compare the movement of agricultural chemicals under controlled conditions in the greenhouse that approximate conditions/processes in the field. 154 NAL Call. No.: 292.8 W295 Microtargeting the acquistion of cropping rights to reduce nonpoint source water pollution. Kozloff, K.; Taff, S.J.; Wang, Y. Washington, D.C. : American Geophysical Union; 1992 Mar. Water resources research v. 28 (3): p. 623-628; 1992 Mar. Includes references. Language: English Descriptors: Minnesota; Agricultural land; Land use; Land management; Watersheds; Water pollution; Water quality; Erosion; Sediment yield; Simulation models; Cost effectiveness analysis Abstract: Targeting cropland retirement programs to reduce agricultural nonpoint source pollution is accomplished by employing disaggregated information about physical and economic factors that influence the benefits and costs of adopting specific erosion control practices on specific land parcels. The agricultural nonpoint source (AGNPS) model is used in a Minnesota watershed to simulate the relative effectiveness of alternative targeting schemes with respect to budget outlays for annual payments to landowners, reduction in downstream sediment yield and nutrient loss, and reduction in on-site erosion. Cost-effectiveness increased with information on economic factors (the opportunity cost of retiring a parcel of land) as well as on physical factors (contribution of a parcel to downstream sediment yield). The marginal cost- effectiveness of all schemes decreased as the enrolled

proportion of watershed land increased. 155 NAL Call. No.: TD403.G7 Model development and simulation of bioremediation in soil beds with aggregates. Dhawan, S.; Erickson, L.E.; Fan, L.T. Dublin, Ohio : Ground Water Pub. Co; 1993 Mar. Ground water v. 31 (2): p. 271-284; 1993 Mar. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Organic compounds; Biodegradation; Simulation models; Soil; Aggregates Abstract: One method of remediating contaminated soil and ground water is through management of the subsurface environment so that indigenous microorganisms can biodegrade organic contaminants. Modeling and simulation offer promising means of assessing the migration and attenuation of such contaminants being treated in situ in the subsurface. In this paper, a macropore flow model has been developed to account for bioremediation in the interstitial spaces among soil aggregates. This model has been combined with another bioremediation model which accounts for diffusion and biodegradation in the micropores and soil particles in the aggregates. The combined model comprises a system of six coupled equations, of which three are nonlinear ordinary differential equations and three are nonlinear partial differential equations. Dimensional analysis of these equations has yielded useful dimensionless parameters for evaluating the relative significance of each mechanism in remediation. Numerical experiments have been conducted to evaluate the effects of initial contaminant concentration, aggregate size, and soil-water partition factor. The total time of remediation has been found to depend on the rate at which contaminants are consumed within the large aggregates which, in turn, depends on the biodegradation kinetics and the rates of diffusion of substrate and oxygen in the aggregates. For soil with aggregates whose radius is 1 cm or larger, the results of simulation indicate that the remediation time for the aggregates is significantly longer compared to the corresponding result for homogeneous soil. For contaminants with large partition coefficients, the estimated time for remediation achieved through microbial oxidation in situ is much shorter than that achieved through purely diffusional transport of the contaminants out of the soil bed. 156 NAL Call. No.: TD419.R47 A model for evaluating the impacts of land application of organic waste on runoff water quality. Deizman, M.M.; Mostaghimi, S. Alexandria, Va. : The Federation; 1991 Jan. Research journal of the Water Pollution Control Federation v. 63 (1): p. 17-27; 1991 Jan. Includes references.

Language: English Descriptors: Organic wastes; Application to land; Organic fertilizers; Runoff water; Water pollution; Soil pollution; Simulation models; Agricultural land; Nitrogen; Transformation; Losses 157 NAL Call. No.: 292.8 J82 A model for oxygen transport and consumption in the unsaturated zone. Refsgaard, J.C.; Christensen, T.H.; Ammentorp, H.C. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Dec. Journal of hydrology v. 129 (1/4): p. 349-369; 1991 Dec. Includes references. Language: English Descriptors: Soil water; Soil air; Oxygen transport; Oxygen consumption; Solutes; Transport processes; Unsaturated flow; Diffusion; Diffusivity; Soil water content; Crumbs; Size; Denitrification; Mathematical models Abstract: An oxygen transport and consumption model has been developed as a submodel to a general numerical model for solute transport in the unsaturated zone. The model comprises diffusive and convective transport of oxygen in soil air, convective transport and oxygen consumption in free water, and diffusive transport and a constant-rate oxygen consumption in the water-saturated soil crumbs. The model also estimates the anaerobic fraction of the water-saturated crumbs where no oxygen consumption takes place. The model dynamics and applicability are illustrated using the examples of the operation of a waste water infiltration plant and of anaerobic zones in the soil of importance for modelling denitrification. 158 NAL Call. No.: 56.9 SO3 Model of boron movement in soils. Shani, U.; Dudley, L.M.; Hanks, R.J. Madison, Wis. : The Society; 1992 Sep. Soil Science Society of America journal v. 56 (5): p. 1365-1370; 1992 Sep. Includes references. Language: English Descriptors: Calcareous soils; Boron; Movement in soil; Transport processes; Simulation models; Mathematical models Abstract: A model to predict B transport in calcareous soils is presented. The model considers one-dimensional, non-steady- state soil water flow, convective-dispersive solute transport of both noninteracting salt (i.e., Cl) and B. The model was designed to simulate field situations including infiltration, evaporation, transpiration, drainage, and water extraction by plant roots. Predictions were compared with field B profiles and column leaching studies. The model accurately simulated

Bleaching from columns of B-contaminated soils under saturated and steady-state water flow conditions. Model simulations, Udder conditions of transient water flow and transient B concentrations in a column study, were in reasonable agreement with the measured values. Model predictions were also compared with evolving soil soluble-B profiles determined in a field study (5-7 yr) with repeated irrigation with saline, B- containing waters. Computed results of the B accumulation in the upper portion of the soil profile, and of the B front, were in good agreement with measured data. 159 NAL Call. No.: TD172.J6 Model simulation and regional pollution reduction strategies. Shirmohammadi, A.; Shoemaker, L.L.; Magette, W.L. New York, N.Y. : Marcel Dekker; 1992 Dec. Journal of environmental science and health : Part A : Environmental science and engineering v. 27 (8): p. 2319-2336; 1992 Dec. Includes references. Language: English Descriptors: Maryland; Soil pollution; Groundwater pollution; Nitrogen; Losses; Erosion control; Coastal plains; Mountain areas; Plains; Tillage; Practice; Simulation models; Cultivation; Cropping systems; Fertilizers; Application methods 160 NAL Call. No.: 292.8 W295 Modeling base flow soil water residence times from deuterium concentrations. Stewart, M.K.; McDonnell, J.J. Washington, D.C. : American Geophysical Union; 1991 Oct. Water resources research v. 27 (10): p. 2681-2693; 1991 Oct. Includes references. Language: English Descriptors: New Zealand; Soil water; Transport processes; Rain; Water flow; Stream flow; Watersheds; Deuterium; Measurement; Mathematical models Abstract: Three approaches to determining mean soil water residence times in a steep headwater catchment were investigated. The deuterium concentrations of soil water collected from 11 suction cup samplers at the Maimai M8 catchment were determined weekly for 14 weeks and the results compared with those of rainfall in the same period. Deuterium variations in the suction samples were considerably delayed and diminished compared with the rainfall, indicating significant storage times and mixing with soil water. Soil matrix water at shallow levels (approximately 200 mm depth) in unsaturated soils was relatively responsive to fresh input, but deeper water and water near the stream subject to occasional water table rises showed much less variation. Steady state and non-steady state exponential models gave similar mean residence times, ranging from 12 to more than 100

days for different locations. Three groups of soil water response were defined, comprising shallow, medium and deep (near-stream) soil locations based on the mean residence times. The nonsteady models revealed considerable week-to-week and longer variations in mean residence time for shallow soil (SL4), but indicated that steady state models could adequately represent the system in the overall period investigated. In the third approach, model types and parameters that gave the best fits to the soil water deuterium concentrations were determined. Exponential and especially dispersion models were the most satisfactory. Weighting the input (rainfall delta D) partially or fully with the amount of rainfall gave much worse fits than with the unweighted input, showing that much of the rainfall bypasses the soil matrix. The best fitting dispersion model (designated DM2) yielded the most accurate mean residence times: 13 days for shallow soil (SL4), 42 days for soil at 400 mm depth (SL5), both at midslope locations, and 63 days for soil at 800 mm depth near the stream (SL2). Capillary flow was important for the unsaturated s 161 NAL Call. No.: KyUThesis 1991 Storm Modeling dynamic rill networks from random surfaces on moderate slopes. Storm, Daniel E. 1991; 1991. 2 v. : ill. ; 28 cm. Includes vita and abstract. Includes bibliographic refernces (l. 499-508). Language: English Descriptors: Soil erosion; Drainage; Probabilities 162 NAL Call. No.: 292.8 W295 Modeling infiltration for multistorm runoff events. Smith, R.E.; Corradini, C.; Melone, F. Washington, D.C. : American Geophysical Union; 1993 Jan. Water resources research v. 29 (1): p. 133-144; 1993 Jan. Includes references. Language: English Descriptors: Infiltration; Mathematical models; Soil water movement; Redistribution; Runoff; Soil water content; Rain; Storms; Simulation Abstract: We present a relatively simple analytical/conceptual model for rainfall infiltration during complex storms. It is an approximate but physically based model which can treat intervals of either no rain, low rain, or evaporation. The infiltration model is based on the very general three-parameter analytic model of Parlange et al. (1982), extended to treat soils with very high initial water content. The redistribution model is based on profile extension with shape similarity. A wide range of soil types can be simulated. The model is tested by comparison with numerical solutions of Richards's equation carried out for a

variety of events upon four selected soils. The model simulates the solution to Richards's equation quite accurately, provided basic soil retention relations are parametrically represented. It simulates redistribution particularly well for redistribution intervals up to 20 hours. The model usefulness in comparison with the common and simple approach which disregards soil water redistribution is also shown. 163 NAL Call. No.: 292.8 W295 Modeling long-term solute transport in drained unsaturated zones. Kandil, H.; Miller, C.T.; Skaggs, R.W. Washington, D.C. : American Geophysical Union; 1992 Oct. Water resources research v. 28 (10): p. 2799-2809; 1992 Oct. Includes references. Language: English Descriptors: Unsaturated flow; Transport processes; Solutes; Drained conditions; Soil water balance; Water table; Water quality; Prediction; Simulation; Mathematical models; Algorithms Abstract: Long-term assessment of solute transport in the unsaturated zone is an important consideration for irrigation management, pesticide management, and subsurface contaminant restoration analysis and design. Mathematical models are often used to perform such analyses. Modeling fluid flow and solute transport in the unsaturated zone typically requires solution of the nonlinear Richards equation and an advective-dispersive equation for contaminant transport as a function of time. Such solutions are possible but computationally expensive. A simplified water balance approach to solve fluid flow in shallow, drained unsaturated zones has been developed and refined over the last 15 years. The objectives of this study were to use results from a water balance model to obtain solutions for solute transport in drained, shallow water table soils, and to compare the results with solutions based upon Richards' equation. Transient soil water flux rates computed with a water balance model were used as input to a Petrov- Galerkin advective-dispersive transport model to simulate solute transport in unsaturated soils. The transport model was checked for consistency by comparison with an analytical solution. Sample simulations showed good agreement between a Richards' equation-based transport model and a water balance- based transport model. Simulations were performed to show predicted trends in water quality over 1-year periods. 164 NAL Call. No.: 292.8 W295 Modeling of carbon dioxide transport and production in soil. 1. Model development. Simunek, J.; Suarez, D.L. Washington, D.C. : American Geophysical Union; 1993 Feb. Water resources research v. 29 (2): p. 487-497; 1993 Feb. Includes references.

Language: English Descriptors: Carbon dioxide; Production; Transport processes; Spatial distribution; Water flow; Heat flow; Respiration; Soil biology; Soil chemistry; Prediction; Simulation models; Mathematical models Abstract: Knowledge of the CO2 concentration in the unsaturated zone is essential for prediction of solution chemistry in the vadose zone and groundwater recharge as well as for quantifying carbon source/sink terms as part of the global CO2 mass balance. In this paper we present a predictive simulation model, SOILCO2, based on process-oriented relationships. The model includes one-dimensional water flow and multiphase transport of CO2 utilizing the Richards and the convection-dispersion equations, respectively, as well as heat flow and a CO2 production model. The transport of CO2 in the unsaturated zone can occur in both the liquid and gas phases. The gas transport equation accounts for production of CO2 and uptake of CO2 by plant roots associated with root water uptake. The CO2 production model considers both microbial and root respiration which is dependent on water content, temperature, growth, salinity and plant and soil characteristics. Heat flow is included, since some gas transport parameters, partitioning coefficients and production parameters are strongly temperature dependent. The resulting set of partial differential equations is solved numerically using the finite element and finite difference methods. 165 NAL Call. No.: 292.8 W295 Modeling of carbon dioxide transport and production in soil. 2. Parameter selection, sensitivity analysis, and comparison of model predictions to field data. Suarez, D.L.; Simunek, J. Washington, D.C. : American Geophysical Union; 1993 Feb. Water resources research v. 29 (2): p. 499-513; 1993 Feb. Includes references. Language: English Descriptors: California; Missouri; Carbon dioxide; Production; Spatial distribution; Transport processes; Mathematical models; Simulation models; Prediction; Steady flow; Transient flow; Water flow; Heat flow; Triticum aestivum; Zea mays; Glycine max; Environmental factors Abstract: In paper 1 of this two-paper series (Simunek and Suarez, this issue) we presented a description of the numerical model, SOILCO2, for CO2 transport and production in the unsaturated zone. In paper 2 the model sensitivity to various parameters is evaluated by both steady state and transient simulations, with a range in the parameter values typically found under field conditions. We also select parameter values for optimal plant and microbial CO2 production and production dependence on temperature, water

content, osmotic potential and gas composition for plant and microbial respiration, all based on literature review. The predictive capabilities of the SOILCO2 model are evaluated by comparing model simulations to published field data from Missouri for three different crops and two growing seasons under transient conditions as well as a data set collected in Riverside, California, under relatively constant water content at depth. The model provided good prediction of the CO2 flux to the atmosphere as well as the concentrations in the root zone for all data sets. 166 NAL Call. No.: TD1.E2 no.91/039 Modeling of nonpoint source water quality in urban and non- urban areas. Donigian, Anthony S.; Huber, Wayne C. Environmental Research Laboratory (Athens, Ga.) Athens, Ga. : Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency,; 1991. vi, 72 p. : ill. (EPA/600/3 ; 91/039). June 1991. Includes bibliographical references. Language: English Descriptors: Water 167 NAL Call. No.: 290.9 AM32T Modeling pollutant transport in runoff and sediment. Ashraf, M.S.; Borah, D.K. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Nov. Transactions of the ASAE v. 35 (6): p. 1789-1797; 1992 Nov. Includes references. Language: English Descriptors: Agricultural chemicals; Cyanazine; Nitrates; Phosphates; Pollutants; Rain; Runoff; Sediment; Simulation models Abstract: A dynamic model was developed to simulate mixing of rainwater with soils containing agricultural nutrients and pesticides, entrainment of these pollutants to runoff, and their transport in runoff and sediment within a watershed and during a single storm event. The model is an advancement to the existing models in simulating chemical transport during individual storms. It routes infiltrating rainwater and solutes through the soil profile using concepts of complete mixing and piston displacement. When runoff begins, chemical exchange between runoff and a mixing soil layer of the soil profile, containing the chemicals in dissolved and adsorbed forms, are simulated using the concept of non-uniform mixing with respect to the soil layer depths. Entrained chemicals in runoff are routed along slope lengths in dissolved and adsorbed forms based on mass conservation. The basic model concepts and algorithms on chemical mixing and entrainment were tested for time varying concentrations of nitrate, phosphate, and cyanazine in runoff using a suitable laboratory

data set found in the literature. A total of 15 model runs, 5 for each pollutant, were made. Predicted concentrations were compared with the respective observed data. The comparisons showed that the concepts and the algorithms were valid and promising. 168 NAL Call. No.: QH540.J6 Modeling selenium transport in steady-state, unsaturated soil columns. Alemi, M.H.; Goldhamer, D.A.; Nielsen, D.R. Madison, Wis. : American Society of Agronomy; 1991 Jan. Journal of environmental quality v. 20 (1): p. 89-95; 1991 Jan. Includes references. Language: English Descriptors: Selenium; Soil air; Soil chemistry; Soil flora; Soil sterilization; Transport processes; Adsorption; Leaching; Methodology; Microbial activities; Simulation models Abstract: This study was conducted to characterize batch adsorption of selenate SeO4(2-), selenite (SeO4(2-), and selenomethionine (Se-CH2CH2CHNH2COOH)2 and transformations of Se in the presence of microbial activity in Panoche loam (fine-loamy, mixed, calcareous, thermic Typic Torriorthents). The effects of sterilization, enhanced microbial activity, and aerobic vs. anaerobic conditions on the transport of pulse-fed Se in soil columns were also investigated. Selenate was rapidly leached in the soil columns compared with selenomethionine and selenite both of which invaded the columns to only a limited extent. Adsorption was highest for selenite and least for selenate. Selenate was transformed to reduced and less mobile forms when soil was C-enriched, particularly with smaller water fluxes and under anaerobic conditions. Systems of partial differential equations (PDEs) involving equilibrium adsorption of Se are set up to simulate transport of selenate, selenite, and selenomethionine under sterilized conditions. The transport model is solved by an iterative procedure using a finite difference scheme. Experimentally determined adsorption parameters of selenite and selenomethionine did not produce a satisfactory fit when used in simulation of these Se species in column studies. The Se transport model adequately simulated Se concentrations in soil solution under sterilized conditions when the adsorption coefficients derived from batch experiments were adjusted. No transport modeling was considered for nonsterilized conditions. 169 NAL Call. No.: SB191.R5I59 Modeling soil processes with N dynamics as an example. Kirk, G.J.D.; Rachhpal-Singh Manila : The Institute; 1991 Nov. IRRI research paper series - International Rice Research Institute (151): p. 39-42; 1991 Nov. In the series analytic: Systems simulation at IRRI / edited by F.W.T. Penning de Vries, M.J. Kropff, P.S. Teng, and G.J.D. Kirk. Includes

references. Language: English Descriptors: Urea fertilizers; Prediction; Transport processes; Volatilization; Simulation models; Computer simulation; Losses from soil systems; Nitrogen; Rhizosphere 170 NAL Call. No.: 292.8 W295 Modeling solute transport influenced by multiprocess nonequilibrium and transformation reactions. Brusseau, M.L.; Jessup, R.E.; Rao, P.S.C. Washington, D.C. : American Geophysical Union; 1992 Jan. Water resources research v. 28 (1): p. 175-182; 1992 Jan. Includes references. Language: English Descriptors: Contaminants; Solutes; Transport processes; Sorption; Transformation; Degradation; Prediction; Simulation; Mathematical models Abstract: We present an advective-dispersive solute transport model that explicitly accounts for multiple sources of nonequilibrium and transformation reactions during steady state flow in porous media. The multiprocess nonequilibrium with transformation (MPNET) model is formulated for cases where nonequilibrium, caused by a combination of transport- related and sorption-related processes, and abiotic/biotic transformations can be described as first-order processes. The impact of the coupling of nonequilibrium and transformation reactions on solute transport is examined using selected illustrative examples. The performance of the model is evaluated by comparing predictions obtained with the model, where values for all model parameters are obtained independently, to a data set obtained from the literature. The prediction obtained with the MPNET model matched the data very well, much better than did the predictions obtained with the MPNET model assuming no degradation and with a model that does not account for rate-limited sorption. 171 NAL Call. No.: QH540.J6 Modeling the influence of sorption and transformation on pesticide leaching and persistence. Boesten, J.J.T.I.; Linden, A.M.A. van der Madison, Wis. : American Society of Agronomy; 1991 Apr. Journal of environmental quality v. 20 (2): p. 425-435; 1991 Apr. Includes references. Language: English Descriptors: Diuron; Aldicarb; Leaching; Persistence; Soil morphological features; Sandy soils; Mathematical models; Application date; Spring; Autumn; Continuous cropping; Zea mays; Water uptake; Water flow; Soil temperature;

Precipitation; Evapotranspiration Abstract: Pesticide leaching to ground water at 1 m depth and pesticide persistence in the plow layer were calculated with a mathematical model for a sandy soil continuously cropped with maize (Zea mays L.) and exposed to weather conditions in a temperate climate. The pesticide was applied in spring. In the model water flow was described by Darcy's law and water uptake by the crop was included. Daily averages of meteorological conditions (rainfall, evapotranspiration, soil temperature) were used as input. The model assumes first-order transformation, equilibrium sorption (Freundlich equation), and passive plant uptake. Pesticide leaching and persistence were calculated as a function of pesticide sorption (characterized by the organic-matter/water distribution coefficient, Kom) and of transformation rate. It was found that pesticide leaching is very sensitive to both Kom and the transformation rate: changing Kom or the transformation rate by a factor of 2 changes the fraction of the dose leached typically by about a factor of 10. Pesticide persistence in the plow layer was found to be sensitive to Kom at low transformation rates and sensitive to the transformation rate at high Kom values. Additional calculations showed that autumn application results in much higher leaching of nonsorbing pesticides with short half-lives than spring application (difference of two orders of magnitude). 172 NAL Call. No.: 292.8 W295 Modeling the nonequilibrium transport of linearly interacting solutes in porous media: a review. Sardin, M.; Schweich, D.; Leij, F.J.; Van Genuchten, M.T. Washington, D.C. : American Geophysical Union; 1991 Sep. Water resources research v. 27 (9): p. 2287-2307; 1991 Sep. Includes references. Language: English Descriptors: Transport processes; Solutes; Aggregates; Porosity; Soil pore system; Time; Dynamics; Kinetics; Mathematical models Abstract: The transport of linearly interacting solutes in porous media is investigated with the help of residence time distributions, transfer functions, methods of system dynamics, and time-moment analyses. The classical one-dimensional convection-dispersion equation is extended to two-region (mobile-immobile water) transport by including diffusional mass transfer limitations characteristic of aggregated soils. The two-region model is further revised by incorporating the effects of multiple retention sites (in parallel or in series), multiple porosity levels, and arbitrary but steady flow fields. It is shown that different physical situations can be represented by a relatively small number of transfer functions containing only two types of parameters: distribution coefficients to account for equilibrium properties and characteristic times reflecting kinetic

processes. Relevant kinetic processes include convective transport, hydrodynamic dispersion, adsorption-desorption, and physical or chemical mass transfer limitations. In most situations, theoretical breakthrough curves are found to be relatively insensitive to the mathematical structure of the transfer function, irrespective of the physical interpretation of the distribution coefficients and the characteristic times in the model. This means that alternative physical and chemical interpretations of model parameters can lead to nearly identical breakthrough curves. Certain transfer time distributions can lead to quite unusual shapes in the breakthrough curves; these curves strongly depend on the characteristic times and a few operational variables. Results of this study show that the transfer time distribution is an extremely useful tool for explaining some unexpected experimental results in the solute transport literature. 173 NAL Call. No.: 56.9 SO3 Modeling the transport and retention of cadmium in soils: multireaction and muticomponent approaches. Selim, H.M.; Buchter, B.; Hinz, C.; Ma, L. Madison, Wis. : The Society; 1992 Jul. Soil Science Society of America journal v. 56 (4): p. 1004-1015; 1992 Jul. Includes references. Language: English Descriptors: Soil types (genetic); Cadmium; Transport processes; Heavy metals; Retention; Kinetics; Mathematical models; Simulation models; Ion exchange; Sorption Abstract: A major challenge in modeling the mobility or solutes in soils is to take into account the time-dependent retention of reactive solutes in a transport model that can be evaluated by independent experiments. The kinetics of retention and transport or Cd in two soils were investigated in this study. Time-dependent batch experiments were carried out to describe the extent of Cd sorption by two soils. Miscible-displacement experiments were conducted to quantify Cd transport in soil columns that received single and multiple Cd pulses. A multi-reaction convective-dispersive transport model inadequately predicted effluent concentrations for both soils when independently measured parameters of retention- release rate coefficients were obtained from batch data sets. We developed a multicomponent approach that accounts for reversible and irreversible Cd retention during transport in soils. Retention mechanisms considered include instantaneous equilibrium ion exchange and a specific sorption process that was based on a second-order (Langmuir) kinetic reaction. The multicomponent model adequately predicted the observed breakthrough results. The use of kinetic ion exchange and specific sorption for irreversible retention provided improved overall predictions of the results. Parameter values used for the rates of specific sorption (kf) and that for kinetic ion exchange (alpha) which provided improved predictions for single-pulse applications, were similar to those used for

multiple-pulse applications. This finding was consistent for both soils and was considered to add credence to our multicomponent model. 174 NAL Call. No.: 30 AD9 Modeling the transport and retention of inorganics in soils. Selim, H.M. San Diego, Calif. : Academic Press; 1992. Advances in agronomy v. 47: p. 331-384; 1992. Literature review. Includes references. Language: English Descriptors: Soil chemistry; Solutes; Transport processes; Leaching; Movement in soil; Mathematical models; Literature reviews 175 NAL Call. No.: QH545.A1E58 Modelling pesticide movement in forested watersheds: use of PRZM for evaluating pesticide options in loblolly pine stand management. Dowd, J.F.; Bush, P.B.; Neary, D.G.; Taylor, J.W.; Berisford, Y.C. Tarrytown, N.Y. : Pergamon Press; 1993 Mar. Environmental toxicology and chemistry v. 12 (3): p. 429-439; 1993 Mar. Paper presented at the "Symposium on Pesticides in Forest Management, 11th Annual Meeting of the Society of Environmental Toxicology and Chemistry," November 11-15, 1990, Arlington, Virginia. Includes references. Language: English Descriptors: Georgia; Pesticides; Watersheds; Forests; Pinus taeda; Leaching; Profiles; Weather; Climatic factors; Soil water movement; Forest management; Simulation models; Prediction 176 NAL Call. No.: 292.8 J82 Modelling surface runoff contamination by soil chemicals under transient water infiltration. Wallach, R.; Shabtai, R. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Mar. Journal of hydrology v. 132 (1/4): p. 263-281; 1992 Mar. Includes references. Language: English Descriptors: Agricultural chemicals; Contamination; Soil water; Runoff; Overland flow; Rain; Solutes; Transport processes; Infiltration; Sloping land; Relationships; Prediction; Mathematical models Abstract: A model was developed to predict the potential contamination of overland flow by chemicals removed from soil water by rainfall on sloping soil. The model accounts for transient water infiltration, overland flow and convective-

dispersive solute transport in the soil. Solutes are assumed to be subjected to linear equilibrium sorption onto the soil's solid phase. Numerical simulations indicated that the value of the coefficient for soil chemical transfer to surface runoff does not affect the soil surface concentration when soil is initially dry, but is linearly related to the dissolved chemical flux to overland flow. This enables an approximate solution to the convective-dispersive equation for determining soil surface concentration, independent of its determination from rainfall-runoff relationships. Simulated dissolved chemical concentrations at the soil surface and in surface runoff were determined for different antecedent soil moistures and rainfall intensities. These concentrations were found to be lower when antecedent moisture was low, because ponding time for drier soils is longer and during this period soil solutes are therefore displaced downward by greater volumes of infiltrating water. For a specified initial soilwater content, higher rainfall rates cause higher dissolved chemical concentrations at the soil surface and in runoff water. The hydrological parameters (e.g. soil-surface slope, length and roughness) affecting the residence time of surface water on the field, greatly affect runoff concentration for a short time after the initiation of overland flow. The runoff concentration for longer periods is mainly affected by soil surface concentration, which is in turn controlled by the dispersion of the chemicals in the soil. The distribution coefficient between the liquid and solid phases of the soil controls the release of adsorbed chemicals to the soil solution and therefore affects the runoff concentration. 177 NAL Call. No.: 56.8 J823 Modelling water and solute transport in macroporous soil. I. Model description and sensitivity analysis. Jarvis, N.J.; Jansson, P.E.; Dik, P.E.; Messing, I. Oxford : Blackwell Scientific Publications; 1991 Mar. The Journal of soil science v. 42 (1): p. 59-70; 1991 Mar. Includes references. Language: English Descriptors: Soil physics; Macropore flow; Solutes; Macropores; Transport processes; Mathematical models; Diffusion models; Equations Abstract: A detailed mechanistic model of water movement and transport of non-reactive solute in a macroporous soil is described. One important feature of the model is that it may be run in either one or two flow domains using the same values for the hydraulic properties characterizing the soil. Water and solute movement in the micropores is calculated with the Richards and convection-dispersion equations and, in two domains, this is coupled to fluxes of water and solute in the macropores by empirical interaction terms. These interaction terms are redundant in the one-domain model, which simply reduces to the non-steady state convection-dispersion equation. A sensitivity analysis is presented showing how it

is possible to identify conditions under which a macropore flow domain may need to be considered. In part II (Jarvis et al., 1991), the model is evaluated under field conditions in chloride breakthrough experiments in soil monolith lysimeters. 178 NAL Call. No.: 56.8 J823 Modelling water and solute transport in macroporous soil. II. Chloride breakthrough under non-steady flow. Jarvis, N.J.; Bergstrom, L.; Dik, P.E. Oxford : Blackwell Scientific Publications; 1991 Mar. The Journal of soil science v. 42 (1): p. 71-81; 1991 Mar. Includes references. Language: English Descriptors: Soil physics; Macropore flow; Solutes; Chlorides; Leaching; Prediction; Topsoil; Hydraulic conductivity; Porosity; Clay soils; Mathematical models; Diffusion models Abstract: A model of water and solute transport in macroporous soils (Jarvis et al., 1991) has been evaluated in column breakthrough experiments under field conditions. Hydraulic properties were first measured in replicate soil monolith lysimeters sampled from grass ley and continuous barley treatments in a clay soil. A pulse input of 0.05 M KCl was then supplied by drip irrigation and measurements made of the water discharge and chloride leaching resulting from the natural rainfall over a 1-month period. The results showed that the macropores constituted the dominant flow pathway (accounting for 80% of the total water outflow) and that diffusive exchange of chloride between the two flow domains was the main factor causing variability in leaching. Larger hydraulic conductivities and macroporosities in the lower topsoil and at plough depth in the grass ley monoliths were taken as evidence of structural amelioration. Less of the applied chloride was leached in the grass monoliths than in the barley (means of 20% and 31% respectively). This was mainly due to a smaller effective aggregate size and thus a more efficient diffusion-controlled retention. 179 NAL Call. No.: 290.9 AM32T Modification of EPIC to incorporate drainage systems. Sabbagh, G.J.; Bengtson, R.L.; Fouss, J.L. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Mar. Transactions of the ASAE v. 34 (2): p. 467-472; 1991 Mar. Includes references. Language: English Descriptors: Louisiana; Drainage; Erosion; Evapotranspiration; Runoff; Simulation models; Water table; Watersheds; Zea mays; Crop production Abstract: EPIC-WT is a modified verison of the Erosion Productivity Impact Calculator (EPIC). It is capable of

determining the relationship between soil erosion and soil productivity, simulating the daily watertable fluctuations, and predicting the effect of subsurface drainage systems on the water budget components for shallow watertable soils. Validation of the performance of EPIC-WT in simulating surface and subsurface drained flows, daily watertable fluctuations, sediment loss, and crop yield was conducted over seven years (1981-1987) on a clay loam soil near Baton Rouge, LA. Satisfactory results were obtained. 180 NAL Call. No.: 290.9 AM32T Modification of Epic to simulate pesticide activities: EPIC- PST. Sabbagh, G.J.; Geleta, S.; Elliott, R.L.; Williams, J.R.; Griggs, R.H. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Jul. Transactions of the ASAE v. 34 (4): p. 1683-1692; 1991 Jul. Includes references. Language: English Descriptors: Georgia; Louisiana; Atrazine; Metolachlor; Groundwater; Leaching; Mathematical models; Runoff; Water pollution Abstract: The need for a mathematical model capable of simulating simultaneously the effects of different agricultural management practices on crop yield, and chemical (nutrients and pesticides) losses by surface runoff, sediment movement and leaching below the rootzone has prompted the development of EPIC-PST. This model was developed by using EPIC as a building block and adopting from the GLEAMS model the pesticide related subroutines. EPIC-PST was evaluated by a) validating the incorporation of GLEAMS pesticide subroutines into EPIC; b) comparing chemical losses by runoff and chemical concentration in the soil profile with observed data from Ben Hur Research Farm, near Baton Rouge, Louisiana; and c) comparing chemical concentration in the soil profile with observed data from Dorminey farm near Tifton, Georgia. It was concluded from the evaluation that the incorporation of GLEAMS pesticide-related subroutines was successfully accomplished. EPIC-PST overestimated total Atrazine loss in runoff by 7% and underestimated total Metolachlor loss in runoff by 8% when compared to the values observed at Ben Hur Research Farm. For both sites, comparison of observed and predicted pesticide concentrations in the soil profile has shown that the model is apparently simulating faster movement of chemical through the rootzone than that observed in the field. However, the patterns in the changes of chemical concentration with time were similar to the observed. 181 NAL Call. No.: S1.S68 Moisture transport in plastic coverings. Sariev, A.L.; Kotovich, I.N.; Kobylyanskii, G.V.; Shukurov, M.S. New York, N.Y. : Allerton Press; 1991. Soviet agricultural sciences (5): p. 53-57; 1991. Translated from: Vsesoiuznaia akademiia sel'skokhoziaistvennykh nauk.

Doklady, (5), p. 53-56. (20 AK1). Includes references. Language: English; Russian Descriptors: Greenhouses; Plastic cladding; Condensation; Runoff; Mathematical models; Equations 182 NAL Call. No.: 56.9 SO3 Moment method applied to solute transport with binary and ternary exchange. Leij, F.J.; Dane, J.H. Madison, Wis. : The Society; 1992 May. Soil Science Society of America journal v. 56 (3): p. 667-674; 1992 May. Includes references. Language: English Descriptors: Solutes; Movement in soil; Cation exchange; Transport processes; Mathematical models; Simulation models; Hydrodynamic dispersion Abstract: When modeling transport of exchanging solutes in soils, it is sometimes conveniently assumed that the solutes interact linearly with the solid phase of the soil. In this study, an attempt was made to quantify the influence of nonlinear cation exchange on solute spreading with the moment method. Theoretical expressions for the first four moments were derived based on the equilibrium and physical nonequilibrium models of the advection-dispersion equation (ADE). Displacement experiments were conducted in which either a NaCl pulse (binary exchange) or a pulse of KBr and NaBr (ternary exchange) was applied to a CaBr2-saturated medium. Values for the transport parameters were determined with moment analysis and curve fitting. The observed breakthrough curves were somewhat better reproduced with parameters obtained from curve fitting than from the moment method. However, the curve-fitting program produced some unrealistic parameter estimates for the nonequilibrium model. A disadvantage of the moment method was that the fourth-order moment sometimes yielded unstable results for the nonequilibrium model. Parameters form the anion displacement were used to estimate the theoretical variance due to hydrodynamic dispersion and nonequilibrium spreading for the cation breakthrough curves. The difference between the variance of the observed cation breakthrough curve and these theoretical variances was used as an approximation of the variance due to nonlinear exchange. Particularly for the ternary exchange, the variance due to nonlinear exchange was often several times greater than predicted according to the transport model. The results enabled us to quantify errors in dispersion coefficient (D) values directly determined from cation-displacement experiments. 183 NAL Call. No.: 290.9 AM3PS (IR) Movement of nonpoint-source contaminants through heterogeneous soils. Tracy, J.C.

New York, N.Y. : American Society of Civil Engineers; 1992 Jan. Journal of irrigation and drainage engineering v. 118 (1): p. 88-103; 1992 Jan. Includes references. Language: English Descriptors: U.S.A.; Groundwater; Groundwater pollution; Pollutants; Movement in soil; Transport processes; Seepage; Soil water content; Simulation; Probabilistic models; Deterministic models; Comparisons 184 NAL Call. No.: 56.8 AU7 Movement of solutes associated with intermittent soil water flow. I. Tritium and bromide. Scotter, D.R.; Tilman, R.W. East Melbourne : Commonwealth Scientific and Industrial Research Organization; 1991. Australian journal of soil research v. 29 (2): p. 175-183; 1991. Includes references. Language: English Descriptors: Silt loam soils; Potassium bromide; Tritiated water; Soil water movement; Solutes; Movement in soil; Leaching; Diffusion; Equations; Hydrodynamic dispersion; Diffusion models 185 NAL Call. No.: 292.9 AM34 Multicriterion analysis of groundwater contamination management. Shafike, N.G.; Duckstein, L.; Maddock, T. III Bethesda, Md. : American Water Resources Association; 1992 Jan. Water resources bulletin v. 28 (1): p. 33-43; 1992 Jan. Includes references. Language: English Descriptors: Groundwater pollution; Groundwater; Water management; Decision making; Water supply; Wastes; Costs; Mathematical models Abstract: Multicriterion decision making (MCDM) techniques were used to analyze a groundwater contamination management problem from the viewpoint of conflicting multiple objectives. The groundwater management model was used to find a compromise strategy for trading off fresh water supply, containment of the waste, and total pumping cost in a hypothetical confined aquifer affected by previous waste disposal action. A groundwater flow model was used to formulate the hydraulic constraints. A linear system model was used to describe drawdown and velocity as functions of the decision variables which were pumping rates. The model determines the pumping location and rates. A modified epsilon-constraint method was used to generate the set of nondominated solutions which were the alternative compromise strategies. Three different MCDM techniques, Compromise programming (CP), ELECTRA II and MCQA

II, were used to select a "satisficing" alternative. Analysis of the results showed that, although these techniques follow different principles, the same preferred strategies were reached. Also, it was noticed that maintaining high groundwater velocities is expensive and difficult. In order to meet a two year target date, large amounts of water had to be pumped. Therefore, rapid restoration results in large pumping volumes and high costs. 186 NAL Call. No.: HD1.A3 A multi-objective dynamic programming model for evaluation of agricultural management systems in Richmond County, Virginia. Zhu, M.; Taylor, D.B.; Sarin, S.C. Essex : Elsevier Applied Science Publishers; 1993. Agricultural systems v. 42 (1/2): p. 127-152; 1993. In the special issue: Application of dynamic optimization techniques to agricultural problems / edited by C.R. Taylor. Includes references. Language: English Descriptors: Virginia; Legumes; Farm management; Farming systems; Dynamic programming; Simulation models; Economic impact; Environmental impact; Nitrogen fertilizers 187 NAL Call. No.: 290.9 AM32T Multiobjective parameter estimation for hydrologic models-- multiobjective programming. Yan, J.; Haan, C.T. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 May. Transactions of the ASAE v. 34 (3): p. 848-856; 1991 May. Includes references. Language: English Descriptors: Oklahoma; Hydrology; Precipitation; Problem solving; Programming; Runoff; Simulation models; Watershed management Abstract: A procedure for parameter estimation in multipurpose hydrologic models based on multiobjective programming is developed. The procedure helps overcome a problem which often occurs using traditional parameter estimation techniques-producing parameters that are good with respect to one objective but poor in terms of other objectives. The proposed method was tested using a precipitation runoff modeling system. The multiobjective function used had three objectives for estimating four parameters. It is shown that substantial improvement in parameter estimates can be obtained using the tested method. 188 NAL Call. No.: QH540.N3 Multiphase contaminants in natural permeable media: various modeling approaches.

Corapcioglu, M.Y.; Panday, S. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p. 191-220; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Pollutants; Transport processes; Mathematical models; Equations; Organic compounds; Groundwater flow; Soil water movement 189 NAL Call. No.: HD101.S6 Multiproduct production choices and pesticide regulation in Georgia. McIntosh, C.S.; Williams, A.A. Experiment, Ga. : The Association; 1992 Jul. Southern journal of agricultural economics - Southern Agricultural Economics Association v. 24 (1): p. 135-144; 1992 Jul. Includes references. Language: English Descriptors: Georgia; Pesticides; Uses; Groundwater pollution; Regulations; Agricultural production; Supply response; Profit functions; Econometric models; Economic impact; Taxes Abstract: An increasing emphasis on surface and groundwater quality and food safety may result in some form of pesticide regulations. A restricted profit function model of Georgia agriculture is used to examine the short-run effects of 2 and 5 percent reductions in all pesticides. Point estimates of short-run impacts, along with their 90 percent confidence intervals are presented. 190 NAL Call. No.: SF85.A1R32 National rangeland hydrology study. Flanagan, M. Denver, Colo. : Society for Range Management; 1992 Aug. Rangelands v. 14 (4): p. 217-218; 1992 Aug. Language: English Descriptors: Nebraska; Texas; Kansas; Wyoming; Colorado; Rangelands; Watersheds; Water quality; Vegetation; Erosion; Runoff; Models; Databases; Data analysis; Hydrological data; Plant communities 191 NAL Call. No.: QH540.N3 Nitrate ground-water modeling for agricultural and other nonpoint sources. Kelly, W.E.; Curtis, B.; Adelman, D.

Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 30: p. 97-113; 1991. In the series analytic: Nitrate contamination: Exposure, consequence, and control / edited by I. Bogardi and R.D. Kuzelka. Proceedings of the NATO Advanced Research Workshop on Nitrate Contamination: Exposure, Consequences, and Control, September 9-14, 1990, Lincoln, Nebraska. Includes references. Language: English Descriptors: Nebraska; Nitrate; Nitrate fertilizers; Groundwater pollution; Groundwater recharge; Farmland; Simulation models 192 NAL Call. No.: QE1.E5 Nitrate pollution of groundwater in the Alsatian Plain (France)--a multidisciplinary study of an agricultural area: the Central Ried of the Ill River. Bernhard, C.; Carbiener, R.; Cloots, A.R.; Froehlicher, R.; Schenck, C.; Zilliox, L. New York, N.Y. : Springer; 1992 Sep. Environmental geology and water sciences v. 20 (2): p. 125-137; 1992 Sep. Includes references. Language: English Descriptors: France; Groundwater pollution; Nitrates; Maize; Grain crops; Intensive cropping; Hydromorphic soils; Problem solving; Grasslands; Geomorphology; Soil types; Agricultural development; Land use; Models 193 NAL Call. No.: 292.8 W295 Nitrate reduction in an unconfined sandy aquifer: water chemistry, reduction proceses, and geochemical modeling. Postma, D.; Boesen, C.; Kristiansen, H.; Larsen, F. Washington, D.C. : American Geophysical Union; 1991 Aug. Water resources research v. 27 (8): p. 2027-2045; 1991 Aug. Includes references. Language: English Descriptors: Nitrates; Soil pollution; Groundwater pollution; Aquifers; Arable land; Heathland; Coniferous forests; Land use; Transport processes; Reduction; Geochemistry; Models Abstract: Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate-contaminated groundwater emanate from the agricultural areas and spread through the aquifer. The aquifer can be subdivided into an upper 10- to 15-m thick oxic zone that contains O2 and NO3(-), and a lower anoxic zone characterized

by Fe2+-rich waters. The redox boundary is very sharp, which suggests that reduction processes of O2 and NO3(-) occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content of total dissolved ions in the NO3(-) free anoxic zone indicates the downward migration of contaminants and that active nitrate reduction is taking place. Nitrate is apparently reduced to N2 because both nitrite and ammonia are absent or found at very low concentrations. Possible electron donors in the reduced zone of the aquifer are organic matter, present as reworked brown coal fragments from the underlying Miocene. and small amounts of pyrite at an average concentration of 3.6 mmol/kg. Electron balances across the redoxcline, based on concentrations of O2, NO3(-), SO4(2-) and total inorganic carbon (TIC), indicate that pyrite is by far the dominant electron donor even though organic matter is much more abundant. Groundwater transport and chemical reactions were modeled using the code PHREEQM, which combines a chemical equilibrium model with a one- dimensional mixing cell transport model. Only the vertical component of the water transport was modeled since, in contrast to rates along flow lines, the vertical rates are close to constant as required by the one-dimensio 194 NAL Call. No.: 56.8 J822 Nitrogen leaching sensitivity to evapotranspiration and soil water storage estimates in EPIC. Benson, V.W.; Potter, K.N.; Bogusch, H.C.; Goss, D.; Williams, J.R. Ankeny, Iowa : Soil and Water Conservation Society of America; 1992 Jul. Journal of soil and water conservation v. 47 (4): p. 334-337; 1992 Jul. Includes references. Language: English Descriptors: U.S.A.; Water quality; Nitrogen; Leaching; Movement in soil; Percolation; Soil water balance; Evapotranspiration; Soil water; Storage; Estimation; Methodology; Comparisons; Simulation models; Climatic zones; Meteorological factors; Geographical distribution; Spatial variation; Soil variability; Crop growth stage; Crop management 195 NAL Call. No.: QH540.N3 Nitrogen modeling on a regional scale. Rijtema, P.E.; Kroes, J.G. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 30: p. 81-95; 1991. In the series analytic: Nitrate contamination: Exposure, consequence, and control / edited by I. Bogardi and R.D. Kuzelka. Proceedings of the NATO Advanced Research Workshop on Nitrate Contamination: Exposure, Consequences, and Control, September 9-14, 1990, Lincoln, Nebraska. Includes references.

Language: English Descriptors: Netherlands; Nitrate; Nitrate fertilizers; Water pollution; Groundwater pollution; Simulation models; Computer simulation; Runoff; Drainage; Farmland; Groundwater recharge 196 NAL Call. No.: TD419.R47 Nonpoint sources. Line, D.E.; Arnold, J.A.; Osmond, D.L.; Coffey, S.W.; Gale, J.A.; Spooner, J.; Jennings, G.D. Alexandria, Va. : The Federation; 1993 Jun. Water environment research v. 65 (4): p. 558-571; 1993 Jun. Literature review. Includes references. Language: English Descriptors: Agricultural production; Agricultural chemicals; Water pollution; Models 197 NAL Call. No.: TD419.R47 Nonpoint sources. Spooner, J.; Coffey, S.W.; Brichford, S.L.; Arnold, J.A.; Smolen, M.D.; Jennings, G.D.; Gale, J.A. Alexandria, Va. : The Federation; 1991 Jun. Research journal of the Water Pollution Control Federation v. 63 (4): p. 527-536; 1991 Jun. Literature review. Includes references. Language: English Descriptors: Water pollution; Groundwater; Surface water; Land use; Activity; Agricultural land; Forest soils; Urban areas; Economics; Planning; Water quality; Water resources; Models; Reviews 198 NAL Call. No.: QH540.N3 Numerical modeling of contaminant transport in groundwater. Gambolati, G.; Paniconi, C.; Putti, M. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p. 381-410; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Groundwater pollution; Pollutants; Transport processes; Groundwater flow; Soil water movement; Equations; Mathematical models

199 NAL Call. No.: 292.8 J82 Numerical simulation of infiltration and solute transport in an S-shaped model basin by a boundary-fitted grid system. Kinouchi, T.; Kanda, M.; Hino, M. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Jan. Journal of hydrology v. 122 (1/4): p. 373-406; 1991 Jan. Includes references. Language: English Descriptors: Subsurface layers; Soil water movement; Solutes; Transport processes; Rain; Simulation; Water; Discharge; Water distribution; Velocity; Unsaturated flow; Capillary fringe; Overland flow; Runoff; Groundwater; Mathematical models; Simulation models Abstract: The boundary-fitted grid method, which transforms a complicated computational domain into a rectangular domain, is applied for the moisture and solute transport problems in the unsaturated soil layer of an S-shaped model hillslope. In the transformed domain, the fundamental equations of moisture and solute transport (i.e. the Richards equation and the Fickian equation) can be easily discretized into the finite-difference form. For three types of rainfall pattern (a unit rainfall, two-unit successive rainfalls and two unit rainfalls with a lag between them), hydrographs of total (pre-event and event water) and event water discharges, contour lines of soil moisture, pressure and total hydraulic head distributions, and flow velocity vectors are compared. For a relatively thick soil layer or for a relatively light rainfall, the capillary fringe effect plays an important role, whereas for a relatively thin soil layer or for a relatively heavy rainfall, overland flow from a variable source area is superimposed on the capillary-fringe-type runoff. 200 NAL Call. No.: 10 J822 Nutrient cycling and losses based on a mass-balance model in grazed pastures receiving long-term superphosphate applications in New Zealand. 1. Phosphorus. Nguyen, M.L.; Goh, K.M. Cambridge : Cambridge University Press; 1992 Aug. The Journal of agricultural science v. 119 (pt.1): p. 89-106; 1992 Aug. Literature review. Includes references. Language: English Descriptors: New Zealand; Pastures; Phosphorus; Superphosphates; Cycling; Leaching; Grazing effects; Nutrient intake; Sheep; Simulation models; Literature reviews 201 NAL Call. No.: 10 J822 Nutrient cycling and losses based on a mass-balance model in grazed pastures receiving long-term superphosphate applications in New Zealand. 2. Sulphur. Nguyen, M.L.; Goh, K.M.

Cambridge : Cambridge University Press; 1992 Aug. The Journal of agricultural science v. 119 (pt.1): p. 107-122; 1992 Aug. Literature review. Includes references. Language: English Descriptors: New Zealand; Pastures; Fertilizer requirement determination; Sulfur; Superphosphates; Cycling; Grazing effects; Irrigated conditions; Leaching; Nutrient intake; Sheep; Simulation models; Literature reviews 202 NAL Call. No.: 26 T754 Nutrient leaching loss from two contrasting cropping systems in the humid tropics. Seyfried, M.S.; Rao, P.S.C. Guildford : Butterworth Scientific; 1991 Jan. Tropical agriculture v. 68 (1): p. 9-18; 1991 Jan. Includes references. Language: English Descriptors: Costa Rica; Cropping systems; Fertilizers; Leaching; Losses from soil systems; Nutrients; Soil fertility; Soil water balance; Simulation models; Humid tropics 203 NAL Call. No.: TD426.J68 One-dimensional immiscible displacement experiments. Thomson, N.R.; Graham, D.N.; Farquhar, G.J. Amsterdam : Elsevier; 1992 Aug. Journal of contaminant hydrology v. 10 (3): p. 197-223; 1992 Aug. Includes references. Language: English Descriptors: Soil pollution; Immiscible displacement; Prediction; Models; Groundwater pollution; Water table 204 NAL Call. No.: 292.8 J82 One-dimensional solute transport modelling in aggregated porous media. 1. Model description and numerical solution. Lafolie, F.; Hayot, C. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 Mar01. Journal of hydrology v. 143 (1/2): p. 63-83; 1993 Mar01. Special Issue: Modelling Flow and Transport in the Unsaturated Zone: Scale Problems and Spatial Variability. Includes references. Language: English Descriptors: Aggregates; Porosity; Macropores; Transport processes; Particle size distribution; Simulation models Abstract: A model for the simulation of solute transport in aggregated porous media is presented. Transport by convection

and dispersion in the mobile phase, diffusion of solute inside aggregates of arbitrary shapes and sizes, external mass transfer resistance and linear adsorption are considered. Depth-dependent properties of porous media and size distribution of aggregates are accounted for. The problem of solute diffusion inside arbitrarily shaped aggregates is rigorously and easily treated by application of the Laplace transformation and by introduction of an 'aggregate shape function'. The whole system of equations is solved by: (1) application of the Laplace transformation; (2) introduction of the 'aggregate shape function' to reduce the transport problem to a single ordinary differential equation whatever the geometry of aggregates and the phenomena accounted for (kinetic or instantaneous adsorption, external mass transfer resistance); (3) finite-difference numerical solution of this differential equation; (4) numerical inversion of the solution obtained in the Laplace space. The main advantages of this model are: (1) it incorporates, in a unique frame, the whole variety of models so far proposed for transport modelling in aggregated porous media (zero-, first- and higher order approaches); (2) it simplifies the numerical treatment so that there is no need to make simplifying assumptions about the phenomena; (3) it provides an accurate solution using very little computer time. The model is compared with previous solutions, analytical or numerical, obtained for simple aggregate geometries. 205 NAL Call. No.: 292.8 J82 One-dimensional solute transport modelling in aggregated porous media. 2. Effects of aggregate size distribution. Hayot, C.; Lafolie, F. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 Mar01. Journal of hydrology v. 143 (1/2): p. 85-107; 1993 Mar01. Special Issue: Modelling Flow and Transport in the Unsaturated Zone: Scale Problems and Spatial Variability. Includes references. Language: English Descriptors: Aggregates; Porosity; Particle size distribution; Particle velocity; Transport processes; Diffusion; Mathematical models Abstract: The influence of various aggregate size distributions on solute transport is analysed from a quantitative and qualitative point of view. Uniform, normal, log-normal and discrete aggregate size distributions are considered. The model described in Part 1 is used to calculate the breakthrough curves. The second-order moments and the sum of squared differences are used to compare the responses calculated with the distributions and with the mean radius. The influence of a distribution depends on the velocity, and consequently on the proportion of aggregates in situations of local equilibrium or physical non-equilibrium. Breakthrough curves calculated from normal distributions, whatever their spread, do not differ significantly from those calculated

using the mean radii, while slightly skewed narrow distributions generate significant differences. Thus, the skewness and not only the spreading of the distribution seem to modify the spreading of solute. The problem of using a unique 'mean radius' instead of a distribution is also considered. It is shown that the problem does not have a simple answer. For a given distribution, the existence of an acceptable mean radius depends strongly on the contrast between the mobile phase residence time and the distribution of characteristic diffusion times. Also, intuitively, acceptable mean radii are more easily found for narrow distributions. In most cases, it appears that a mean radius cannot be used instead of the distribution. The analysis of the way the distributions modify the breakthrough curves suggests that simple bimodal distributions presenting fast- and slow-reacting sites could be used in lieu of complete distributions. 206 NAL Call. No.: 280.8 J822 The on-farm costs of reducing groundwater pollution. Johnson, S.L.; Adams, R.M.; Perry, G.M. Ames, Iowa : American Agricultural Economics Association; 1991 Nov. American journal of agricultural economics v. 73 (4): p. 1063-1073; 1991 Nov. Includes references. Language: English Descriptors: Oregon; Groundwater pollution; Nitrates; Economic impact; Farm management; Crop yield; Simulation models; Farm income; Costs; Farm inputs; Taxes; Dynamic models Abstract: Agricultural chemicals are a source of groundwater pollution in some areas. Regulatory options to reduce such nonpoint pollution imply costs to producers. By integrating plant simulation, hydrologic, and economic models of farm- level processes, this study evaluates on-farm costs of strategies to reduce nitrate groundwater pollution. The empirical focus is on intensively managed, irrigated farms in the Columbia Basin of Oregon. Results suggest that changes in timing and application rates of nitrogen and water reduce nitrate pollution with little loss in profits. Once such practices are adopted, further reductions in nitrates can be achieved only at increasing costs to producers. 207 NAL Call. No.: 292.8 W295 Optimal data acquisition strategy for the development of a transport model for groundwater remediation. Tucciarelli, T.; Pinder, G. Washington, D.C. : American Geophysical Union; 1991 Apr. Water resources research v. 27 (4): p. 577-588; 1991 Apr. Includes references. Language: English Descriptors: Groundwater; Water quality; Water management;

Costs; Measurement; Stochastic models; Simulation models Abstract: The reliability of groundwater quality management algorithms is limited in large part by the uncertainty present in the model parameters. Because the field parameter measurement costs and the remediation costs must be supplied by the same financial source, the classical optimization procedure does not minimize the real total remediation investment. This research presents an algorithm able to find the total minimum for the sum of both the measurement and the pumping costs. A chance-constrained technique is used to cast the optimization problem in stochastic form, relating the concentration covariance matrix to the log-transmissivity covariance matrix by means of the transport equations and a first-order approximation for the uncertainty. The simulation model solves the steady state flow equations on a finite element triangular mesh and the transport equations using the backward method of characteristics. The resulting nonlinearly constrained optimization problem is solved using the quasi- linearity algorithm; this algorithm is designed to find a good initial point for the local minimum search when the feasible domain is not convex. 208 NAL Call. No.: aS21.R44A7 Opus: an integrated simulation model for transport of nonpoint-source pollutants at the field scale: volume I. Documentation. Smith, R.E. Beltsville, Md. : The Service; 1992 Jul. ARS - U.S. Department of Agriculture, Agricultural Research Service (98): 135 p.; 1992 Jul. Includes references. Language: English Descriptors: Pollution; Pollutants; Transport processes; Movement in soil; Hydrology; Computer simulation; Simulation models; Water flow; Meteorological factors; Growth models 209 NAL Call. No.: 292.8 W295 A partial contributing area model for linking rainfall simulation data with hydrographs of a small arid watershed. Ben-Asher, J.; Humborg, G. Washington, D.C. : American Geophysical Union; 1992 Aug. Water resources research v. 28 (8): p. 2041-2047; 1992 Aug. Includes references. Language: English Descriptors: Mali; Watersheds; Runoff water; Rain; Water harvesting; Measurement; Prediction; Simulation; Satellite imagery; Remote sensing; Catchment hydrology; Semiarid zones Abstract: Four years of runoff measurement (29 events) in Kangussano, Mali, were analyzed on the basis of the partial area contribution concept. The study region is semiarid and

the use of runoff water to satisfy crop consumption is of high importance. A first-order basin which included two flow channels draining an area of 1.14 X 10(6) ha (1.14 km(2)) was used for this purpose. The objective of this study was to develop and test a conceptual model to predict runoff on natural catchments of about this size. The model assumes that a basin is composed of a large number of pixels (satellite picture elements). Each pixel covers an area of 900 m(2). The hydraulic properties of a representative pixel are determined by runoff simulation experiments. The model calculates the number of runoff generating pixels at a given time and rain depth. The areal runoff is a product of these two factors. Analysis of satellite images from LANDSAT and SPOT indicated similarities of soil cover complexes between the study area and an experimental area in Upper Volta. Results of runoff simulation from this area were adapted for the study area and used for the calculations. A good agreement between predicted and measured contributing area was obtained when the number of runoff generating pixels was 80 pixels/mm effective rain. Predicted and measured hydrographs were also in good agreement. It was therefore concluded that the model can satisfactorily predict actual hydrographs from data generated by rainfall-runoff simulators. Dividing the watershed to surface elements of pixel's size makes the model capable of linking remote sensing information with simulation data in order to predict areal runoff. 210 NAL Call. No.: 292.8 W295 Partitioning solute transport between infiltration and overland flow under rainfall. Havis, R.N.; Smith, R.E.; Adrian, D.D. Washington, D.C. : American Geophysical Union; 1992 Oct. Water resources research v. 28 (10): p. 2569-2580; 1992 Oct. Includes references. Language: English Descriptors: Pollutants; Solutes; Transport processes; Infiltration; Overland flow; Rain; Surface water; Soil depth; Interactions; Mathematical models; Field experimentation Abstract: Solute transport from soil to overland flow is an important source of nonpoint pollution and was investigated through tracer studies in the laboratory and at an outdoor laboratory catchment. The depth of surface water interaction with soil, defined as the mixing zone is a useful value for approximate estimation of potential solute transport into surface water under rainfall. It was measured in the laboratory for a noninfiltration case (0.90 to 1.0 cm) and estimated through mass balance modeling for an infiltration case (0.52 and 0.73 cm). At an outdoor laboratory catchment, mixing zones were calculated through calibration of a numerical model that describes unsteady, uniform, infiltration and chemical transport. Overland flow was simulated using kinematic wave theory. Mixing zone depths ranged from 0.47 to 1.02 cm and were a linear function of rainfall intensity.

Also, the fraction of solute present in the mixing zone at the time of ponding which was extracted into overland flow was a linear function of the initial soil moisture content. A steady state analytical approximation of the solute transport model was also developed which overpredicted solute transport into overland flow by 1 to 60%. 211 NAL Call. No.: 290.9 AM32T PATS: pesticide availability and transfer simualtor. Kenimer, A.L.; Mitchell, J.K.; Bode, L.E. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 May. Transactions of the ASAE v. 35 (3): p. 841-853; 1992 May. Includes references. Language: English Descriptors: Alachlor; Terbufos; Pesticides; Absorption; Availability; Computer software; Losses from soil systems; Runoff; Simulation models Abstract: A computer model was developed to simulate the availability of pesticides in the soil matrix and uptake of these pesticides into overland flow. The Pesticide Availability and Transfer Simulator, PATS, accounts for the distribution of chemical within soil, adsorption kinetics, and chemical release from soil to overland flow. PLIERS, Pesticide Losses In Erosion and Runoff Simulator, was used to simulate surface transport of pesticides. Hydrologic data required by PATS and PLIERS were generated by the distributed parameter hydrologic model ANSWERS. PLIERS was enhanced through the incorporation of PATS. Performance of enhanced model was evaluated by comparing model predictions to observed data. PATS-enhanced PLIERS dissolved pesticide loss predictions were similar to predictions made with PLIERS alone and were in reasonably good agreement with observed data. PATS-enhanced PLIERS adsorbed pesticide loss predictions were frequently lower than observed losses, but were generally closer to observed losses than were PLIERS adsorbed pesticide loss predictions. 212 NAL Call. No.: 100 SO82 (3) Pesticide, nutrient and salt movement through the root zone. Carlson, C.G. Brookings, S.D. : The Station; 1991. TB - Agricultural Experiment Station, South Dakota State University (97): 6 p. (soil PR 90-41); 1991. Includes references. Language: English Descriptors: South Dakota; Pesticides; Nutrients; Root zone flux; Groundwater pollution; Models 213 NAL Call. No.: SB610.W39

Pesticide runoff simulations: long-term annual means vs. event extremes?. Leonard, R.A.; Truman, C.C.; Knisel, W.G.; Davis, F.M. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 725-730; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Simulation models; Pesticides; Runoff; Losses from soil; Rain; Simulation 214 NAL Call. No.: QD241.T6 Pesticide transport modelling in soil for risk assessment of groundwater contamination. Matthies, M.; Behrendt, H. London : Gordon and Breach Science Publishers; 1991. Toxicological and environmental chemistry v. 31/32: p. 357-365; 1991. Includes references. Language: English Descriptors: 2,4,5-t; Pesticide residues; Movement in soil; Soil water movement; Groundwater pollution Abstract: The risk of groundwater contamination with pesticides applied to soil surface depends on the soil properties, the agricultural practices, the climatic influences, and on the properties of the pesticides themselves. The EXSOL model was developed for the simulation of the transport and fate of pesticides and organic in soils. The dynamics of mobility, accumulation and degradation can be studied under various soil and climatic conditions. Transient water flow is provided from a simulation model of the field water balance. The percentages of the herbicide 2,4-5- trichlorophenoxyacetic acid in a luvisol soil after a single application in summer are compared with model calculations using sorption coefficients from laboratory column studies. The calculated percentages lie within the measured range, except for those in the deeper soil layer. The underestimation can be explained with preferential flow in macropores which may have occurred during the heavy rainfall six days after application. 215 NAL Call. No.: HD1773.A2N6 Physical and economic model integration for measurement of the environmental impacts of agricultural chemical use. Antle, J.M.; Capalbo, S.M. Morgantown, W.Va. : The Northeastern Agricultural and Resource Economics Association; 1991 Apr. Northeastern journal of agricultural and resource economics v. 20 (1): p. 68-82; 1991 Apr. Paper submitted in response to

call for papers on the theme "The Effects of Agricultural Production on Environmental Quality.". Includes references. Language: English Descriptors: Groundwater; Surface water; Water quality; Agricultural chemicals; Usage; Environmental impact; Measurement; Agricultural production; Cost benefit analysis; Models 216 NAL Call. No.: S601.A34 Potential contribution of ploughed grassland to nitrate leaching. Whitmore, A.P.; Bradbury, N.J.; Johnson, P.A. Amsterdam : Elsevier; 1992 Apr. Agriculture, ecosystems and environment v. 39 (3/4): p. 221-233; 1992 Apr. Includes references. Language: English Descriptors: England; Wales; Leaching; Nitrate nitrogen; Nitrogen; Plowing; Grassland soils; Soil organic matter; Losses from soil systems; Runoff water; Drinking water; Mathematical models 217 NAL Call. No.: QD1.A45 Potential leaching of herbicides applied to golf course greens. Smith, A.E.; Tillotson, W.R. Washington, D.C. : The Society; 1993. ACS Symposium series - American Chemical Society (522): p. 168-181; 1993. In the series analytic: Pesticides in urban environments: Fate and significance / edited by K.D. Racke and A.R. Leslie. Paper presented at the 203rd National Meeting of the American Chemical Society, April 5-10, 1992, San Francisco, California. Includes references. Language: English Descriptors: 2,4-d; Herbicide residues; Leaching; Golf courses; Golf green soils; Cynodon dactylon; Mathematical models; Simulation models Abstract: A critical issue facing the turfgrass industry is the environmental fate and safety of pesticides used in the management of national facilities. The purpose of our research program was to develop a data base for the determination of the potential movement of pesticides from golf course greens into potable aquifers. Lysimeters were developed, in the greenhouse, for the measurement of herbicide leaching from simulated greens. Data were obtained from lysimeters containing 'Tifdwarf' bermudagrass maintained as simulated greens and receiving treatments of the dimethylamine salt of 2,4-D as a split application at rates of 0.56 + 0.56 kg ae ha-1 on a two week interval. Only minute quantities of 2,4-D were detected in the effluent from the lysimeters containing two mixtures of rooting media. These data were compared to the

estimated values obtained from the GLEAMS mathematical model simulations using parameters independently determined to describe the lysimeter system. The GLEAMS model overestimated the actual data-values received from the lysimeter experiments on the potential for 2,4-D to leach through both rooting-media profiles. 218 NAL Call. No.: TC401.W27 The potential of runoff-farming in the Sahel region: developing a methodology to identifiy suitable areas. Tauer, W.; Prinz, D.; Vogtle, T. Hingham, Mass. : Kluwer Academic Publishers; 1991. Water resources management v. 5 (3/4): p. 281-287; 1991. Includes references. Language: English Descriptors: West Africa; Runoff farming; Runoff irrigation; Site selection; Crops; Water requirements; Soil; Water storage; Capacity; Models 219 NAL Call. No.: 290.9 AM32T Potential runoff quality effects of poultry manure slurry applied to fescue plots. Edwards, D.R.; Daniel, T.C. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Nov. Transactions of the ASAE v. 35 (6): p. 1827-1832; 1992 Nov. Includes references. Language: English Descriptors: Arkansas; Poultry manure; Runoff; Soil amendments; Water quality; Simulation models Abstract: A 3 X 2 factorial experiment was conducted to determine how quality of runoff from grassed areas amended with poultry manure slurry is affected by slurry application rate and rainfall intensity for storms occurring one day following application. Poultry manure slurry was applied at rates of 0, 220, and 879 kg N ha-1 to plots established with fescue grass on a Captina silt loam soil. Simulated rainfall was applied 24 h following slurry application at intensities of 5 and 10 cm h-1 until runoff had occurred for a duration of 0.5 h. Flow-weighted composite runoff samples were collected and analyzed for total Kjeldahl N, ammonia N, nitrate N, total P, dissolved reactive P, chemical oxygen demand, total suspended solids, and electrical conductivity. Effects of the experimental variables on both runoff concentrations and mass losses of slurry constituents were assessed by analyses of variance. Increasing slurry application rate significantly increased runoff concentrations of all slurry constituents investigated except nitrate N. For the affected slurry constituents, the relationships between runoff concentration of the constituent and slurry application rate appeared to be linear over the range of application rates used. Mass losses

of all slurry constituents except nitrate N significantly increased with increases in both slurry application rate and rainfall intensity. Relationships between mass losses and slurry application rate also appeared to be linear for the range of application rates used in the study. 220 NAL Call. No.: 290.9 AM3PS (IR) Precipitation distributions and Green-Ampt runoff. Van Mullem, J.A. New York, N.Y. : American Society of Civil Engineers; 1991 Nov. Journal of irrigation and drainage engineering v. 117 (6): p. 944-959; 1991 Nov. Includes references. Language: English Descriptors: Montana; Drainage; Runoff; Water distribution; Precipitation; Storms; Flow; Green and ampt equation; Infiltration; Prediction; Models 221 NAL Call. No.: 56.9 SO3 Predicting cation mobility in kaolinitic media based on exchange selectivities of kaolinite. Gaston, L.A.; Selim, H.M. Madison, Wis. : The Society; 1991 Sep. Soil Science Society of America journal v. 55 (5): p. 1255-1261; 1991 Sep. Includes references. Language: English Descriptors: Louisiana; Hapludults; Kaolinite; Sand; Subsoil; Cation exchange; Cation exchange capacity; Exchangeable cations; Calcium; Magnesium; Exchangeable sodium; Spatial distribution; Movement in soil; Transport processes; Mathematical models; Adsorption; Soil solution; Soil water; Potassium; Pores; Physicochemical properties; Prediction Abstract: Predictive modeling of cation transport in soils requires knowledge of the distribution of exchangeable species between solution and adsorbed phases. Such distribution of exchangeable species may be described with an exchange selectivity coefficient. Typically, the selectivity coefficient for any cation-exchange pair varies among soils. If the exchange complex of a soil is dominated by one type of exchanger, however, then the selectivity coefficient for that soil may be similar in magnitude to that for the principal mineral (or organic) constituent. Therefore, reasonably accurate predictions of cation transport in that soil might be obtained using exchange data for the dominant exchange material. This study was undertaken to determine whether exchange data for kaolinite could be successfully used in predicting Ca, Mg, and Na retention during movement in a Mahan series soil (clayey, kaolinitic, thermic Typic Hapludult). Binary-exchange isotherms for Ca-Mg, Ca-Na, and Mg-Na were generated for Ga-1 kaotinite (well crystallized). Selectivity coefficients derived from these data were used to describe

cation exchange during miscible displacement through columns of (i) kaolinite admixed with acid-washed sand and (ii) Mahan soil. Use of the selectivity coefficients for kaotinite provided good predictions of cation transport in the kaolinite/sand mixture. Predictions for the kaolinitic Mahan soil were not as good. The presence of small amounts of 2:1 minerals may have influenced the overall exchange behavior of the Mahan soil. When the uncertainty in values for selectivity coefficients and other exchange or transport parameters was considered, however, the exchange selectivity data for kaolinite could adequately describe cation transport in the Mahan soil. 222 NAL Call. No.: 56.8 AU7 Predicting exchangeable cation distributions in soil by using exchange coefficients and solution activity ratios. Phillips, I.R.; Black, A.S. East Melbourne : Commonwealth Scientific and Industrial Research Organization; 1991. Australian journal of soil research v. 29 (3): p. 403-414; 1991. Includes references. Language: English Descriptors: Exchangeable cations; Potassium; Magnesium; Movement in soil; Distribution; Leaching; Prediction; Models; Equilibrium; Soil solution; Soil water content 223 NAL Call. No.: 290.9 AM32T Predicting runoff of water, sediment, and nutrients from a New Zealand grazed pasture using CREAMS. Cooper, A.B.; Smith, C.M.; Bottcher, A.B. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Jan. Transactions of the ASAE v. 35 (1): p. 105-112; 1992 Jan. Includes references. Language: English Descriptors: New Zealand; Grassland management; Grazing effects; Hydraulic conductivity; Losses from soil systems; Prediction; Runoff; Water quality; Computers; Simulation models Abstract: The ability of the CREAMS model to predict loadings of runoff, sediment and nutrients from a New Zealand grazed pasture was evaluated. Before use, CREAMS was adapted to better represent N and P cycling in grazed pastures and the seasonal variation in hydraulic conductivity observed at the site. There was a moderately strong relationship (r2 = 0.81) between daily surface runoff volumes predicted by this modified model and volumes measured at the site for 62 events over a three and one half year period. Although the ability of the model to predict daily losses of sediment and nutrients was considerably less (r2 < 0.45), the model was always an unbiased predictor. This unbiased predictive ability provides

good estimates of losses over longer time scales (e.g., seasonal) which is often sufficient when evaluating the impacts of land use practices on water quality. The adapted CREAMS model successfully simulated measured reductions in edge-of-field losses of sediment and nutrient upon installation of a vegetated filter strip. We conclude that although CREAMS has limitations in representing the dynamics of grazed pastures, it shows potential as a water quality management tool in pastoral watersheds. 224 NAL Call. No.: QH545.A1E52 Predicting stream-water quality using catchment and soil chemical characteristics. Billett, M.F.; Cresser, M.S. Essex : Elsevier Applied Science; 1992. Environmental pollution v. 77 (2/3): p. 263-268; 1992. In the special issue: Effects of acidic pollutants on the chemistry of freshwater streams and lakes / edited by R. Harriman. Paper presented at the "Fourth International Conference on Acidic Deposition: Its Nature and Impacts," September 16-21, 1990, Glasgow, Scotland. Includes references. Language: English Descriptors: Northern scotland; Eastern scotland; Soil chemistry; Cation exchange; Prediction; Water quality; Hydrogen ions; Acidity; Calcium ions; Streams; Watersheds; Horizons; Simulation; Simulation models 225 NAL Call. No.: 292.8 W295 Prediction uncertainty in solute flux through heterogeneous soil. Destouni, G. Washington, D.C. : American Geophysical Union; 1992 Mar. Water resources research v. 28 (3): p. 793-801; 1992 Mar. Includes references. Language: English Descriptors: Solutes; Transport processes; Unsaturated flow; Degradation; Surface layers; Soil depth; Hydraulic conductivity; Soil zonation; Mathematical models Abstract: The Lagrangian framework presented by Dagan et al. (1992a) is used to analyze the uncertainty in predictions of the field scale mass flux of solute through the unsaturated zone. Transport of both nonreactive and degradable solutes is investigated for input sources that are located at the soil surface of fields with spatially variable hydraulic conductivity at saturation. The variances of the solute flux and accumulated mass, which quantify the corresponding prediction uncertainties, are illustrated at an arbitrary depth below the soil surface for different sizes and shapes of the input domain, and for different flow and degradation conditions. The greatest solute flux variances arise when the expected breakthrough curve has a steep slope. The coefficient

of variation for the solute flux is minimum at the peak arrival time of the expected breakthrough curve; this minimum value is relatively insensitive to the assumed distribution for solute travel time and to the loss rate coefficient for degradable solute. The prediction uncertainty decreases with increasing size of the input domain and is smaller for a planar source than for a linear one. The relative uncertainty in the total leached mass of degradable solute increases with increasing loss rate coefficient. 226 NAL Call. No.: 290.9 AM32T Predictive capabilities of erosion models for different storm sizes. Bingner, R.L.; Mutchler, C.K.; Murphree, C.E. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 Mar. Transactions of the ASAE v. 35 (2): p. 505-513; 1992 Mar. Includes references. Language: English Descriptors: Mississippi; Erosion; Rain; Runoff; Sediment yield; Simulation models; Slopes; Storms; Watersheds Abstract: When conservation practices are evaluated for erosion control effectiveness, the erosion or sediment yield produced by all the various storms that occur throughout the year should he considered. The Universal Soil Loss Equation neglects storms less than 13 mm unless the storm includes excessive rainfall intensities. Other erosion models have been developed that can easily consider all sizes of storms. This study evaluates the capability of several erosion models (CREAMS, SWRRB, EPIC, ANSWERS, and AGNPS) to predict runoff and erosion from rainfall events of 0 to 13, 13 to 25, 25 to 50, 50 to 75, and greater than 75 mm. Runoff and erosion were simulated on three watersheds in Mississippi: a sloping upland watershed, a flatland watershed, and a terraced watershed with underground outlets. Results show that the models predicted a linear relation of runoff and erosion with rainfall. However, the slope of the model regressions varied widely from data values. Only CREAMS and SWRRB were successful in predicting annual average runoff and sediment yield within 20% of measured amounts from the upland watershed and only SWRRB and AGNPS were successful in prediction for the flatland watershed. None of the models predicted within 20% of measured amounts from the terraced watershed. In all cases, errors were greatest for the larger storms. 227 NAL Call. No.: GB701.W375 no.92-4108 Preliminary results of the simulation of Oregon coastal basins using Precipitation-Runoff Modeling System (PRMS). Allen, Roderick L.; Laenen, Antonius United States, Bureau of Land Management, Geological Survey (U.S.) Portland, Or. : U.S. Dept. of the Interior, U.S. Geological Survey ; Denver, CO : Books and Open-File Reports Section [distributor],; 1993; I 19.42/4:92-4108. vi, 99 p. : ill., maps ; 28 cm. (Water-resources

investigations report ; 92-4108). Shipping list no.: 93-0315- P. Includes bibliographical references (p. 43-44). Language: English; English Descriptors: Hydrologic models; Runoff; Coasts 228 NAL Call. No.: 60.18 J82 Rangeland experiments to parameterize the water erosion prediction project model: vegetation canopy cover effects. Simanton, J.R.; Weltz, M.A.; Larsen, H.D. Denver, Colo. : Society for Range Management; 1991 May. Journal of range management v. 44 (3): p. 276-282; 1991 May. Includes references. Language: English Descriptors: Rangelands; Water erosion; Prediction; Simulation models; Rain; Interception; Canopy; Ground vegetation; Infiltration; Runoff; Losses from soil systems; Prairies; Steppes; Soil types; Edaphic factors; Site factors Abstract: The Water Erosion Prediction Project (WEPP) is a new water erosion prediction technology being developed by the USDA-Agricultural Research Service to replace the Universal Soil Loss Equation. Rangeland field experiments were designed to parameterize the WEPP rangeland erosion model. Included in the field experiments were plot treatments designed to separate direct from indirect effects of vegetation canopy on runoff and soil erosion. Nine rangeland sites from a wide range of soil and vegetation types were evaluated using rainfall simulation techniques. Natural versus clipped treatment surface characteristics and runoff and erosion responses were compared using regression analyses. These analyses showed that there were no significant differences between natural and clipped plot surface characteristics, runoff ratios, final infiltration rates, or initial rainfall abstractions. Erosion rates were different between treatments with the clipped plots having slightly less erosion than the natural plots. Results indicated that, under the rainfall conditions simulated, canopy cover was not directly contributing to initial abstractions through rainfall interception loss or significantly affecting runoff or erosion. 229 NAL Call. No.: QD241.T6 Regression models for some solute distribution equilibria in the terrestrial environment. Noegrohati, S.; Hammers, W.E. Reading : Gordon and Breach Science Publishers; 1992. Toxicological and environmental chemistry v. 34 (2/4): p. 175-185; 1992. Includes references. Language: English

Descriptors: Organochlorine insecticides; Soil; Sorption; Solvents; Leaching; Regression analysis Abstract: Sorption coefficients (K(p)) of several organochlorine insecticides (OCs) in volcanic ash silt from Central Java are presented. Selected experimental and estimated octanol-water partition coefficient (P) values are used to study log-log regressions with K(p) data collected from the literature (PAHs, chlorophenols, phenylureas, chloro- s-triazines, carbamates and organophosphorus insecticides) and those of the OCs determined in the present study. Leaching distances and bioactivities in soil are correlated with the K(p) values of the pesticides, and with the organic matter and the water content of the soil. 230 NAL Call. No.: HC79.P55J6 Regulating agricultural contamination of groundwater through strict liability and negligence legislation. Wetzstein, M.E.; Centner, T.J. Orlando, Fla. : Academic Press; 1992 Jan. Journal of environmental economics and management v. 22 (1): p. 1-11; 1992 Jan. Includes references. Language: English Descriptors: Georgia; Idaho; Iowa; Minnesota; Vermont; Groundwater pollution; Environmental legislation; Regulations; Legal liability; Game theory; Dynamic models; Agricultural chemicals Abstract: New state and national legislation attempts to limit the liability of agricultural chemical users by emasculating existing strict liability standards and replacing them with negligence standards. The allocation of contamination costs and precaution level between producers and victims of contamination associated with these alternative legislative standards is investigated. The analysis employed is a dynamic game theoretic framework considering moral hazard. Based on this analysis, a new institutional response is recommended to assign property rights based upon propensity and severity of injury and to require victim precaution. 231 NAL Call. No.: 292.8 W295 The regulation of groundwater quality with delayed responses. Kim, C.S.; Hostetler, J.; Amacher, G. Washington, D.C. : American Geophysical Union; 1993 May. Water resources research v. 29 (5): p. 1369-1377; 1993 May. Includes references. Language: English Descriptors: Groundwater pollution; Pollution control; Groundwater; Water quality; Regulations; Dynamic models; Algorithms; Nitrogen fertilizers; Farm inputs; Leachates; Nitrates; Usage; Costs; Agricultural policy

Abstract: This research develops a dynamic model of input regulation in the presence of externalities that do not occur simultaneously with input use. The model is formulated to study the regulation of firms that apply fertilizer, where leachate from the application of fertilizer accumulates in groundwater over time. In the model we show the derivation of an optimal nitrogen user fee and the consequences of regulatory design when time lags between nitrogen application and nitrate contamination are present. This research also responds to the need of developing a general solution algorithm for an optimal control model when the control variable exhibits a delayed response. A multistage solution algorithm presented in this paper is different from other studies in that a typical relationship is not assumed for the state and adjoint variables. 232 NAL Call. No.: HC79.P55J6 The regulation of non-point source pollution under imperfect and asymmetric information. Cabe, R.; Herriges, J.A. Orlando, Fla. : Academic Press; 1992 Mar. Journal of environmental economics and management v. 22 (2): p. 134-146; 1992 Mar. Includes references. Language: English Descriptors: Pollution; Control methods; Agricultural chemicals; Information; Costs; Reliability; Bayesian theory; Regulations; Taxes; Farmers' attitudes; Beliefs; Mathematical models Abstract: This paper develops a Bayesian framework for discussing the role of information in the design of non-point- source pollution control mechanisms. An ambient concentration tax is examined, allowing for spatial transport among multiple zones. Imposition of the tax requires costly measurement of concentrations in selected zones, and the selection of zones for measurement must be undertaken without perfect information regarding several parameters of the problem. Potentially crucial information issues discussed include: (a) the impact of asymmetric priors regarding fate and transport. (b) the cost of measuring ambient concentration, and (c) the optimal acquisition of information regarding fate and transport. 233 NAL Call. No.: 10 J822 Relating the nitrogen fertilizer needs of winter wheat crops to the soil's mineral nitrogen. Influence of the downward movement of nitrate during winter and spring. Addiscott, T.M.; Darby, R.J. Cambridge : Cambridge University Press; 1991 Oct. The Journal of agricultural science v. 117 (pt.2): p. 241-249; 1991 Oct. Includes references. Language: English

Descriptors: Triticum aestivum; Fertilizer requirement determination; Leaching; Mineralization; Nitrates; Nitrogen fertilizers; Simulation models; Soil fertility 234 NAL Call. No.: QH540.N3 Risk analysis for water supply from a river polluted by nitrate runoff. Plate, E.J.; Duckstein, L. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 30: p. 67-79; 1991. In the series analytic: Nitrate contamination: Exposure, consequence, and control / edited by I. Bogardi and R.D. Kuzelka. Proceedings of the NATO Advanced Research Workshop on Nitrate Contamination: Exposure, Consequences, and Control, September 9-14, 1990, Lincoln, Nebraska. Includes references. Language: English Descriptors: German federal republic; Nitrate; Nitrate fertilizers; Water pollution; Rivers; Runoff; Water quality; Risk; Drainage; Farmland; Stochastic models 235 NAL Call. No.: QH540.N3 Risk analysis of groundwater contamination. Ganoulis, J. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p. 455-474; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Victoria; Groundwater pollution; Pollutants; Hydrodynamics; Transport processes; Groundwater flow; Aquifers; Mathematical models; Risk; Saline water; Irrigation water 236 NAL Call. No.: QH540.N3 A river water quality management model for Canal de Isabel. II. Comunidad de Madrid. Cubillo, F.; Rodriguez, B. Berlin, W. Ger. : Springer-Verlag; 1991. NATO ASI series : Series G : Ecological sciences v. 26: p. 375-385; 1991. In the series analytic: Decision support systems: Water resources planning / edited by D.P. Loucks and J.R. da Costa. Proceedings of the NATO Advanced Research Workshop on Computer-Aided Support Systems for Water Resources, Research and Management, September 24-28, 1990, Ericeira, Portugal. Includes references.

Language: English Descriptors: Spain; Water management; Rivers; Water quality; Water pollution; Waste water treatment; Simulation models; Computer simulation; Computer software 237 NAL Call. No.: SB610.W39 The role of sensitivity analysis in groundwater risk modeling for pesticides. Fontaine, D.D.; Havens, P.L.; Blau, G.E.; Tillotson, P.M. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 716-724; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Simulation models; Pesticides; Leaching; Groundwater; Methodology 238 NAL Call. No.: 56.8 J822 Runoff characteristics of sagebrush rangelands: modeling implications. Wilcox, B.P.; Seyfried, M.S.; Cooley, K.R.; Hanson, C.L. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Mar. Journal of soil and water conservation v. 46 (2): p. 153-158; 1991 Mar. Includes references. Language: English Descriptors: Rangelands; Runoff; Computer simulation; Prediction; Watersheds; Precipitation 239 NAL Call. No.: 292.8 W295 Runoff contamination by soil chemicals: time scale approach. Wallach, R. Washington, D.C. : American Geophysical Union; 1991 Feb. Water resources research v. 27 (2): p. 215-223; 1991 Feb. Includes references. Language: English Descriptors: Runoff; Runoff water; Chemicals; Contamination; Overland flow; Soil solution; Transport processes; Profiles; Mathematical models Abstract: Two mass balance equations were used to model the transfer of dissolved chemicals from the soil solution to the surface runoff water and transport of these chemicals to the field outlet end. One mass balance equation is written for the chemicals dissolved in the overland water, and the other for the chemicals within the soil profile. The chemical input into the surface runoff water is by the rate-limited convective

mass transfer process. Two time scales are isolated: the slow time scale represents the diffusion-based mass transfer process and the fast time scale represents the convective transport of dissolved chemicals by overland flow. Scaling the mass balance equations for the slow time scale yields a small parameter, which multiplies the time derivative of the mass balance equation written for the overland flow, providing a singular perturbation problem. By using the method of matched asymptotic expansion, an inner and outer problem is formulated and solved for each order of approximation. A single composite expansion, uniformly valid over the entire domain, is derived analytically. This approximated solution was compared with an exact analytical solution for the case in which chemicals are initially uniformly distributed throughout a semi-infinite soil profile. The time scale method was then used to solve a more complicated problem in which chemicals are initially distributed within a certain soil surface layer of a semi- infinite soil profile. 240 NAL Call. No.: 290.9 AM32T Runoff curve numbers determined by three methods under conventional and conservation tillages. Yoo, K.H.; Yoon, K.S.; Soileau, J.M. St. Joseph, Mich. : American Society of Agricultural Engineers; 1993 Jan. Transactions of the ASAE v. 36 (1): p. 57-63; 1993 Jan. Includes references. Language: English Descriptors: Alabama; Runoff; Tillage; Traditional farming; Conservation tillage; Gossypium; Mathematical models Abstract: Event-based rainfall and the associated runoff data collected from a small watershed planted to cotton were analyzed to determine effects of two tillage systems on SCS runoff curve numbers. A tillage study was conducted for six years on a 3.8 ha watershed planted to cotton in the Limestone Valley region of northern Alabama. The tillage included three years of conventional (CvT), followed by three years of conservation tillage (CsT). Soils of the watershed are Decatur (clayey, kaolinitic, thermic Rhodic Paleudults) and Emory silt loam (fine-silty, siliceous, thermic Fluventic Umbric Dystrochrepts) which are classified in Hydrologic Soil Group B. Curve numbers (CN) were determined by the SCS method and a method developed assuming a log-normal probability distribution of potential maximum retention, S. The published CN of the average soil moisture condition or antecedent moisture condition II (AMC II) for the study site are 78 and 75 for CvT and CsT, respectively, which are recommended in many watershed/water quality computer simulation models such as CREAMS and AGNPS. The results showed that CN of AMC II (CN- II) calculated by the log-normal method were 83 and 88 for CvT and CsT, respectively. These were slightly higher than those calculated by the SCS method which were 82 for CvT and 86 for CsT. The calculated CN-II values were higher than the published CN-II values but the order of magnitude was

reversed. 241 NAL Call. No.: 290.9 AM32T Runoff curve numbers for the southern High Plains. Hauser, V.L.; Jones, O.R. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Jan. Transactions of the ASAE v. 34 (1): p. 142-148; 1991 Jan. Includes references. Language: English Descriptors: Southern plains states of U.S.A.; Runoff; Surface water; Water erosion; Water quality; Watersheds; Mathematical models; Rain; Soil conservation Abstract: Rainfall produces significant amounts of surface runoff from cultivated drylands of the western Great Plains. Currently, engineers must extrapolate runoff data from more humid regions to estimate runoff from farm fields. Runoff data are now available from a 32-year record in the semiarid, western Great Plains. We derived curve numbers (CN) for the Soil Conservation Service curve number method for three field- sized watersheds that were dryland-farmed in a wheat-sorghum- fallow crop sequence. The watershed soils are classified in hydrologic group D. The CNs for wheat and sorghum should be 79 and 82, respectively (handbook CN are both 80). The single handbook CN for fallow (90) is too high; it should be 77 for fallow after wheat and 82 for fallow after sorghum. These new CNs should improve computer model predictions of runoff, erosion and water quality, and provide more accurate estimates of runoff volume for use in designing conservation structures, water supply, flood control, and numerous other uses. 242 NAL Call. No.: 60.18 J82 Runoff prediction from sagebrush rangelands using water erosion prediction project (WEPP) technology. Wilcox, B.P.; Sbaa, M.; Blackburn, W.H.; Milligan, J.H. Denver, Colo. : Society for Range Management; 1992 Sep. Journal of range management v. 45 (5): p. 470-474; 1992 Sep. Includes references. Language: English Descriptors: Artemisia tridentata; Rangelands; Grassland management; Water erosion; Erosion control; Runoff; Prediction; Simulation models; Mathematical models Abstract: Runoff prediction is an important component of any process-based soil erosion model. In this paper we evaluate the runoff prediction capabilities of a new soil erosion model, WEPP, on sagebrush rangelands. Particular attention was given to the parameter estimation techniques used in WEPP to predict infiltration. Runoff volume predicted by WEPP is based on the Green and Ampt infiltration equation. Predicted runoff was compared to observed runoff from 90 large plot rainfall

simulation experiments on sagebrush rangelands. There was a poor correlation between predicted and observed runoff when the Green and Ampt parameters were estimated using the parameter estimation techniques. Runoff prediction was improved when parameters were determined from field measurements. Additional refinement of the Green and Ampt parameterization techniques is needed for continued improvement of WEPP. 243 NAL Call. No.: 56.8 SO3 Saline and sodic-saline soil reclamation: first order kinetic model. Selassie, T.G.; Jurinak, J.J.; Dudley, L.M. Baltimore, Md. : Williams & Wilkins; 1992 Jul. Soil science v. 154 (1): p. 1-7; 1992 Jul. Includes references. Language: English Descriptors: Saline sodic soils; Saline soils; Reclamation; Leaching; Kinetics; Soil water movement; Saturated conditions; Drained conditions; Salts in soil; Sodium; Solutes; Movement in soil; Electrical conductivity; Exchangeable sodium; Adsorption; Ratios; Ion exchange; Diffusion 244 NAL Call. No.: 56.8 SO3 A scaled sorption model validated at the column scale to predict cadmium contents in a spatially variable field soil. Boekhold, A.E.; Zee, S.E.A.T.M. van der Baltimore, Md. : Williams & Wilkins; 1992 Aug. Soil science v. 154 (2): p. 105-112; 1992 Aug. Includes references. Language: English Descriptors: Netherlands; Spodosols; Arable soils; Polluted soils; Cadmium; Sorption; Mathematical models; Validity; Soil ph; Soil organic matter; Soil variability; Spatial variation; Soil solution; Sorption isotherms; Transport processes 245 NAL Call. No.: SB610.W39 Screening procedure for soils and pesticides for potential water quality impacts. Goss, D.W. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 701-708; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Pesticides; Losses from soil; Leaching; Water quality; Groundwater pollution; Simulation models

246 NAL Call. No.: 292.8 J82 The seasonal variation of streamwater chemistry in three forested Mediterranean catchments. Pinol, J.; Avila, A.; Roda, F. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Dec. Journal of hydrology v. 140 (1/4): p. 119-141; 1992 Dec. Includes references. Language: English Descriptors: Spain; Watersheds; Broadleaved evergreen forests; Streams; Water quality; Water content; Chemical properties; Stream flow; Seasonal variation; Discharge; Solutes; Ions; Soil water; Groundwater; Temperature; Catchment hydrology; Mediterranean climate; Mathematical models Abstract: Streamwater chemistry is described for three streams draining undisturbed, evergreen broad-leaved forested catchments on phyllites in NE Spain: two streams with no or negligible flow in summer are located in the Prades massif, and one perennial stream is in the wetter Montseny mountains. Weekly data for a study period of 24 years are provided to (1) describe the seasonal variations in streamwater chemistry, (2) analyse the relationship between stream discharge and solute concentrations using a two-component mixing model and (3) search for patterns of temporal variation in stream solute concentrations after discounting the effects of discharge. At Prades, concentrations of all analysed ions, except NO3(-1), showed marked seasonal variations in stream water, whereas at Montseny only ions related to mineral weathering (HCO3(-1), Na+, Ca2+ and Mg2+) showed strong seasonality. Ion concentrations were more closely dependent on instantaneous discharge at Montseny than at Prades. The residuals of the relationship between solute concentrations and discharge retained a strong seasonality at Prades, but not at Montseny. These differences are related to the major hydrochemical processes that determine the streamwater chemistry at each site. The same processes are probably operative in the three catchments, but are of varying relative importance. At Montseny, the mixing of waters of different chemical composition seems to be the major process controlling streamwater chemistry, although the soilwater end-member composition predicted by the mixing model applied did not match the measured soilwater chemistry. In the drier Prades catchments, the two major hydrochemical processes determining the seasonal variation of streamwater chemistry are (1) the restart of flow after the summer drought, which flushes out the solutes accumulated during the dry period, and (2) the seasonal changes in groundwater chemistry that result from the interplay of water residence time, temperature and CO 247 NAL Call. No.: 292.8 W295 The second Las Cruces Trench experiment: experimental results and two-dimensional flow predictions.

Hills, R.G.; Wierenga, P.J.; Hudson, D.B.; Kirkland, M.R. Washington, D.C. : American Geophysical Union; 1991 Oct. Water resources research v. 27 (10): p. 2707-2718; 1991 Oct. Includes references. Language: English Descriptors: New Mexico; Soil water; Water flow; Tritium; Bromide; Solutes; Transport processes; Infiltration; Redistribution; Semiarid soils; Soil variability; Measurement; Deterministic models; Prediction Abstract: As part of a comprehensive field study designed to provide data to test stochastic and deterministic models of water flow and contaminant transport in the vadose zone, several trench experiments were performed in the semiarid region of southern New Mexico. The first trench experiment is discussed by Wierenga et al. (this issue). During the second trench experiment, a 1.2 m wide by 12 m long area on the north side of and parallel to a 26.4 m long by 4.8 m wide by 6 m deep trench was irrigated with water containing tracers using a carefully controlled drip irrigation system. The irrigated area was heavily instrumented with tensiometers and neutron probe access tubes to monitor water movement, and with suction samplers to monitor solute transport. Water containing tritium and bromide was applied during the first 11.5 days of the study. Thereafter, water was applied without tracers for an additional 64 days. Both water movement and tracer movement were monitored in the subsoil during infiltration and redistribution. The experimental results indicate that water and bromide moved fairly uniformly during infiltration and the bromide moved ahead of the tritium due to anion exclusion during redistribution. Comparisons between measurements and predictions made with a two-dimensional model show qualitative agreement for two of the three water content measurement planes. Model predictions of tritium and bromide transport were not as satisfactory. Measurements of both tritium and bromide show localized areas of high relative concentrations and a large downward motion of bromide relative to tritium during redistribution. While the simple deterministic model does show larger downward motions for bromide than for tritium during redistribution, it does not predict the high concentrations of solute observed during infiltration, nor can it predict the heterogeneous behavior observed for tritium during infiltration and for bromide during redistribution. 248 NAL Call. No.: QE581.F4 1991 Sediment-nutrient transport during severe storms. Smith, S.J.; Sharpley, A.N.; Williams, J.R.; Berg, W.A.; Coleman, G.A. Washington, D.C.? : Federal Energy Regulatory Commission; 1991. Proceedings of the Fifth Federal Interagency Sedimentation Conference, 1991 / edited by Shou-Shan Fan and Yung-Huang Kuo ; sponsored by Subcommittee on Sedimentation of the Interagency Advisory Committee on Water Data. p. PS/48- PS/55; 1991. Includes references.

Language: English Descriptors: Oklahoma; Texas; Runoff; Geological sedimentation; Storms; Mathematical models; Prediction 249 NAL Call. No.: 56.9 SO3 Selenium mobility and distribution in irrigated and nonirrigated alluvial soils. Fio, J.L.; Fujii, R.; Deverel, S.J. Madison, Wis. : The Society; 1991 Sep. Soil Science Society of America journal v. 55 (5): p. 1313-1320; 1991 Sep. Includes references. Language: English Descriptors: California; Selenium; Salts in soil; Movement in soil; Alluvial soils; Irrigated soils; Alkaline soils; Solutes; Transport processes; Adsorption; Desorption; Irrigation; Drainage; Irrigation water; Drainage water; Dispersion; Mathematical models; Dissolving; Leaching; Groundwater; Oxidation; Saturated conditions; Spatial distribution; Soil depth; Gypsum; Hysteresis; Time lag; Physicochemical properties Abstract: Dissolution and leaching of soil salts by irrigation water is a primary source of Se to shallow groundwater in the western San Joaquin Valley, California. In this study, the mobility and distribution of selenite and selenate in soils with different irrigation and drainage histories was evaluated using sorption experiments and an advection-dispersion model. The sorption studies showed that selenate (15-12 400 micrograms Se L-1) is not adsorbed to soil whereas selenite (10-5000 micrograms Se L-1) is rapidly adsorbed. The time lag between adsorption and desorption of selenite is considerable, indicating a dependence of reaction rate on reaction direction (hysteresis). Selenite adsorption and desorption isotherms were different, and both were described with the Freundlich equation. Model results and chemical analyses of extracts from the soil samples showed that selenite is resistant to leaching and therefore can represent a potential long-term source of Se to groundwater. In contrast, selenate behaves as a conservative constituent under alkaline and oxidized conditions and is easily leached from soil. 250 NAL Call. No.: 292.8 W295 A semidiscrete model for water and solute movement in tile- drained soils. 1. Governing equations and solution. Kamra, S.K.; Singh, S.R.; Rao, K.V.G.K.; Van Genuchten, M.T. Washington, D.C. : American Geophysical Union; 1991 Sep. Water resources research v. 27 (9): p. 2439-2447; 1991 Sep. Includes references. Language: English

Descriptors: Drainage water; Solutes; Water flow; Movement in soil; Transport processes; Aquifers; Tile drainage; Prediction; Mathematical models Abstract: A finite element model has been developed to simulate solute transport in tile-drained soil-aquifer systems. Water flow in the unsaturated zone and to drains in the saturated zone was assumed to be at steady state. The model considers the transport of nonreactive solutes, as well as of reactive solutes whose behavior can be described by a distribution coefficient. The exact-in-time numerical solution yields explicit expressions for the concentration field at any future point in time without having to compute concentrations at intermediate times. The semidiscrete method involves the determination of an eigensystem of eigenvalues and eigenvectors of the coefficient matrix. The eigensystem may be complex (i.e., it may have imaginary components) due to asymmetry created by the convection term in the governing convection-dispersion equation. The proposed approach facilitates long-term predictions of concentrations in drainage effluents and of salt distributions in soil and groundwater. The accuracy of the model was verified by comparing model results with those based on an analytical solution for two-dimensional solute transport in groundwater. 251 NAL Call. No.: 292.8 W295 A semidiscrete model for water and solute movement in tile- drained soils. 2. Field validation and applications. Kamra, S.K.; Singh, S.R.; Rao, K.V.G.K.; Van Genuchten, M.T. Washington, D.C. : American Geophysical Union; 1991 Sep. Water resources research v. 27 (9): p. 2449-2456; 1991 Sep. Includes references. Language: English Descriptors: India; Drainage water; Solutes; Movement in soil; Tile drainage; Subsurface drainage; Depth; Spacing; Soil salinity; Water table; Effluents; Water quality; Aquifers; Simulation; Prediction; Mathematical models Abstract: An exact-in-time two-dimensional finite element model for simulating convective-dispersive solute transport in a tile-drained field is validated against observed data from a subsurface drainage experiment. The model is capable of predicting the long-term effects of different irrigation and drainage practices on the salt distribution in an artificially drained soil-aquifer system. The model was used to predict transient changes in the salinity of the soil, the shallow groundwater table, and the drain effluent. Results are also presented on the effects of imposing alternative drain spacing-depth combinations, initial groundwater salinities, solute distribution coefficients, and different types of layering of the aquifer, on the computed salinity distributions in the unsaturated zone, the groundwater, and the drain effluent.

252 NAL Call. No.: SB951.P47 Sensitivity analysis of a mathematical model for pesticide leaching to groundwater. Boesten, J.J.T.I. Essex : Elsevier Applied Science Publishers; 1991. Pesticide science v. 31 (3): p. 375-388; 1991. Includes references. Language: English Descriptors: Netherlands; Pesticides; Groundwater; Leaching; Mathematical models; Meteorological factors; Plants; Uptake; Water pollution; Soil properties; Zea mays; Sandy soils Abstract: The sensitivity of pesticide leaching to pesticide/soil properties and to meteorological conditions was assessed by calculations with an existing convection- dispersion model. The model assumes equilibrium sorption (Freundlich equation), first-order transformation kinetics and passive plant uptake. The extent of pesticide leaching was characterized by the percentage of the dose leached below 1 m depth. The calculations were carried out for a humic sand soil cropped with maize and exposed to Dutch weather conditions. In general, the percentage leached was found to be very sensitive to the sorption coefficient, the Freundlich exponent (describing the curvature of the isotherm) and the transformation rate. The percentage leached was moderately sensitive to weather conditions (wet/dry years), long-term sorption equilibration and the relationship between transformation rate and temperature. Sensitivity to the extent of plant uptake was only significant for pesticides with low sorption coefficients. Sensitivity to soil hydraulic properties was small. The effect of application in autumn instead of in spring was found to be very large for non- sorbing pesticides with short half-lives. The sensitivity to spatial variability in sorption coefficient and transformation rate was found to be substantial at low percentages leached. 253 NAL Call. No.: TD403.G7 A simple analytical approach for predicting nitrate concentrations in pumped ground water. Lerner, D.N.; Papatolios, K.T. Dublin, Ohio : Ground Water Pub. Co; 1993 May. Ground water v. 31 (3): p. 37-375; 1993 May. Includes references. Language: English Descriptors: England; Groundwater pollution; Pollutants; Nitrates; Wells; Groundwater recharge; Concentration; Prediction; Models; Aquifers Abstract: A simple analytical expression is presented which predicts how solute concentrations evolve with time in a pumped well. The basic expression is for uniform recharge and

uniform concentration of a conservative solute (e.g. nitrate) in the recharge. It shows that pumped concentrations are independent of pumping rates. The expression can be developed to allow for more complex patterns of recharge and solute loading, and an example is given with three zones of recharge and concentrations, induced river recharge, and a cross- boundary inflow. Predictions are made for Edgmond Bridge, a new pumping station which lies in a drift-filled valley in the Triassic sandstone aquifer of Shropshire, UK. The model predicts that concentrations of nitrate will stay below the drinking water limit for 78 years, although this would be substantially reduced if the aquifer were significantly layered or if nitrate loads from agriculture increased. Predictions were reevaluated after two years and found to be consistent with observed patterns once actual, rather than expected, conditions were incorporated in the model. 254 NAL Call. No.: 56.8 SO3 A simple, inverse model for estimating nitrogen reaction rates from soil column leaching experiments at steady water flow. Yamaguchi, T.; Moldrup, P.; Rolston, D.E.; Hansen, J.A. Baltimore, Md. : Williams & Wilkins; 1992 Dec. Soil science v. 154 (6): p. 490-496; 1992 Dec. Includes references. Language: English Descriptors: Soil analysis; Nitrification; Denitrification; Nitrogen; Transport processes; Movement in soil; Soil water movement; Leaching; Mathematical models 255 NAL Call. No.: S590.C63 Simple techniques for monitoring and predicting the movement of chemicals in a field soil. Phillips, I.R. New York, N.Y. : Marcel Dekker; 1992. Communications in soil science and plant analysis v. 23 (9/10): p. 965-980; 1992. Includes references. Language: English Descriptors: Leaching; Chemicals; Podzolic soils; Movement in soil; Soil water movement; Exchangeable sodium; Sodium; Calcium; Magnesium; Potassium; Bromide; Chloride; Soil solution; Cation exchange; Anion exchange; Soil depth; Mathematical models 256 NAL Call. No.: aZ5071.N3 Simulation models, GIS and nonpoint-source pollution--January 1988-June 1992. Holloway, D.; Makuch, J. Beltsville, Md. : The Library; 1992 Sep. Quick bibliography series - U.S. Department of Agriculture, National Agricultural Library (U.S.). (92-69): 43 p.; 1992 Sep. Bibliography.

Language: English Descriptors: Simulation models; Information systems; Groundwater pollution; Agricultural chemicals; Bibliographies 257 NAL Call. No.: 292.8 W295 Simulation of a two-pollutant, two-season pollution offset system for the Colorado River of Texas below Austin. Letson, D. Washington, D.C. : American Geophysical Union; 1992 May. Water resources research v. 28 (5): p. 1311-1318; 1992 May. Includes references. Language: English Descriptors: Texas; River water; Water pollution; Pollutants; Water quality; Environmental impact; Seasonal variation; Simulation models; Mathematical models Abstract: A pollution offset system is a discharge permit system in which transfers are made subject to a restriction that no violations of water quality standards occur at any location. Simulation of a pollution offset system with seasonal variation and multiple pollutants allows for comparison of the savings possible from these design features. A simulation model (Qual-TX) developed by the Texas Water Commission is applied to a case study region near Austin, Texas, yielding impact coefficients for an economic optimization model without investment whose least cost solution represents the theoretical equilibrium of a pollution offset system. The optimization model finds short-run savings of 17.5% for a pollution offset system, as compared to a command and control policy that would also achieve the dissolved oxygen standard. Seasonalvariation in permit design produces minimal effects; virtually all savings come from allowing pollution offsets for the two different pollutants. 258 NAL Call. No.: TD426.J68 Simulation of nitrogen dynamics and leaching from arable soils. Lotse, E.G.; Jabro, J.D.; Simmons, K.E.; Baker, D.E. Amsterdam : Elsevier; 1992 Aug. Journal of contaminant hydrology v. 10 (3): p. 183-196; 1992 Aug. Includes references. Language: English Descriptors: Pennsylvania; Arable soils; Soil chemistry; Nitrogen balance; Nitrogen; Uptake; Nitrate nitrogen; Storage; Profiles; Mineralization; Nitrification; Leaching; Simulation models; Water pollution 259 NAL Call. No.: 56.8 SO3 Simulation of one-dimensional nitrate transport through soil

and concomitant nitrate diminution. Sadeghi, A.M.; Kunishi, H.M. Baltimore, Md. : Williams & Wilkins; 1991 Nov. Soil science v. 152 (5): p. 333-339; 1991 Nov. Includes references. Language: English Descriptors: Maryland; Sandy loam soils; Clay loam soils; Nitrate; Ion transport; Movement in soil; Losses from soil systems; Leaching; Laboratory methods; Undisturbed sampling; Horizontal flow; Velocity; Dispersion; Sorption; Mathematical models; Simulation; Nitrate nitrogen; Potassium nitrate; Carbon; Phthalates; Nutrient sources; Hydrology; Watershed management; Denitrification 260 NAL Call. No.: 292.9 AM34 Simulation of sediment and plant nutrient losses by the CREAMS water quality model. Yoon, K.S.; Yoo, K.H.; Soileau, J.M.; Touchton, J.T. Bethesda, Md. : American Water Resources Association; 1992 Nov. Water resources bulletin v. 28 (6): p. 1013-1021; 1992 Nov. Includes references. Language: English Descriptors: Alabama; Gossypium hirsutum; Conservation tillage; Tillage; Erosion; Runoff; Nitrogen; Phosphorus; Losses from soil; Water quality; Water pollution; Catchment hydrology; Simulation models; Prediction Abstract: CREAMS was applied to a field-sized watershed planted to cotton in the Limestone Valley region of northern Alabama. The field was cultivated for three years with conventional tillage (CvT) followed by three years or conservation tillage (CsT). CREAMS is composed of three components: hydrology, erosion, and chemistry. Surface runoff and losses of sediment, N and P were simulated and results were compared with the observed data from the watershed. Curve numbers recommended in the CREAMS user's guide were not adequate for the watershed conditions. The hydrology submodel improved runoff simulation from CvT and CsT when field-data based curve numbers were used. The erosion submodel demonstrated that CsT reduced sediment loss more than CvT, even though CsT had higher runoff than CvT. The nutrient submodel based on the simulated runoff and sediment underpredicted N loss for both CvT and CsT. This submodel, however, accurately predicted P loss for CvT, but underpredicted for CsT (50 percent lower than the observed). The results of CREAMS simulation generally matched the observed order of magnitude for higher runoff, lower sediment, and higher N and P losses from CsT than from CvT. 261 NAL Call. No.: 292.8 J82 Simulation of water and chemicals in macropore soils. 2.

Application of linear filter theory. Chen, C.; Wagenet, R.J. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Jan. Journal of hydrology v. 130 (1/4): p. 127-149; 1992 Jan. Includes references. Language: English Descriptors: Macropores; Macropore flow; Water flow; Hydraulic conductivity; Soil water content; Transport processes; Linear models; Simulation Abstract: Description of flow in soils with macropores is difficult, yet quite important in describing the dynamics of field soils. Recognizing the two structural domains of the macropore and matrix, and possible water-flow situations, three flow regions have been suggested: matrix, macropore, and transaction. The matrix and the macropore are the two domains, and the transaction represents the exchange of water between the matrix and the macropore. As a beginning point for the description of such systems, linear filter theory is applied to the Richards equation to obtain a general set of analytical solutions for water and contaminant movement in unsaturated soil in which there are no macropores. To develop these solutions, it unique relationship between water flux (q) and water content (0) is demonstrated by executing a numerical simulation based on the Richards equation. By piece-wise curve fitting of q(0), it is possible to establish and obtain a set of equations which describe water flow and chemical movement in soil, and which take the form of linear filter systems, providing analytical solutions by convolution. A two-domain approach applies equations for homogeneous soil to describe the matrix domain, with the macropore domain described with coefficients obtained by applying the Poiseuille and Chezy equations. These equations are analytically solved in correspondence with the three flow situations, resulting in a model. LASOMS (linear analytical solutions of macropore soils). Simulations, data and model comparisons of LASOMS have shown the above solutions to be reasonable under several conditions. 262 NAL Call. No.: 292.8 J82 Simulation of water and chemicals in macropore soils. 2. Application of linear filter theory. Chen, C.; Wagenet, R.J. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Jan. Journal of hydrology v. 130 (1/4): p. 127-149; 1992 Jan. Includes references. Language: English Descriptors: Macropores; Macropore flow; Water flow; Hydraulic conductivity; Soil water content; Transport processes; Linear models; Simulation Abstract: Description of flow in soils with macropores is

difficult, yet quite important in describing the dynamics of field soils. Recognizing the two structural domains of the macropore and matrix, and possible water-flow situations, three flow regions have been suggested: matrix, macropore, and transaction. The matrix and the macropore are the two domains, and the transaction represents the exchange of water between the matrix and the macropore. As a beginning point for the description of such systems, linear filter theory is applied to the Richards equation to obtain a general set of analytical solutions for water and contaminant movement in unsaturated soil in which there are no macropores. To develop these solutions, it unique relationship between water flux (q) and water content (0) is demonstrated by executing a numerical simulation based on the Richards equation. By piece-wise curve fitting of q(0), it is possible to establish and obtain a set of equations which describe water flow and chemical movement in soil, and which take the form of linear filter systems, providing analytical solutions by convolution. A two-domain approach applies equations for homogeneous soil to describe the matrix domain, with the macropore domain described with coefficients obtained by applying the Poiseuille and Chezy equations. These equations are analytically solved in correspondence with the three flow situations, resulting in a model. LASOMS (linear analytical solutions of macropore soils). Simulations, data and model comparisons of LASOMS have shown the above solutions to be reasonable under several conditions. 263 NAL Call. No.: SB610.W39 Site-specific pesticide recommendations: the final step in environmental impact prevention. Hornsby, A.G. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 736-742; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Florida; Pesticides; Environmental impact; Leaching; Runoff; Toxicology; Soil properties; Water quality; Water pollution; Decision making; Methodology; Simulation models; Geographical information systems; Risk; Cooperative extension service 264 NAL Call. No.: S623.O94 1992 Soil erosion and sediment yield modeling, simulation and prediction. Overton, Donald E., Knoxville, TN : Stormwater Publications,; 1992. 197 p. : ill. (some col.) ; 23 cm. Includes bibliographical references and indexes. Language: English

Descriptors: Runoff; Soil erosion; Sediment transport 265 NAL Call. No.: 292.8 J82 Soil water content at R-5. 2. Impact of antecedent conditions on rainfall-runoff simulations. Loague, K. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Nov. Journal of hydrology v. 139 (1/4): p. 253-261; 1992 Nov. Includes references. Language: English Descriptors: Soil water content; Simulation models; Rain; Runoff; Watersheds; Spatial variation; Topsoil; Subsoil; Soil depth; Estimation Abstract: In this paper, the second part of a two-part series, the performance of a quasi-physically based rainfall- runoff model (QPBRRM) is evaluated for a set of 39 events from a small rangeland catchment (R-5) using a suite of alternative antecedent soil water content estimates. The data set used to glean antecedent conditions for the R-5 events, described in the companion paper contains 22 848 observations of soil water content made over a 4 year period. The performance of the model is improved by using estimates of antecedent soil water content that include consideration of spatial variability. 266 NAL Call. No.: 56.9 SO3 Soil water movement in response to temperature graidents: experimental measurements and model evaluation. Bach, L.B. Madison, Wis. : The Society; 1992 Jan. Soil Science Society of America journal v. 56 (1): p. 37-46; 1992 Jan. Includes references. Language: English Descriptors: Sandy loam soils; Soil water movement; Transport processes; Soil water; Spatial distribution; Soil temperature; Spatial variation; Laboratory methods; Measurement; Comparisons; Simulation models; Mathematical models; Soil water content; Heat flow; Thermal conductivity; Thermal diffusivity; Water vapor; Matric potential; Soil water retention Abstract: Temperature gradients may have a significant effect on soil water movement under certain conditions, but inclusion of these effects adds complexity to the flow analysis. This study was conducted to help clarify the significance of nonisothermal water flow, and to examine theoretical and numerical descriptions of the transport processes. At initial water contents of 0.00, 0.049, 0.099, 0.151, and 0.282 m3 m-3 isothermal and nonisothermal laboratory experiments were conducted to provide direct information on soil water movement

in response to temperature gradients. These data were used to evaluate the numerical simulation model SPLaSHWaTr2, and to examine calculation of the thermal conductivity, the thermal vapor diffusivity, and the temperature coefficient of the matric potential, based on modifications to a theory proposed by Philip and de Vries in 1957. A statistically significant effect of the temperature gradient was found at an initial water content of 0.151 m3 m-3, which corresponds to a pressure head of approximately -1.2 m of H2O. No effect of the temperature gradient was found at initial water contents of 0.00, 0.049, 0.099, or 0.282 m3 m-3. Under isothermal conditions, the model provided simulated water-content profiles that were in good agreement with measured profiles. Under nonisothermal conditions, profiles simulated by the model were in poor agreement with the measured data, using the original values of thermal conductivity, thermal vapor diffusivity and the temperature coefficient of the matric potential. Sensitivity analysis showed that thermal conductivity and thermal vapor diffusivity had a negligible influence on nonisothermal water movement. On the other hand, the temperature coefficient of the matric potential had a significant influence on nonisothermal water movement. Adjusting the temperature coefficient of the matric potential from the original value of -0.0068 K-1 to the value suggested by Philip and de Vries, -0.00209 K-1, improved the a 267 NAL Call. No.: 56.9 SO3 Solute transport in a two-layer medium investigated with time moments. Leij, F.J.; Dane, J.H. Madison, Wis. : The Society; 1991 Nov. Soil Science Society of America journal v. 55 (6): p. 1529-1535; 1991 Nov. Includes references. Language: English Descriptors: Layered soils; Transport processes; Solutes; Movement in soil; Statistical methods; Mathematical models; Soil boundaries; Interface; Soil water movement; Variance; Models; Spreading Abstract: The study of solute transport in porous media requires knowledge of the transport parameters. These transport parameters can be determined from data collected during displacement experiments using a number of mathematical procedures, among them the moment method. An advantage of this method is that it can also be used to theoretically analyze, and therefore enhance our understanding of, transport problems. We present theoretical time moments as derived from analytical solutions of the advection-dispersion equation in the Laplace domain for a step- and pulse-type solute input applied to a two-layer soil with steady flow transverse to layering. These moments were used for investigating the mean breakthrough time, u1, and variance, u2. It was shown that, theoretically, more retardation and spreading occurs for a third- than for a first-type boundary condition, but that the presence of the interface, as such, does not affect spreading

for either boundary condition. 268 NAL Call. No.: 56.8 SO3 Solute transport through hard pans of paddy fields. 2. Cation exchange processess. Ishiguro, M. Baltimore, Md. : Williams & Wilkins; 1992 Jan. Soil science v. 153 (1): p. 42-47; 1992 Jan. Includes references. Language: English Descriptors: Paddy soils; Compact soils; Pans; Disturbed soils; Solutes; Transport processes; Exchangeable cations; Movement in soil; Calcium ions; Strontium; Bromide; Simulation models; Laboratory methods; Mathematical models; Cation exchange; Cation exchange capacity; Adsorption; Equilibrium; Diffusivity; Roots; Pores; Pore volume 269 NAL Call. No.: 56.8 SO3 Solute transport through hard pans of paddy fields. I. Effect of vertical tubular pores made by rice roots on solute transport. Ishiguro, M. Baltimore, Md. : Williams & Wilkins; 1991 Dec. Soil science v. 152 (6): p. 432-439; 1991 Dec. Includes references. Language: English Descriptors: Oryza sativa; Paddy soils; Gley soils; Andosols; Lowland areas; Subsoil; Soil compaction; Transport processes; Bromine; Movement in soil; Macropores; Roots; Simulation; Measurement; Calculation; Mathematical models; Convection; Diffusion; Velocity; Pore volume 270 NAL Call. No.: QH540.J6 Sorptive reversibility of atrazine and metolachlor residues in field soil samples. Pignatello, J.J.; Huang, L.Q. Madison, Wis. : American Society of Agronomy; 1991 Jan. Journal of environmental quality v. 20 (1): p. 222-228; 1991 Jan. Includes references. Language: English Descriptors: Atrazine; Metolachlor; Herbicide residues; Measurement; Samples; Soil pollution; Sorption; Theory; Transport processes; Leaching; Mathematical models Abstract: Predictions of the fate and transport of organic compounds in soils depend on sound sorption models. The impacts of slowly reversible (nonequilibrium) sorption on compound fate are not well quantified. Soil samples containing

residues of the herbicides atrazine (2-chloro-4-ethylamino-6- isopropyl-1,3,5-triazine) and metolachlor (2-chloro-N-[2- ethyl-5-methylphenyl]-N-[2-methoxy-1-methylethyl]-acetamide) were collected from fields 2 to 15 mo after their last application to assess the sorptive reversibility of these residues. The apparent sorption constant of the native herbicide, Kapp was determined from the sorbed and solution concentrations after suspension of the sample in water for 24 h. The "equilibrium" sorption constant, Kd, was determined in the same samples from 24 h sorption isotherms of freshly added herbicide, taking into account the fraction of labile native herbicide (fL). The ratio Kapp/Kd varied from 2.3 to 42 and was directly related to the "age" of the residue (i.e, time between sampling and last application). The value of fL ranged from 0.056 to 0.60 and was inversely related to the age of the residue. The results indicate that contaminated samples collected from the field can contain a large fraction of contaminant in a slowly reversible sorbed state, and that this fraction increase with time. 271 NAL Call. No.: 501 L84B Spatio-temporal pattern formation in nonlinear non-equilibrium plankton dynamics. Malchow, H. London : The Society; 1993 Feb22. Proceedings of the Royal Society of London : Series B : Biological sciences v. 251 (1331): p. 103-109; 1993 Feb22. Includes references. Language: English Descriptors: Algae; Phytoplankton; Zooplankton; Aquatic communities; Indicator plants; Indicator species; Spatial distribution; Temporal variation; Water quality; Mathematical models 272 NAL Call. No.: 56.8 J822 Statewide GIS-based ranking of watersheds for agricultural pollution prevention. Hamlett, J.M.; Miller, D.A.; Day, R.L.; Peterson, G.W.; Baumer, G.M.; Russo, J. Ankeny, Iowa : Soil and Water Conservation Society of America; 1992 Sep. Journal of soil and water conservation v. 47 (5): p. 399-404; 1992 Sep. Includes references. Language: English Descriptors: Pollution; Watersheds; Ranking; Computer techniques; Models; Databases; Geography 273 NAL Call. No.: 292.8 W295 Statistical analysis of spatial variability in unsaturated flow parameters. Russo, D.; Bouton, M. Washington, D.C. : American Geophysical Union; 1992 Jul.

Water resources research v. 28 (7): p. 1911-1925; 1992 Jul. Includes references. Language: English Descriptors: Sandy loam soils; Unsaturated flow; Leaching; Soil properties; Hydraulic conductivity; Soil water retention; Spatial variation; Stochastic models; Statistical analysis; Autocorrelation; Prediction Abstract: Core scale estimates of soil parameters of the Gardner-Russo and van Genuchten models of the hydraulic conductivity and water retention functions were obtained for 417 undisturbed soil cores taken from a wall of a trench (20 m long, 2.5 m deep), using a procedure based on inverse problem methodology. These estimates were used to evaluate the first two statistical moments of the underlying random space functions (RSFs), using the restricted maximum likelihood estimation procedure, coupled with the weighted least squares procedure, to estimate parameters of models of the covariance and the drift functions of the pertinent RSFs. The fitted models were used to evaluate the mean and covariance functions of the hydraulic conductivity and water retention functions for given water saturations. Covariance functions of log- saturated conductivity (log Ks) and the "shape" parameters of the Gardner-Russo and van Genuchten models exhibited statistical anisotropy characterized by aspect ratios that vary between 3 to 4. Correlation scales of log Ks were larger than those of the "shape" parameters. Consequently, the product of the variance of log unsaturated conductivity and its correlation scale remained essentially invariant for a considerable range of water saturation. The implications of these results regarding stochastic modeling of transport in heterogeneous porous formations and possible applications of the results of this study are discussed briefly. 274 NAL Call. No.: TD426.J68 Statistical and graphical methods for evaluating solute transport models: Overview and application. Loague, K.; Green, R.E. Amsterdam : Elsevier; 1991 Jan. Journal of contaminant hydrology v. 7 (1/2): p. 51-73. maps; 1991 Jan. Includes references. Language: English Descriptors: Groundwater pollution; Pollutants; Persistence; Prediction; Mathematical models; Pesticides; Leaching 275 NAL Call. No.: 292.8 W295 Stochastic analysis of simulated vadose zone solute transport in a vertical cross section of heterogeneous soil during nonsteady water flow. Russo, D. Washington, D.C. : American Geophysical Union; 1991 Mar. Water resources research v. 27 (3): p. 267-283; 1991 Mar.

Includes references. Language: English Descriptors: Soil water; Solutes; Water flow; Unsaturated flow; Horizontal flow; Vertical movement; Transport processes; Hydraulic conductivity; Spatial variation; Stochastic models; Simulation Abstract: The problem of transport of a conservative nonreactive solute in a vertical cross section of a hypothetical partially saturated, scale-heterogeneous soil under transient water flow was analyzed here. It was assumed that locally the water flow and the solute transport can be described by the Richards' equation and by the one-component convection dispersion equation, respectively. The simulated water content and the solute concentration distributions in the vertical cross section of the soil at different elapsed times were quantified in terms of space averages and two-point autocorrelation functions. The time evolution of the solute plume was quantified in terms of its first two normalized spatial moments, from which the time dependence of the longitudinal and the transverse components of the solute velocity vector, and the spatial covariance tensor, were estimated. The results of this study, which are relevant to solute transport at the local or the plume scale, demonstrated the considerable variability in the solute concentration in space and time, due to the complex heterogeneity of the soil hydraulic properties in both the vertical and the horizontal directions. Consequently, the movement of the solute plume was characterized by a compression-expansion phenomenon, attributed to the decrease in the effective solute velocity through the zones of relatively fine-textured soil material. It was concluded that existing stochastic vadose zone transport models may be applicable to shallow depths but may fail to describe the actual spread of a solute plume when the transport takes place at relatively large depths, mainly because of the neglect of the significant vertical heterogeneity in the soil hydraulic properties. 276 NAL Call. No.: 292.8 J82 Stochastic modelling of solute flux in the unsaturated zone at the field scale. Destouni, G. Amsterdam : Elsevier Scientific Publishers, B.V.; 1993 Mar01. Journal of hydrology v. 143 (1/2): p. 46-61; 1993 Mar01. Special Issue: Modelling Flow and Transport in the Unsaturated Zone: Scale Problems and Spatial Variability. Includes references. Language: English Descriptors: Solutes; Unsaturated flow; Transport processes; Spatial variation; Saturated hydraulic conductivity; Pore size distribution; Mathematical models

Abstract: Spatial variability in both the saturated hydraulic conductivity and the pore-size distribution is incorporated in a stochastic model of field-scale solute transport through the unsaturated zone. The transport model considered is based on a Lagrangian framework, in which the expected field-scale solute flux and the associated uncertainty in predictions are defined from distributions of solute travel time. Expressions for such travel time distributions are derived from statistical information on measurable soil hydraulic properties and are used to analyze the statistics of the field-scale solute flux in heterogeneous soil. The spatial variability in the saturated hydraulic conductivity and in the pore-size distribution has a similar effect on the prediction uncertainty, quantified by the variance of the solute flux, as on the expected breakthrough curve. The effect on the relative prediction uncertainty, quantified by the coefficient of variation for the solute flux, is therefore small. Both the solute flux variance and the coefficient of variation decrease rapidly with increasing size of the input domain and are considerably smaller for a planar source than for a linear one. 277 NAL Call. No.: QD1.A45 Study design to investigate and simulate agrochemical movement and fate in groundwater recharge. Asmussen, L.E.; Smith, C.N. Washington, D.C. : The Society; 1991. ACS Symposium series - American Chemical Society (465): p. 150-164; 1991. In the series analytic: Groundwater residue sampling design / edited by R.G. Nash and A.R. Leslie. Includes references. Language: English Descriptors: Georgia; Groundwater; Agricultural chemicals; Water quality; Water pollution; Sampling; Mathematical models Abstract: The vulnerability of aquifers to contamination by agrochemicals is relatively high in the southeastern Coastal Plain. Transport and fate of agrochemicals in either the root, unsaturated, or saturated zones can be simulated by existing mathematical models. However, a linked mathematical model is needed to simulate the movement and degradation from the point of application through the unsaturated zone, and into groundwater. The United States Geological Survey and Agricultural Research Service initiated a cooperative investigation in 1986. In 1988, the United States Environmental Protection Agency joined the research investigation. These agencies are sharing technical expertise and resources to develop an understanding of physical, chemical, and biological processes and to evaluate their spatial and temporal variability; and to develop and validate linked model(s) that would describe chemical transport and fate. Study sites have been selected in the Fall Line Hills district of the Coastal Plain province. The Claiborne aquifer recharge area is located in this district near Plains,

Georgia. Instrumentation to measure water and chemical transport has been installed. 278 NAL Call. No.: TD899.P3N34 no.618 Supplemental user's guide for applying the WASP4 model program. National Council of the Paper Industry for Air and Stream Improvement (U.S.) New York, N.Y. : National Council of the Paper Industry for Air and Stream Improvement,; 1991. 2 v. : ill. ; 28 cm. (Technical bulletin (National Council of the Paper Industry for Air and Stream Improvement (U.S.) : 1981) ; no. 618.). Cover title. "September 1991"--Cover. Includes bibliographical references. Language: English Descriptors: Water quality; Information storage and retrieval systems 279 NAL Call. No.: 292.8 J82 Surface runoff and soil water percolation as affected by snow and soil frost. Johnsson, H.; Lundin, L.C. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Jan. Journal of hydrology v. 122 (1/4): p. 141-159; 1991 Jan. Includes references. Language: English Descriptors: Arable soils; Frost; Snow; Spatial variation; Infiltration; Water flow; Drainage; Soil water content; Unfrozen water; Soil temperature; Frozen conditions; Soil depth; Soil pore system; Simulation models Abstract: A coupled soil water and heat model was used to study the influence of soil frost and snow on infiltration and drainage flow in an agricultural field in central Sweden. An analogy between freezing/thawing and drying/wetting was assumed for the soil frost submodel. Model simulations were evaluated against measurements of total soil water content, unfrozen water content, soil temperature and drainage water- flow. The influences of soil frost and spatial variation in snow cover were studied by simulation of possible extreme situations in the field. The model accurately described the dynamics of soil temperature and water contents; however, infiltration and field drainage flow were considerably underestimated and delayed by about three weeks under frozen conditions. A model simulation, discounting the effects of soil frost, overestimated the drain response. An attempt at simulating the field variation in snow cover by assuming possible 'sink points' for snowmelt, explained part of the deviations between simulated and measured drain flows. A basis for a new model formulation of the infiltration and percolation processes in frozen soil is proposed in which two water-flow domains are assumed, one low-flow domain in the fine pores. smaller than those filled with ice, and one high- flow domain in the large air-filled pores. This allows the

simulation of rapid infiltration in large ice-free pores and drainage flow under frozen conditions as well as the resulting redistribution of ice from smaller to larger pores. 280 NAL Call. No.: 292.8 W295 Surface runoff contamination by chemicals initially incorporated below the soil surface. Wallach, R.; Shabtai, R. Washington, D.C. : American Geophysical Union; 1993 Mar. Water resources research v. 29 (3): p. 697-704; 1993 Mar. Includes references. Language: English Descriptors: Runoff; Overland flow; Agricultural chemicals; Contamination; Clay soils; Silt loam soils; Incorporation; Soil depth; Mathematical models; Prediction Abstract: One method of reducing the contamination of overland flow by soil chemicals (e.g., nutrients, pesticides) is to reduce their concentration at the immediate soil surface. This can be done by incorporating the chemicals at lower depths, by either tilling the soil or by irrigating shortly after chemical application. A mathematical model designed to predict the runoff concentration of chemicals initially, located at different depths below the soil surface is presented. The model accounts for transient water infiltration and convective-dispersive solute transport in the soil, and also considers rate-limited mass transfer through a laminar boundary layer at the soil surface/runoff water interface. Sorption-desorption interactions between soil and chemicals are assumed to be subject to linear isotherms or to first-order kinetics. The dissolved chemical concentrations at the soil surface and in the surface runoff were simulated for coarse and fine soils at different antecedent soil moistures and rainfall intensities. The simulation indicated that the initial depth of chemical incorporation below the soil surface is negatively correlated to the dissolved chemical concentration at the soil surface and in runoff water. A basic and characteristic difference between the chemical whose retention by the soil solids is expressed by an equilibrium model and the one whose retention is expressed by a kinetic model is soil surface concentration during water and chemical redistribution following the termination of rainfall and runoff. Contrary, to the instantaneous equilibrium-type chemicals, the dissolved concentration of the kinetic-type chemicals increases sharply to its final value. For the coarser soil with higher saturated hydraulic conductivity, the relative chemical concentrations in surface runoff are lower than for the finer soil, when similar values of initial pressure head psi (0) and rainfall intensities (three times the saturated hydraulic conductivity of each soil) are 281 NAL Call. No.: 292.8 W295 Surface runoff contamination by soil chemicals: simulations

for equilibrium and first-order kinetics. Wallach, R.; Shabtai, R. Washington, D.C. : American Geophysical Union; 1992 Jan. Water resources research v. 28 (1): p. 167-173; 1992 Jan. Includes references. Language: English Descriptors: Agricultural chemicals; Solutes; Runoff; Overland flow; Contamination; Soil water content; Rain; Sloping land; Infiltration; Transport processes; Sorption; Desorption; Kinetics; Prediction; Mathematical models Abstract: A model was developed to predict the potential contamination of overland flow by chemicals removed from soil water by rainfall on sloping soil. The model accounts for transient water infiltration and convective-dispersive solute transport in the soil and also considers rate-limited mass transfer through a laminar boundary layer at the soil surface/runoff water interface. Sorption-desorption interactions between soil and chemicals are assumed to be subject to linear and nonlinear isotherms or to first-order kinetics. The dissolved-chemical concentrations at the soil surface and in the surface runoff were determined for different antecedent soil moistures and rainfall intensities. These concentrations are lower when the antecedent moisture is low because the time of ponding for drier soil is longer and because during that period soil solutes are displaced by greater volumes of infiltrating water. For a specified initial soil water content, higher rainfall rates cause higher dissolved-chemical concentrations at the soil surface. The degree of nonlinearity of the equilibrium isotherm greatly affects the transient dissolved-chemical concentrations and the linear isotherm cannot always be used as an alternative. These concentrations are also greatly affected by the value of the kinetics rate coefficient. In the first-order kinetics model there is a recovery of the dissolved-chemical concentration at the soil surface during the period between rainstorms. As a result, the initial concentration at the soil surface for the subsequent rainstorm is higher than that expected when equilibrium is assumed. 282 NAL Call. No.: Q320.B56 Surface transport of microorganisms by water. Moore, J.A. Stoneham, Mass. : Butterworth Publishers; 1991. Biotechnology (15): p. 41-55; 1991. In the Series Analytic: Assessing Ecological Risks of Biotechnology / edited by Lev R. Ginzburg. Includes references. Language: English Descriptors: Contaminants; Microbial contamination; Movement; Water transport; Runoff water; Models

283 NAL Call. No.: TD420.A1P7 System modeling approach for solute transport through upper soils. Liu, C.C.K.; Feng, J.S.; Chen, W. Oxford : Pergamon Press; 1991. Water science and technology : a journal of the International Association on Water Pollution Research and Control v. 24 (6): p. 67-72; 1991. In the series analytic: Watermatex '91 / edited by T.O. Barnwell, P.J. Ossenbruggen and M.B. Beck. Proceedings of the "Second International Conference on Systems Analysis in Water Quality Management," June 3-6, 1991, Durham, New Hampshire. Includes references. Language: English Descriptors: Hawaii; Soil; Surface layers; Solutes; Movement in soil; Agricultural chemicals; Groundwater pollution; Physical models; Simulation models; Systems approach; Case studies; Fenamiphos; Transport processes 284 NAL Call. No.: S671.A66 Targeting animal waste pollution potential using a geographic information system. Heatwole, C.D.; Shanholtz, V.O. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Nov. Applied engineering in agriculture v. 7 (6): p. 692-698; 1991 Nov. Includes references. Language: English Descriptors: Virginia; Water pollution; Animal wastes; Site factors; Geography; Environmental impact; Models; Screening; Indexes; Ranking Abstract: Data on livestock operations were added as a data layer and corresponding attribute table to the Virginia Geographic Information System (VirGIS) for seven counties in Virginia. A simple model calculates an animal waste pollution index (AWPI) which rates each site based on waste load, slope, and distance-to-stream. These factors are considered both for the facility as well as for the potential land application area surrounding the farm site. The geographic information system (GIS) database and model were used to produce maps and corresponding tables of facilities ranked by AWPI. Outputs were used as a screening tool to identify high-risk sites. Model evaluation based on 1253 farm sites in Rockingham County and 311 sites in Augusta County indicate a balance in site versus application area contribution to AWPI. For these two counties, the distribution of AWPI ratings is conducive to effective targeting. No relationship between animal type and AWPI was evident. 285 NAL Call. No.: 56.8 J822 Teaching land management with a microcomputer-based model. Ross, D.; Nash, T.; Harbor, J. Ankeny, Iowa : Soil and Water Conservation Society of America;

1992 May. Journal of soil and water conservation v. 47 (3): p. 226-230; 1992 May. Includes references. Language: English Descriptors: Land management; Soil conservation; Teaching methods; Land use; Computer assisted instruction; Microcomputers; Computer simulation; Simulation models; Universal soil loss equation; Water erosion; Runoff; Measurement; Erosion control; Sediment; Geological sedimentation; Gully erosion; Land types 286 NAL Call. No.: GB701.W375 no.91-4068 Techniques for estimating selected parameters of the U.S. Geological Survey's Precipitation-Runoff Modeling System in eastern Montana and northeastern Wyoming. Cary, Lawrence E. United States, Bureau of Land Management, Geological Survey (U.S.) Helena, Mont. : U.S. Dept. of the Interior, U.S. Geological Survey ; Denver, CO : Books and Open-File Reports Section [distributor,; 1991; I 19.42/4:91-4068. iv, 39 p. : ill., maps ; 28 cm. (Water-resources investigations report ; 91-4068). Shipping list no.: 92-047- P. November 1991. Includes bibliographical references (p. 36-39). Language: English; English Descriptors: Precipitation (Meteorology); Hydrologic cycle; Watersheds 287 NAL Call. No.: 56.8 J822 Terrain analysis: integration into the agricultural nonpoint source (AGNPS) pollution model. Panuska, J.C.; Moore, I.D.; Kramer, L.A. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Jan. Journal of soil and water conservation v. 46 (1): p. 59-64; 1991 Jan. Includes references. Language: English Descriptors: Terrain; Pollution; Water quality; Erosion; Computer simulation 288 NAL Call. No.: 56.9 SO3 A test of the local equilibrium assumption for adsorption and transport of picloram. Gaber, H.M.; Comfort, S.D.; Inskeep, W.P.; El-Attar, H.A. Madison, Wis. : The Society; 1992 Sep. Soil Science Society of America journal v. 56 (5): p. 1392-1400; 1992 Sep. Includes references. Language: English

Descriptors: Silt loam soils; Picloram; Movement in soil; Equilibrium; Transport processes; Adsorption; Sorption isotherms; Soil water; Soil pore system; Soil water movement; Velocity; Kinetics; Mathematical models; Bromine Abstract: The inability of transport models that use a local equilibrium assumption (LEA) to describe contaminant transport under certain conditions has led to the development of various criteria for assessing LEA applicability. Our objectives were to determine the influence of pore water velocity on the adsorption and transport of picloram (4-amino-3,5,6-trichloropicolinic acid) and evaluate the use of dimensionless Damkohler numbers for identifying experimental conditions conducive to nonequilibrium transport. Three sets of transport experiments were conducted to study the movement of Br- and picloram through an Amsterdam silt loam soil (fine-silty, mixed Typic Haploboroll). Experiments were performed by displacing a 100-mL Br-14C-labeled picloram pulse through disturbed soil columns (5.1-cm diam, 30-cm length) at pore water velocities of 4.1, 40.6, and 200.1 cm d-1. The kinetic parameters of picloram adsorption and desorption were obtained independently. Results indicated that Br- breakthrough curves (BTCs) were symmetrical at each pore water velocity. In contrast, picloram BTCs were shifted to the left on a pore-volume basis and demonstrated increased tailing with increasing pore water velocities. The use of LEA with a batch-determined distribution coefficient (Kd) in the convection-dispersion equation adequately described picloram BTCs at the 4.1 cm d-1 pore water velocity, but overestimated the elution time at faster pore water velocities. These observations were consistent with conclusions derived from criteria used to assess LEA applicability and indicate that knowledge of reaction kinetics and convective velocities can be easily used to identity conditions conducive to nonequilibrium transport. 289 NAL Call. No.: QH540.J6 Tests of the pesticide root zone model and the aggregate model for transport and transformation of aldicarb, metolachlor, and bromide. Parrish, R.S.; Smith, C.N.; Fong, F.K. Madison, Wis. : American Society of Agronomy; 1992 Oct. Journal of environmental quality v. 21 (4): p. 685-697; 1992 Oct. Includes references. Language: English Descriptors: Aldicarb; Metolachlor; Bromide; Tracers; Profiles; Leaching; Vertical movement; Pesticide residues; Soil water movement; Sorption; Soil depth; Velocity; Dispersion; Mathematical models; Simulation models; Prediction Abstract: Mathematical models are widely used to predict leaching of pesticides and nutrients in agricultural systems. This work was conducted to investigate the predictive capability of the Pesticide Root Zone Model (PRZM) and the Aggregate model (AGGR) for the pesticides aldicarb [2-

methyl-2-(methylthio)propionaldehyde O- (methylcarbamoyl)oxime], metolachlor [2-chloro-N-(2-ethyl-6- methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide], and for a bromide tracer. Model predictions were compared with data collected during 1984 to 1987 in the Dougherty Plain area of southwestern Georgia. Field data were used to estimate mean concentrations of pesticide and bromide residues in the soil profile on various dates after application in each of four growing seasons. Both models tended to predict rates of movement of bromide tracer compounds in excess of that observed. For metolachlor, a pesticide with a sorption- partition coefficient that is higher than for other compounds in the study, both models provided reasonably accurate predictions within the upper 30-cm zone. For the pesticide aldicarb, results were more variable. The results suggest that the hydrologic components of both models are more accurate for the upper zones, but they are imprecise in deeper zones, underpredicting vertical dispersion and overpredicting transport velocity. 290 NAL Call. No.: SB249.N6 Theoretical background and validation of CPM, A new cotton simulation model. Sequeira, R.A.; Olson, R.L. Memphis, Tenn. : National Cotton Council of America; 1993. Proceedings - Beltwide Cotton Conferences. p. 543-549; 1993. Meeting held January 10-14, 1993, New Orleans, Louisiana. Includes references. Language: English Descriptors: Cotton; Simulation models; Validity; Theory 291 NAL Call. No.: 292.8 W295 Theoretical study of the significance of nonequilibrium dissolution of nonaqueous phase liquids in subsurface systems. Powers, S.E.; Loureiro, C.O.; Abriola, L.M.; Weber, W.J. Jr Washington, D.C. : American Geophysical Union; 1991 Apr. Water resources research v. 27 (4): p. 463-477; 1991 Apr. Includes references. Language: English Descriptors: Groundwater pollution; Soil pollution; Subsurface layers; Aquifers; Pollutants; Mass transfer; Movement in soil; Mathematical models Abstract: The objective of this work is to assess the potential significance of deviations from local equilibrium for the exchange of mass between residual nonaqueous phase liquids and the aqueous phase in the saturated groundwater zone. A one-dimensional convection-dispersion mass balance equation incorporating a first-order interphase mass transfer rate relationship and temporal changes in blob configuration is used to model this system. Analytical and numerical methods are employed to examine the steady state and transient

behavior of the system under a variety of hypothetical aquifer conditions and pumping remediation schemes. Sensitivity of the model to several parameters including mass transfer coefficient, blob size and shape, and Darcy velocity is explored. Results of the theoretical assessment indicate that nonequilibrium effects could play a significant role in some contamination scenarios, primarily for large blob sizes and relatively high velocities. Design of soil flushing techniques will be impacted by these conclusions. Uncertainty in several parameter values used in this analysis indicate the need for further experimental investigation of this process. 292 NAL Call. No.: HC110.W43T48 1993 Theory, modeling, and experience in the management of nonpoint-source pollution. Russell, Clifford S.; Shogren, Jason F. Boston : Kluwer Academic Publishers,; 1993. xvii, 345 p. : ill., maps ; 24 cm. (Natural resource management and policy). Papers presented at a workshop sponsored by the Association of Environmental and Resource Economists and held at the University of Kentucky, Lexington, KY, in June 1991. Includes bibliographical references. Language: English; English Descriptors: Water; Agricultural pollution; Water quality management 293 NAL Call. No.: 292.8 W295 A three-dimensional field study of solute transport through unsaturated, layered, porous media. 2. Characterization of vertical dispersion. Ellsworth, T.R.; Jury, W.A. Washington, D.C. : American Geophysical Union; 1991 May. Water resources research v. 27 (5): p. 967-981; 1991 May. Includes references. Language: English Descriptors: Transport processes; Vertical movement; Dispersion; Solutes; Soil types; Prediction; Mathematical models; Transformation Abstract: Solute plumes were created in an unsaturated field soil with either flux application or by leaching an initial resident distribution (see Ellsworth et al., this issue). The spatial variance of the plumes initially increased with time between the soil surface and a depth of 2.5 m, within which the soil was a nearly structureless loamy sand. Below this depth, the plumes were observed to compress in the vertical direction as they moved into, and through, a region of subangular blocky structure and loam texture (between 2.5 and 4.0 m depth). As the solute moved below the layer of fine texture, the plume variance again increased with time. Using a transformed advection-dispersion equation description, two constant, field-averaged transport coefficients, V and D zz,

were determined in a scaled coordinate system from the moment equations. These two constant parameters were then used to predict the observed local, or plot scale, transport. Results indicate that the two constant parameters describe transport reasonably well at each plot site and over all sampling depths. 294 NAL Call. No.: 292.8 W295 A three-dimensional field study of solute transport through unsaturated, layered, porous media. I. Methodology, mass recovery, and mean transport. Ellsworth, T.R.; Jury, W.A.; Ernst, F.F.; Shouse, P.J. Washington, D.C. : American Geophysical Union; 1991 May. Water resources research v. 27 (5): p. 951-965; 1991 May. Includes references. Language: English Descriptors: California; Transport processes; Solutes; Soil types; Physicochemical properties; Prediction; Mathematical models Abstract: A field experiment is reported which monitored the three-dimensional movement of cubic solute plumes through an unsaturated, loamy sand soil. The plumes were created with one of two methods, a two-dimensional flux application and an initial resident distribution. Soil coring was used to sample resident concentrations for the three solutes studied. The data were analyzed using the method of moments. In addition to the solute transport experiments, a detailed set of physical properties of the field was obtained by excavating three pits to a depth of 5.0 m and also by taking soil cores throughout the study area. This paper explains the experimental methodology, summarizes the relevant site characteristics, and describes the observed transport based on the zeroth and first order spatial moments. Mass balance varied between 78 and 138%. The field-averaged gravimetric water content and dry bulk density were used to accurately predict the mean vertical plume displacements. The plumes spread relatively little in the horizontal direction. 295 NAL Call. No.: TD420.A1P7 Trace metal soil quality criteria to protect groundwater. Lee, J.; Chen, B.; Allen, H.E.; Huang, C.P.; Sparks, D.L.; Sanders, P. Oxford : Pergamon Press; 1992. Water science and technology : a journal of the International Association on Water Pollution Research and Control v. 26 (9/11): p. 2327-2329; 1992. In the series analytic: Water Quality International '92. Part 5 / edited by M. Suzuki, et.al. Proceedings of the Sixteenth Biennial Conference of the International Association on Water Pollution Research and Control held May 24-30, 1992, Washington, D.C. Language: English

Descriptors: New Jersey; Soil pollution; Pollutants; Standards; Metals; Groundwater pollution; Soil; Adsorption; Soil ph; Mathematical models 296 NAL Call. No.: TD403.G7 Tracer test evaluation of a drainage ditch capture zone. Chambers, L.W.; Bahr, J.M. Dublin, Ohio : Ground Water Pub. Co; 1992 Sep. Ground water v. 30 (5): p. 667-675; 1992 Sep. Includes references. Language: English Descriptors: Wisconsin; Groundwater pollution; Agricultural chemicals; Spread; Prevention; Drainage; Ditches; Tracers; Iodide; Bromide; Tests; Prediction; Capacity; Analytical methods; Models; Movement in soil 297 NAL Call. No.: TD403.G7 Transient and steady-state solute transport through a large unsaturated soil column. Porro, I.; Wierenga, P.J. Dublin, Ohio : Ground Water Pub. Co; 1993 Mar. Ground water v. 31 (2): p. 193-200; 1993 Mar. Includes references. Language: English Descriptors: Soil pollution; Groundwater pollution; Pollutants; Solutes; Movement in soil; Transient flow; Steady flow; Unsaturated flow; Prediction; Models Abstract: The use of steady-state models can sometimes reduce the computational resources and input data required for solution of transient transport problems. A large column experiment was performed to test whether solute transport parameters determined from a steady flow experiment may be used in transient, unsaturated flow and transport model predictions. Tritiated water and bromide were applied at a steady rate to the top of a 0.95 m diameter by 6 m deep soil column containing unsaturated soil. After 10 days, tracers were eliminated from the irrigation water. When the soil moisture content within the column ceased to change, another 10-day pulse of tritiated water and bromide was applied, followed by water without tracers. Transport model parameters were determined through optimization, using breakthrough curves observed at various depths. The tritiated water and bromide pulses lagged behind the wetting front during infiltration into the relatively dry soil. The bromide pulse moved 17-20% faster than the tritiated water pulse, because of anion exclusion. Breakthrough curves for the transient and steady-state experiments were similar. Because the solute fronts lagged significantly behind the moisture fronts, steady-state transport parameters, when used in a fully transient numerical model, fairly described the transport

under transient conditions. 298 NAL Call. No.: 56.9 SO3 Transport in a horizontal flow chamber. Sadeghi, A.M.; Starr, J.L. Madison, Wis. : The Society; 1992 Mar. Soil Science Society of America journal v. 56 (2): p. 600-603; 1992 Mar. Includes references. Language: English Descriptors: Groundwater flow; Horizontal flow; Transport processes; Laboratory methods; Simulation models; Soil water; Soil pore system; Velocity; Hydrodynamic dispersion Abstract: A better understanding is needed of the factors that control the rate of chemicals that move laterally in shallow groundwater within fields to tile lines and drainage ditches and from fields to nearby streams or estuaries. A chamber was designed and used to simulate shallow groundwater flow in the field. The chamber, made of Plexiglas with dimensions 120 by 60 by 60 cm, was filled to a depth of 30 cm with sand. A multiport arrangement of 10-mm-diam. holes on a 5 by 5 cm grid on both end walls of the chamber provided a combination for quite uniform solute application at the inlet side, and allowed sampling simultaneously from all ports at the outlet side. As a first approximation, the flow and transport were assumed to be one dimensional, and a convective-dispersive solute-transport model was applied to the Cl breakthrough data of each of the 50 outlet ports in order to quantify the spatial distribution of the dispersion- coefficient values at the outlet plate. Based on the inconsistency observed between measured and estimated pore- water velocities and dispersion coefficients of each of the 50 outlet ports, it appears that the one-dimensional model is not appropriate to adequately characterize transport parameter in this horizontal flow system. 299 NAL Call. No.: RA1270.P35A1 Transport of a BTX mixture in a groundwater aquifer material. Uchrin, C.G.; Katz, J. New York, N.Y. : Springer-Verlag; 1991 Apr. Bulletin of environmental contamination and toxicology v. 46 (4): p. 534-541; 1991 Apr. Includes references. Language: English Descriptors: New Jersey; Petroleum; Benzene; Toluene; Xylene; Flow; Leaching; Aquifers; Groundwater; Mathematical models 300 NAL Call. No.: 30 AD9 Transport of chemicals through soil: mechanisms, models, and field applications. Jury, W.A.; Fluhler, H.

San Diego, Calif. : Academic Press; 1992. Advances in agronomy v. 47: p. 141-210; 1992. Literature review. Includes references. Language: English Descriptors: Soil chemistry; Movement in soil; Solutes; Transport processes; Literature reviews; Mathematical models 301 NAL Call. No.: QH540.N3 Transport of linearly reactive solutes in porous media. Basic models and concepts. Schweich, D. Berlin, W. Ger. : Springer-Verlag; 1993. NATO ASI series : Series G : Ecological sciences v. 32: p. 221-245; 1993. In the series analytic: Migration and fate of pollutants in soils and subsoils / edited by D. Petruzzelli and F.G. Helfferich. Proceedings of the NATO Advanced Study Institute, May 24-June 5, 1992, Maratea, Italy. Includes references. Language: English Descriptors: Soil pollution; Pollutants; Transport processes; Equations; Mathematical models; Soil water movement; Groundwater flow 302 NAL Call. No.: 56.8 J823 Two models for the leaching of a non-reactive solute to a mole drain. Scotter, D.R.; Heng, L.K.; White, R.E. Oxford : Blackwell Scientific Publications; 1991 Dec. The Journal of soil science v. 42 (4): p. 565-576; 1991 Dec. Includes references. Language: English Descriptors: Mole drainage; Solutes; Losses from soil; Simulation models; Mathematical models; Silt loam soils; Potassium chloride; Chloride; Leaching Abstract: Two models of solute leaching to a mole-pipe drainage system are described. The first model is research- oriented. It simplifies two-dimensional water and solute flow to a mole drain by dividing the soil between the mid-mole plane and the mole into notional compartments. Solute movement between compartments is assumed to occur by convection and mechanical dispersion. Within each compartment a mobile and immobile solute phase is defined, with diffusion occurring between them. Rainfall intensity (over approximately hourly, intervals) and basic soil hydraulic data are needed as inputs. An explicit finite-difference solution to the water and solute mass-balance and flux equations is used. The second simpler model is management-oriented. It uses daily time steps, and assumes the soil solution behaves as if it were a well-mixed system. It requires only-daily rainfall and evaporation data, the drainage coefficient of the mole-pipe system, and the soil

macroporosity as inputs. In both models a source/sink term accounts for additions of solute in rainfall and fertilizer, and extraction by plant uptake. The models were used to simulate leaching, losses of chloride to a mole-pipe drainage system in a silt loam under pasture, following the application of potassium chloride to the soil surface. The first model simulated leaching better immediately after fertilizer application, and during bypass flow, induced by heavy rain. However both models were able to simulate the measured losses over a 2-year period equally well. 303 NAL Call. No.: TC401.W27 Two new characteristic parameters for runoff computation. Leu, J.M.; Liu, C.L. Dordrecht : Kluwer Academic Publishers; 1992. Water resources management v. 6 (1): p. 165-184; 1992. Includes references. Language: English Descriptors: Taiwan; Rain; Runoff; Watersheds; Models 304 NAL Call. No.: 290.9 AM32T Uncertainty analysis of the WEPP soil erosion model. Chasves, H.M.L.; Nearing, M.A. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Nov. Transactions of the ASAE v. 34 (6): p. 2437-2444; 1991 Nov. Includes references. Language: English Descriptors: Water erosion; Prediction; Losses from soil systems; Simulation models Abstract: Predictions from hydrologic and erosion models contain a large degree of uncertainty. The Modified Point Estimate Method (Harr, 1989) used in conjunction with a response surface exploration technique (Brooks, 1958) provides a simple, computationally efficient, and powerful tool for evaluating uncertainty of predictions by natural-resource models. The method allows analysis of models with a large number of input parameters which may be correlated and for which the exact input parameter distribution is unknown. The method was applied to the Water Erosion Prediction Project single rainfall-event erosion model. Sixty treatment combinations were selected to determine WEPP output uncertainties for a wide range of soil, crop, management, topographic, and storm conditions. The levels of the treatment combinations were randomly selected to span the entire factorial space of the 28 WEPP inputs, but with a finite number of treatment combinations. Five WEPP outputs were studied: peak runoff rate, average soil loss, average deposition, sediment yield, and sediment specific surface enrichment ratio. Maximum and average output uncertainties, given by the coefficient of variation, were determined for

each output of the 60 treatments. Maximum coefficients of variation for peak runoff rate, soil loss, sediment yield, and sediment enrichment ratio were 196, 267, 323, and 47%, respectively. Average coefficients of variation for the same set of variables were 65, 99, 106, and 13%, respectively. Coefficient of variation was less for larger runoff and erosion events, which account for a large percentage of the total soil loss at a location over extended time periods. Significant, positive correlations existed between the coefficients of variation of peak runoff average soil loss, and average soil loss and sediment yield, indicating that the uncertainty in average soil loss and in sediment yield may be directly related to the uncertainty in peak runoff rate. 305 NAL Call. No.: 56.8 SO3 Unsaturated hydraulic characteristics of composted agricultural wastes, tuff, and their mixtures. Wallace, R.; Silva, F.F. da; Chen, Y. Baltimore, Md. : Williams & Wilkins; 1992 Jun. Soil science v. 153 (6): p. 434-441; 1992 Jun. Includes references. Language: English Descriptors: Composts; Grape marc; Volcanic ash; Mixtures; Culture media; Pot culture; Unsaturated hydraulic conductivity; Determination; Mathematical models; Soil water retention; Soil water potential; Saturated hydraulic conductivity; Hysteresis; Crop management; Fertilizers; Irrigation 306 NAL Call. No.: 56.9 SO3 Urea transformations in flooded soil columns. II. Derivation of model and implications to ammonia volatilization. Bouldin, D.R.; Hongprayoon, C.; Lindau, C.W.; Patrick, W.H. Jr Madison, Wis. : The Society; 1991 Jul. Soil Science Society of America journal v. 55 (4): p. 1135-1142; 1991 Jul. Includes references. Language: English Descriptors: Oryza sativa; Silt loam soils; Urea; Transport processes; Volatilization; Ammonia; Losses from soil systems; Diffusion; Hydrolysis; Sorption; Ammonium nitrogen; Diffusivity; Mathematical models; Soil management; Incorporation; Depth; Ph; Temperature; Flooded rice; Paddy soils; Laboratory methods Abstract: Ammonia volatilization from rice (Oryza sativa L.) paddies following urea application reduces the effectiveness of the urea-N. The objectives of this study were to: (i) derive, for flooded soils, a model describing hydrolysis and diffusion of urea and diffusion of ammoniacal N; (ii) derive the necessary parameters from experimental data, and (iii) use the model to study implications of hydrolysis/transport sport

parameters and management variables to NH3 volatilization. The parameters are diffusion coefficients of urea and NH4, in soil hydrolysis coefficients of urea in the soil and overlying floodwater, and the sorption coefficient for NH4 on the soil. The effects on potential for NH3 volatilization of variation in these parameters and the management factors of depth of flood water and depth of fertilizer incorporation were calculated. The results illustrate that urea-hydrolysis rates in the floodwater and soil are the most important factors influencing the potential for NH3 volatilization. If urea- hydrolysis rates are very high, incorporation and shallow floodwater are the indicated management while, with low hydrolysis rates, deep floodwater and no incorporation are the indicated management. 307 NAL Call. No.: 56.8 J822 Use of a geographic information system for selection of sites for land application of sewage waste. Hendrix, W.G.; Buckley, D.J.A. Ankeny, Iowa : Soil and Water Conservation Society of America; 1992 May. Journal of soil and water conservation v. 47 (3): p. 271-275; 1992 May. Includes references. Language: English Descriptors: Vermont; Agricultural land; Forests; Land types; Sewage effluent; Sewage effluent disposal; Waste disposal sites; Selection methods; Information systems; Geography; Computer techniques; Site factors; Soil variability; Soil physical properties; Land use; Topography; Social values; Environmental legislation; Models 308 NAL Call. No.: GB701.W375 no.90-4140 Use of a geographic information system to assess risk to ground-water quality at public-supply wells, Cape Cod, Massachusetts. Olimpio, Julio C. Massachusetts, Division of Water Pollution Control, Geological Survey (U.S.) Boston, Mass. : U.S. Dept. of the Interior, U.S. Geological Survey ; Denver, CO : Books and Open-File Reports Section [distributor],; 1991; I 19.42/4:90-4140. v, 35, 10 p. : ill., maps (some col.) ; 28 cm. (Water- resources investigations report ; 90-4140). Shipping list no.: 91-790-P. Includes bibliographical references (p. 35). Language: English Descriptors: Water quality; Geographic information systems; Water, Underground 309 NAL Call. No.: QH545.A1E58 Use of gleams to predict insecticide losses from pine seed orchards. Nutter, W.L.; Knisel, W.G. Jr; Bush, P.B.; Taylor, J.W.

Tarrytown, Y. : Pergamon Press; 1993 Mar. Environmental toxicology and chemistry v. 12 (3): p. 441-452; 1993 Mar. Paper presented at the "Symposium on Pesticides in Forest Management, 11th Annual Meeting of the Society of Environmental Toxicology and Chemistry," November 11-15, 1990, Arlington, Virginia. Includes references. Language: English Descriptors: Southern states of U.S.A.; Carbofuran; Azinphos- methyl; Fenvalerate; Permethrin; Leaching; Groundwater; Runoff; Vertical movement; Surface water; Seed orchards; Simulation models; Prediction 310 NAL Call. No.: S671.A66 The use of graphics to present the results of erosion models. Bingner, R.L. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Mar. Applied engineering in agriculture v. 7 (2): p. 193-197; 1991 Mar. Includes references. Language: English Descriptors: Erosion; Models; Watersheds; Computer software; Graphic arts; Runoff Abstract: This study shows how graphical representations of a watershed system can be used to analyze the runoff and sediment yield. Combining output data from an erosion model, such as runoff, sediment yield, and particle size distribution of the eroded sediment, onto a single screen on a computer monitor, permits immediate analysis as a rainfall event occurs. This study shows how the erosion models CREAMS and ANSWERS can be modified for simulations on small and large watersheds, using graphics to enhance the results. 311 NAL Call. No.: SB610.W39 Use of modeling in developing label restrictions for agricultural chemicals. Jones, R.L. Champaign, Ill. : The Society; 1992 Jul. Weed technology : a journal of the Weed Science Society of America v. 6 (3): p. 683-687; 1992 Jul. Paper presented at a Symposium on the, "Role of Modeling in Regulatory Affairs," at the Weed Science Society of America, February 4, 1991, Louisville, Kentucky. Includes references. Language: English Descriptors: Agricultural chemicals; Pesticides; Simulation models; Regulations; Labeling; Groundwater; Drinking water; Water quality 312 NAL Call. No.: 60.18 J82 Use of stochastically generated weather records with rangeland

simulation models. Wight, J.R.; Hanson, C.L. Denver, Colo. : Society for Range Management; 1991 May. Journal of range management v. 44 (3): p. 282-285; 1991 May. Includes references. Language: English Descriptors: Rangelands; Herbage; Crop yield; Prediction; Simulation models; Weather data; Runoff; Precipitation; Air temperature; Solar radiation; Stochastic models; Yield forecasting; Hydrological data Abstract: We compared long-term historical and stochastically generated weather records in terms of their statistical attributes and effects on herbage yield and runoff forecasts calculated from model simulations. The historical and synthetic air temperature and solar radiation records were in good agreement in terms of monthly means and extremes. The synthetic precipitation record failed to simulate extreme precipitation events which significantly reduced forecasted runoff values. Yield forecasts were similar using either historical or synthetic weather records. 313 NAL Call. No.: HC79.E5E5 Use of wetlands for water quality improvement under USEPA Region V Clean Lakes Programs. Landers, J.C.; Knuth, B.A. New York, N.Y. : Springer-Verlag; 1991 Mar. Environmental management v. 15 (2): p. 151-162; 1991 Mar. Includes references. Language: English Descriptors: Minnesota; Wisconsin; Indiana; Wetlands; Lakes; Water quality; Environmental protection; Runoff water; Land management; Program evaluation; Models; Land diversion; Federal programs 314 NAL Call. No.: SD421.37.C6 1991 Using a GIS to document relationships between disturbance and sedimentation following salvage logging. Wells, W.G. II; Napoleon, E.J.; Wohlgemuth, P.M. Bethesda, Md. : Society of American Foresters; 1991. Proceedings of the 11th Conference on Fire and Forest Meteorology, April 16-19, 1991, Missoula, Montana / sponsored by the Society of American Foresters and American Meteorological Soc. ; editors, P.L. Andrews and D.F. Potts. p. 405-411; 1991. This record corrects IND 92025711 which was entered incorrectly under call number SD143.S64. Includes references. Language: English Descriptors: California; Salvage felling and logging; Erosion;

Sediment 315 NAL Call. No.: 60.18 UN33 Using computer situations to predict the fate and environmental impact of applied pesticides. Franke, K.J. Far Hills, N.J. : United States Golf Association; 1992 Mar. USGA Green Section record v. 30 (2): p. 17-21; 1992 Mar. Language: English Descriptors: Lawns and turf; Golf courses; Pesticides; Integrated pest management; Environmental impact; Computer simulation 316 NAL Call. No.: 10 OU8 Using crop models for sustainability and environmental quality assessment. Singh, U.; Thornton, P.K. Oxon : C.A.B. International; 1992. Outlook on agriculture v. 21 (3): p. 209-218; 1992. Includes references. Language: English Descriptors: Crop production; Environmental impact; Leaching; Nitrogen fertilizers; Pollution; Simulation models; Sustainability 317 NAL Call. No.: 56.9 SO32 Using geographic information systems in a well permitting program. Myhre, B.E.; Shih, S.F. S.l. : The Society; 1991. Proceedings - Soil and Crop Science Society of Florida v. 50: p. 102-105; 1991. Paper presented at the "Symposium on Reality of Sustainable Agriculture in Florida, September 26-28, 1990, Daytona Beach, FLorida. Includes references. Language: English Descriptors: Florida; Groundwater; Water quality; Wells; Geographical distribution 318 NAL Call. No.: 56.9 SO32 Using landsat data and geographic information system for wetland assessment in water-quality management. Still, D.A.; Shih, S.F. S.l. : The Society; 1991. Proceedings - Soil and Crop Science Society of Florida v. 50: p. 98-102; 1991. Paper presented at the "Symposium on Reality of Sustainable Agriculture in Florida, September 26-28, 1990, Daytona Beach, FLorida. Includes references. Language: English

Descriptors: Florida; Wetlands; Water quality; Assessment; Landsat 319 NAL Call. No.: 292.9 AM34 Using soil texture to estimate saturated hydraulic conductivity and the impact on rainfall-runoff simulations. Loague, K. Bethesda, Md. : American Water Resources Association; 1992 Jul. Water resources bulletin v. 28 (4): p. 687-693; 1992 Jul. Includes references. Language: English Descriptors: Rangelands; Rangeland soils; Soil texture; Saturated hydraulic conductivity; Infiltration; Rain; Runoff; Simulation models; Mathematical models Abstract: In this paper a new set of soil texture data is used to estimate the spatial distribution or saturated hydraulic conductivity values for a small rangeland catchment. The estimates of conductivity are used to re-excite and re- evaluate a quasi-physically based rainfall-runoff model. The performance or the model is significantly reduced with conductivity estimates gleaned from soil texture data rather than the infiltration data used in our previous efforts. 320 NAL Call. No.: 290.9 AM32T Using the ANSWERS model to predict runoff and soil loss in southwestern Quebec. Montas, H.J.; Madramootoo, C.A. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Jul. Transactions of the ASAE v. 34 (4): p. 1754-1762; 1991 Jul. Includes references. Language: English Descriptors: Quebec; Losses from soil systems; Runoff; Sediment; Computer simulation; Erosion; Watersheds Abstract: The distributed parameter model ANSWERS was used to predict runoff and soil loss for two small agricultural watersheds in southwestern Quebec. Runoff predictions were compared for 24 observed events. Peak flow was generally underpredicted and time to peak was overpredicted. A seasonal adjustment of infiltration parameters was derived to account for crusting and sealing of the soils in the spring and fall. Runoff predictions with adjusted parameters were better than those with measured parameters. Predictions of sediment concentration and yield, with adjusted infiltration parameters, were compared with seven observed storm events. ANSWERS underpredicted sediment yield for all events. 321 NAL Call. No.: 290.9 AM32T

Validating GLEAMS with pesticide field data on a Clermont silt loam soil. Sichani, S.A.; Engel, B.A.; Monke, E.J.; Eigel, J.D.; Kladivko, E.J. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Jul. Transactions of the ASAE v. 34 (4): p. 1732-1737; 1991 Jul. Includes references. Language: English Descriptors: Indiana; Alachlor; Atrazine; Cyanazine; Carbofuran; Chlorpyrifos; Groundwater; Leaching; Simulation models; Water pollution Abstract: The GLEAMS (Groundwater Loading Effects of Agricultural Management Systems) model was used to simulate the appearances of pesticides in outflow of an experimental drainage field at the South East Purdue Agricultural Center (SEPAC) in southeastern Indiana. This article presents the comparison of simulated and observed loading of Alachlor, Atrazine, Cyanazine, Carbofuran, and Chlorpyrifos in tile outflows for 1985 through 1989. Me results of the simulation were close to field observations for total masses of pesticides leached from the root zone and for the overall timing of pesticide appearance in tile flows. However, the simulation of the watershed did not predict the observed arrival of pesticides in the drain during the first storm event after pesticide application. To compare the simulated results from on-site weather data and the data from nearby locations, long-term mean monthly solar radiation data for SEPAC and Indianapolis, Indiana were evaluated. 322 NAL Call. No.: FICHE S-72 Validation of WEPP 91.2 with erosion plot data. Kramer, L.A.; Alberts, E.E.; Ghidey, F. St. Joseph, Mich. : The Society; 1991. American Society of Agricultural Engineers (Microfiche collection) (fiche no. 91-2079): 16 p.; 1991. Paper presented at the 1991 Summer Meeting of the American Society of Agricultural Engineers held June 23-26, 1991, Albuquerque, New Mexico. Includes references. Language: English Descriptors: Water erosion; Prediction; Simulation models; Runoff; Losses from soil systems; Experimental plots; Tillage; Zea mays; Regression analysis 323 NAL Call. No.: 292.8 W295 Vapor transport in unsaturated soil columns: implications for vapor extraction. Gierke, J.S.; Hutzler, N.J.; McKenzie, D.B. Washington, D.C. : American Geophysical Union; 1992 Feb. Water resources research v. 28 (2): p. 323-335; 1992 Feb. Includes references. Language: English

Descriptors: Soil pollution; Contaminants; Toluene; Methane; Vapor; Extraction; Transport processes; Sand; Aggregates; Mathematical models Abstract: A mathematical model was derived to examine the impact of gas advection, gas diffusion, gas-water mass transfer, gas-water partitioning, sorption, and intraaggregate diffusion on subsurface movement of organic vapors. Laboratory experiments were performed to determine the validity of the model and to investigate the impact of the various mechanisms on vapor transport, Columns were packed with a uniform Ottawa sand and an aggregated porous soil material (APSM) to compare transport in different soil structures. Toluene vapor transport was observed in the sand under dry and wet (27% water saturation) conditions. The experiments with the APSM were performed dry and at 67% water saturation. in all the sand and the dry APSM experiments, gas advection and diffusion had the greatest impact. In a wet APSM experiment, intraaggregate (liquid) diffusion was also important to consider for gas velocities greater than approximately 0.05 cm s-1. For both soil materials, sorption of toluene vapors occurred for dry conditions, while vapor sorption was negligible when liquid water was present. These findings imply that vapor extraction performance in moist, aggregated soils will be affected by nonequilibrium transport. Therefore models that are developed for predicting the complete removal of contaminants by vapor extraction must account for nonequilibrium. 324 NAL Call. No.: 290.9 AM32T Variability of optimized parameter estimates based on observed record length. Allred, B.; Haan, C.T. St. Joseph, Mich. : American Society of Agricultural Engineers; 1991 Nov. Transactions of the ASAE v. 34 (6): p. 2421-2426. maps; 1991 Nov. Includes references. Language: English Descriptors: Oklahoma; Arkansas; Hydrology; Rain; Runoff; Stream flow; Watersheds; Mathematical models Abstract: The variability in parameter estimates for a hydrologic model as a function of the number of years of data available for estimating the parameters was investigated. A 25-year record on Spavinaw Creek in Oklahoma and Arkansas was divided into 25 one-year, 12 two-year, and 5 five-year records. Each period was used for parameter estimation. Two objective functions, one based on absolute errors and one based on error sum of squares, were used. Mean parameter values exhibited greater than expected variability, and variances in estimated parameters did not decrease as expected as the number of years used for parameter estimation increased from one to five years. One year was found to dominate one of the estimated model parameters for any record length that included that particular year. Significant differences between

parameter values based on the two objective functions were found only for one parameter based on one-year optimizations. 325 NAL Call. No.: 448.3 AP5 VIRTUS, a model of virus transport in unsaturated soils. Yates, M.V.; Ouyang, Y. Washington, D.C. : American Society for Microbiology; 1992 May. Applied and environmental microbiology v. 58 (5): p. 1609-1616; 1992 May. Includes references. Language: English Descriptors: Groundwater; Viruses; Transport processes; Soil water content; Soil water regimes; Movement in soil; Inactivation; Soil temperature; Pollutants; Models Abstract: As a result of the recently proposed mandatory groundwater disinfection requirements to inactivate viruses in potable water supplies, there has been increasing interest in virus fate and transport in the subsurface. Several models have been developed to predict the fate of viruses in groundwater, but few include transport in the unsaturated zone and all require a constant virus inactivation rate. These are serious limitations in the models, as it has been well documented that considerable virus removal occurs in the unsaturated zone and that the inactivation rate of viruses is dependent on environmental conditions. The purpose of this research was to develop a predictive model of virus fate and transport in unsaturated soils that allows the virus inactivation rate to vary on the basis of changes in soil temperature. The model was developed on the basis of the law of mass conservation of a contaminant in porous media and couples the flows of water, viruses, and heat through the soil. Model predictions were compared with measured data of virus transport in laboratory column studies and, with the exception of one point, were within the 95% confidence limits of the measured concentrations. The model should be a useful tool for anyone wishing to estimate the number of viruses entering groundwater after traveling through the soil from a contamination source. In addition, model simulations were performed to identify parameters that have a large effect on the results. This information can be used to help design experiments so that important variables are measured accurately. 326 NAL Call. No.: 292.8 J82 Water balance and soil moisture dynamics of field plots with barley and grass ley. Johnsson, H.; Hansson, P.E. Amsterdam : Elsevier Scientific Publishers, B.V.; 1991 Dec. Journal of hydrology v. 129 (1/4): p. 149-173; 1991 Dec. Includes references. Language: English

Descriptors: Sweden; Hordeum vulgare; Festuca pratensis; Leys; Arable land; Nitrogen fertilizers; Soil water; Soil water balance; Evapotranspiration; Evaporation; Transpiration; Soil physical properties; Plant development; Meteorological factors; Drainage; Runoff; Precipitation; Simulation; Physical models Abstract: A physically based soilwater and heat model was used to estimate the water balance of an arable field in central Sweden for each of three different crop covers (barley with and without N fertilization and grass ley). Annual water balances were calculated for each year from 1981 to 1985. On- site measurements of soil physical properties, meteorological variables and plant development were used as input to the model. Simulated soil frost, snow cover, soilwater contents, soilwater tensions and relative differences in simulated drainage between treatments were in agreement with the corresponding measured values. In the simulation, surface runoff (70 mm year-1 in all treatments) mainly occurred during snowmelt periods and accounted for much of the variation in the total runoff estimate. Annual mean precipitation amounted to 610 mm year-1, whereas average evapotranspiration was calculated to be 320, 360 and 435 mm year-1 in barley without N fertilization, barley with N fertilization and grass ley, respectively. Soil evaporation accounted for 60, 43 and 23% whereas evaporation of intercepted water accounted for 5, 12 and 19% of the total evapotranspiration, respectively. Drainage estimates amounted to 205, 170 and 110 mm year-1. 327 NAL Call. No.: 56.8 J822 Water balance components in the Georgia Coastal Plain: a GLEAMS model validation and simulation. Knisel, W.G.; Leonard, R.A.; Davis, F.M.; Sheridan, J.M. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Nov. Journal of soil and water conservation v. 46 (6): p. 450-456; 1991 Nov. Includes references. Language: English Descriptors: Georgia; Watersheds; Rain; Runoff; Subsurface drainage; Water balance; Simulation models; Validity 328 NAL Call. No.: 280.8 J822 Water markets and water quality. Weinberg, M.; Kling, C.L.; Wilen, J.E. Ames, Iowa : American Agricultural Economics Association; 1993 May. American journal of agricultural economics v. 75 (2): p. 278-291; 1993 May. Includes references. Language: English Descriptors: U.S.A.; Water quality; Irrigation water; Markets; Water use efficiency; Water allocation; Farm management; Decision making; Drainage; Simulation models; Water policy

Abstract: In addition to improving the allocative efficiency of water use, water markets may reduce irrigation-related water quality problems. This potential benefit is examined with a nonlinear programming model developed to simulate agricultural decision-making in a drainage problem area in California's San Joaquin Valley. Results indicate that a 30% drainage goal is achievable through improvements in irrigation practices and changes in cropping patterns induced by a water market. Although water markets will not generally achieve a least-cost solution, they may be a practical alternative to economically efficient, but informationally intensive, environmental policies such as Pigouvian taxes. 329 NAL Call. No.: TD419.5.W365 1991 Water pollution modelling, measuring, and prediction. Brebbia, C. A.; Wrobel, L. C. International Conference on Water Pollution: Modelling, Measuring, and Prediction 1st : 1991 : Southampton, England. Southampton ; Boston : Computational Mechanics Pub. ; London ; New York : Elsevier Applied Science,; 1991. 748 p. : ill. ; 24 cm. "Contains the edited versions of some of the papers presented at the First International Conference on Water Pollution: Modelling, Measuring and Prediction"--P. 4 of cover. Includes bibliographical references and index. Language: English Descriptors: Water; Water quality; Sewage 330 NAL Call. No.: 302.8 T162 Water quality and biological investigation of the lower Cape Fear River Basin. Kreutzberger, W.A.; Wakild, C.R. Norcross, Ga. : The Technical Association of the Pulp and Paper Industry; 1993 Jul. Tappi journal v. 76 (7): p. 169-177; 1993 Jul. Includes references. Language: English Descriptors: North Carolina; Pulp and paper industry; Pulp mill effluent; Water quality; Biochemical oxygen demand; Models; Rivers 331 NAL Call. No.: TD172.J6 Water quality modeling in distribution systems. Clark, R.M. New York, N.Y. : Marcel Dekker; 1992 Jul. Journal of environmental science and health : Part A : Environmental science and engineering v. 27 (5): p. 1329-1366; 1992 Jul. Includes references. Language: English Descriptors: U.S.A.; Drinking water; Water quality;

Deterioration; Quality standards; Law enforcement; Environmental protection; Public agencies; Water distribution; Systems; Health hazards 332 NAL Call. No.: TD482.W38 1991 Water quality modeling in distribution systems conference proceedings, February 4-5, 1991, Cincinnati, Ohio.. Proceedings, water quality modeling in distribution systems AWWA Research Foundation, United States, Environmental Protection Agency Denver, Colo. : The Foundation,; 1991. viii, 469 p. : ill., maps ; 23 cm. Cover title: Proceedings, water quality modeling in distribution systems. Includes bibliographical references and index. Language: English Descriptors: Water quality; Water 333 NAL Call. No.: TD370.W3957 1992 Water quality modelling. Falconer, R. A. Institution of Water and Environmental Management Aldershot, Hants, England ; Brookfield, Vt., USA : Ashgate,; 1992. xii, 139 p. : ill. ; 24 cm. Published in association with the Institution of Water and Environmental Management. Papers from a one day symposium given by the IWEM and held in Harrogate on 11/13/91. Includes bibliographical references. Language: English Descriptors: Water quality 334 NAL Call. No.: 290.9 AM32T Water table management practice effects on water quality. Wright, J.A.; Shirmohammadi, A.; Magette, W.L.; Fouss, J.L.; Bengtson, R.L.; Parsons, J.E. St. Joseph, Mich. : American Society of Agricultural Engineers; 1992 May. Transactions of the ASAE v. 35 (3): p. 823-831; 1992 May. Includes references. Language: English Descriptors: Water management; Water quality; Water table; Drainage; Hydrology; Simulation models; Subsurface irrigation Abstract: Impacts of water table management (WTM) practices on water quality were modeled using a linked version of CREAMS and DRAINMOD (Parsons and Skaggs, 1988). The CREAMS denitrification component and the linked DRAINMOD-CREAMS model were modified to simulate daily hydrology (runoff, infiltration, evaporation, and soil moisture content), erosion, and nutrient processes for different WTM conditions. Measured data from Baton Rouge, Louisiana, were used to validate the linked model, and then controlled drainage-

subirrigation (CD-SI) was simulated to investigate the effects of different WTM systems on runoff, erosion, and nitrogen losses. Results of the study indicated that the linked models performed better than the original CREAMS model in predicting runoff, infiltration, soil moisture content, and erosion, and that the modified linked model performed better than both CREAMS and the original linked model in predicting nitrogen losses from the study site. Results also showed that the CD-SI system simulated by the modified DRAINMOD-CREAMS model predicted increased denitrification and lowered nitrate leaching, unlike the original version. This study concluded that the CD-SI system may be used as a BMP to reduce nitrogen leaching to shallow groundwater systems for areas with high water table conditions. 335 NAL Call. No.: 292.8 J82 Water vapor transfer beneath bare soil where evaporation is influenced by a turbulent surface wind. Ishihara, Y.; Shimojima, E.; Harada, H. Amsterdam : Elsevier Scientific Publishers, B.V.; 1992 Feb. Journal of hydrology v. 131 (1/4): p. 63-104; 1992 Feb. Includes references. Language: English Descriptors: Soil types; Subsurface layers; Water vapor; Evaporation; Transport processes; Diffusion; Diffusivity; Wind; Turbulent flow; Air flow; Particle size; Mathematical models Abstract: A laboratory experiment on evaporation in various porous material layers was undertaken by applying a turbulent air flow to the exposed surface, to investigate the mechanism of the water vapor transport beneath a bare ground surface influenced by a turbulent surface wind. Variation of air pressure within these layers was also measured. Based on a physical model of water vapor transfer, an observed function decribing bulk resistance for water vapor transfer with evaporating front depth was investigated, using an observed power spectrum of the pore-air pressure. The model is based on the so-called turbulent mixing theory. The following conclusions were reached. When porous material layers are of low permeability such as fine sand, water vapor transfer under the exposed surface occurs by molecular diffusion as well as by turbulent diffusion caused by variation of the pore-air pressure due to the turbulent surface wind (P-type). The surface turbulence significantly affects the transport just beneath the surface. Turbulent diffusivity near the surface is determined by horizontal and vertical fluctuating components of the pore-air pressure, but with increasing depth is driven only by the vertical component. When the porous material layer is more permeable, water vapor transfer in this layer is analogous to that within a vegetation canopy (F-type), so that turbulent diffusivity decays exponentially with depth. The turbulent diffusivity is a function of the mixing length. The mixing length for F-type was of the order of the particle

size. For P-type the mixing length ranged from the particle size to ten times larger. 336 NAL Call. No.: 56.8 J822 WEPP: a new generation of erosion prediction technology. Laflen, J.M.; Lane, L.J.; Foster, G.R. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Jan. Journal of soil and water conservation v. 46 (1): p. 34-38; 1991 Jan. Includes references. Language: English Descriptors: Erosion; Universal soil loss equation; Prediction; Water erosion 337 NAL Call. No.: 56.8 J822 WEPP: soil erodibility experiments for rangeland and cropland soils. Laflen, J.M.; Elliot, W.J.; Simanton, J.R.; Holzhey, C.S.; Kohl, K.D. Ankeny, Iowa : Soil and Water Conservation Society of America; 1991 Jan. Journal of soil and water conservation v. 46 (1): p. 39-44; 1991 Jan. Includes references. Language: English Descriptors: Water erosion; Prediction; Rangelands; Equations; Erodibility; Rill erosion; Crops; Soil # # # Author Index Abriola, L.M. 291 Adams, R.M. 206 Addiscott, T.M. 233 Adelman, D. 191 Adrian, D.D. 210 Aharoni, C. 127 Ahern, Jack 129 Ahlfeld, D.P. 88 Ahuja, L.R. 22 Alberts, E.E. 322 Alemi, M.H. 168 Allen, G. 114 Allen, H.E. 295 Allen, P.M. 28 Allen, Roderick L. 227 Allred, B. 324 Altafin, I. 137 Amacher, G. 231 Ammentorp, H.C. 157 Antle, J.M. 215 Arnold, J.A. 196, 197 Arnold, J.G. 19, 28 Ashraf, M.S. 167

Asmussen, L.E. 277 Aubry, B.F. 62 Avila, A. 246 AWWA Research Foundation, United States, Environmental Protection Agency 332 Aylmore, L.A.G. 152 Bach, L.B. 266 Bahr, J.M. 296 Baker, D.E. 258 Banks, P.A. 27 Bar-Yosef, B. 91 Barnes, B.B. 22 Barnes, N.L. 106 Barrington, S.F. 78 Barry, D.A. 84 Batie, S.S. 116, 135 Baumer, G.M. 272 Beck, R.M. 111 Behl, E. 30 Behrendt, H. 214 Ben-Asher, J. 209 Bengtson, R.L. 179, 334 Benson, V.W. 194 Berg, W.A. 248 Bergstrom, L. 178 Berisford, Y.C. 175 Bernado, D.J. 68 Bernhard, C. 192 Bernhardt, G. 28 Beven, K.J. 71 Bhargava, D.S. 65 Billett, M.F. 224 Bingner, R.L. 226, 310 Black, A.S. 222 Blackburn, W.H. 34, 242 Blau, G.E. 237 Bloom, S.A. 85 Bode, L.E. 211 Boekhold, A.E. 134, 244 Boesen, C. 193 Boesten, J.J.T.I. 63, 171, 252 Bogardi, I. 142 Bogusch, H.C. 194 Borah, A. 113 Borah, D.K. 167 Bottcher, A.B. 95, 223 Bouldin, D.R. 306 Bouma, J. 148 Bouton, M. 273 Bowen, W.T. 81 Bradbury, N.J. 216 Braden, J.B. 115 Bradford, J.M. 13 Bras, R.L. 42, 125 Brebbia, C. A. 329 Brichford, S.L. 197 Britt, J.K. 143

Brooke, D. 47 Brooke, D.N. 146 Brusseau, M.L. 170 Brusven, M.A. 23 Buchter, B. 173 Buckley, D.J.A. 307 Burgoa, B. 85 Bush, P.B. 27, 89, 175, 309 Cabe, R. 232 Cabral, M.C. 125 Caldwell, D.E. 43 Campbell, K.L. 95 Capalbo, S.M. 215 Carbiener, R. 192 Carlson, C.G. 212 Carsel, R.F. 40, 48 Carsky, R.J. 81 Cary, Lawrence E. 286 Centner, T.J. 230 Chambers, L.W. 296 Chang, A.C. 74 Chasves, H.M.L. 304 Chen, B. 295 Chen, C. 261, 262 Chen, J.S. 85 Chen, W. 283 Chen, Y. 305 Christensen, T.H. 157 Chung, G.Y. 39 Chung, S.O. 80 Clark, R.M. 331 Cloots, A.R. 192 Coffey, S.W. 196, 197 Cohen, S.Z. 106 Coleman, G.A. 248 Comfort, S.D. 41, 288 Cooke, L. 29 Cooley, K.R. 238 Cooper, A.B. 223 Corapcioglu, M.Y. 188 Corradini, C. 162 Corwin, D.L. 98 Cresser, M.S. 224 Cubillo, F. 236 Curtis, B. 191 Dane, J.H. 58, 140, 182, 267 Daniel, T.C. 46, 153, 219 Darby, R.J. 233 Darrah, P.R. 149, 150 Davis, F.M. 213, 327 Day, R.L. 272 DeCoursey, D.G. 22 Deer, H.M. 20 Deizman, M.M. 156 Delong, M.D. 23 Destouni, G. 8, 59, 225, 276 Deverel, S.J. 249

Dhawan, S. 155 Dickinson, W.T. 77, 117 Diebel, P.L. 116, 135 Dik, P.E. 177, 178 Dillard, A.L. 32 Dillworth, M.E. 24 Dkstein, L. 142 Donigian, Anthony S. 166 Dowd, J.F. 175 Duckstein, L. 185, 234 Dudley, L.M. 158, 243 Dunne, T. 62 Dunnivant, F.M. 26 Durborow, T.E. 106 Dwinell, S.E. 143 Edwards, D.R. 46, 219 Ehteshami, M. 20 Eigel, J.D. 321 Ekholm, P. 79 El-Attar, H.A. 288 Elliot, W.J. 82, 337 Elliott, R.L. 68, 180 Ellsworth, T.R. 293, 294 Eltahir, E.A.B. 42 Engel, B.A. 321 Engel, Bernard A. 9 Engesgaard, P. 100 Entekhabi, D. 125 Environmental Research Laboratory (Athens, Ga.) 166 Erickson, L.E. 155 Ernst, F.F. 294 Espeby, B. 37 Euw, E.L. von 117 Fabos, Julius Gy 129 Falconer, R. A. 109, 333 Fan, L.T. 155 Farquhar, G.J. 203 Feng, J.S. 96, 283 Fermanich, K.J. 153 Ferrandino, F.J. 67 Finke, P.A. 148 Finkner, S.C. 110 Fio, J.L. 249 Fisher, A.C. 120 Flanagan, D.C. 12 Flanagan, M. 190 Florida Marine Research Institute, Florida Office of Coastal Management 139 Fluhler, H. 300 Focazio, Michael J. 50 Foltz, J.C. 87 Fong, F.K. 289 Fontaine, D.D. 237 Fontaine, T.D. 86 Foster, G.R. 336 Fouss, J.L. 179, 334 Franke, K.J. 315

Froehlicher, R. 192 Fujii, R. 249 Gaber, H.M. 288 Gale, J.A. 196, 197 Gambolati, G. 198 Ganoulis, J. 235 Garbrecht, J. 64 Garrote, L. 125 Gaston, L.A. 221 Gel'fan, A.N. 53 Geleta, S. 68, 180 Geological Survey (U.S.) 31 Geological Survey (U.S.),California Regional Water Quality Control Board--Colorado River Basin Region 75 Geological Survey (U.S.),Hampton Roads Planning District Commission (Va.),Virginia Water Control Board 50 Gerke, H.H. 51 Gerritse, R.G. 152 Ghidey, F. 322 Gierke, J.S. 323 Gilley, J.E. 110 Glaser, P.H. 111 Glendinning, P.J. 146 Goh, K.M. 200, 201 Goldhamer, D.A. 168 Goodrich, D.C. 126 Goolsby, D.A. 60 Goss, D. 194 Goss, D.W. 245 Graham, D.N. 203 Graney, R.L. 25 Gray, W.G. 44 Green, R.E. 76, 274 Griggs, R.H. 180 Grismer, M.E. 52 Grunblatt, J. 103 Gutema, Y. 147 Guy, B.T. 77 Haan, C.T. 14, 113, 187, 324 Habaieb, H. 36 Haddad, Kenneth D. 139 Halliday, S.L. 16 Halstead, J.M. 116 Hamlett, J.M. 272 Hammers, W.E. 229 Hanemann, W.M. 120 Hanks, R.J. 158 Hansen, J.A. 1, 254 Hanson, C.L. 238, 312 Hansson, P.E. 326 Harada, H. 335 Harbor, J. 285 Harmsen, K. 133 Harper, J.K. 4 Harwell, J.H. 90 Hauser, V.L. 241 Havens, P.L. 237

Havis, R.N. 210 Hayashi, Y. 49 Hayot, C. 204, 205 Head, K.L. 142 Heatwole, C.D. 116, 135, 284 Hendrix, W.G. 307 Hendry, M.J. 43 Heng, L.K. 302 Herricks, E.E. 115 Herriges, J.A. 232 Hill, R.W. 20 Hills, R.G. 130, 247 Hino, M. 199 Hinz, C. 173 Hipp, B.W. 92 Hoag, D.L. 38 Holloway, D. 256 Holzhey, C.S. 337 Hongprayoon, C. 306 Hornsby, A.G. 38, 263 Host-Madsen, J. 128 Hostetler, J. 231 Huang, C.H. 13 Huang, C.P. 295 Huang, L.Q. 67, 270 Huber, Wayne C. 166 Hudson, D.B. 130, 247 Humborg, G. 209 Hummel, J.W. 82 Hummel, P.R. 40, 48 Hutzler, N.J. 323 Imhoff, J.C. 40, 48 Inskeep, W.P. 41, 288 Institution of Water and Environmental Management 333 Ishiguro, M. 268, 269 Ishihara, Y. 335 Islam, M.N. 124 Jabro, J.D. 258 Jacobsen, O.H. 136 Jakeman, A.J. 18 Jakubauskas, M.E. 24 James, A. 122 Jansson, P.E. 177 Jardine, P.M. 26 Jarvis, N.J. 177, 178 Jaynes, D.B. 94 Jennings, G.D. 196, 197 Jensen, K.H. 128 Jessup, R.E. 170 Jian, L.R. 108 Johnson, P.A. 216 Johnson, R.C. 11 Johnson, S.L. 206 Johnsson, H. 279, 326 Jones, J.W. 81 Jones, O.R. 241 Jones, Philip Edward James, 83

Jones, R.E. 27 Jones, R.L. 311 Jurinak, J.J. 243 Jury, W.A. 132, 293, 294, 300 Kamari, J. 79 Kamra, S.K. 250, 251 Kanda, M. 199 Kandil, H. 163 Katz, J. 299 Kawanishi, T. 49 Keefer, T.O. 126 Keeler, A.G. 120 Kelly, W.E. 191 Kenimer, A.L. 211 Kihou, N. 49 Kim, C.S. 231 Kinouchi, T. 199 Kipp, K.L. 100 Kirk, G.J.D. 169 Kirkland, M.R. 247 Kittle, J.L. Jr 40, 48 Kladivko, E.J. 321 Klein, M. 10 Kleveno, J.J. 76 Kling, C.L. 328 Knisel, W.G. 213, 327 Knisel, W.G. Jr 309 Knuth, B.A. 313 Knutson, R.D. 54 Kobylyanskii, G.V. 181 Kohl, K.D. 337 Kondrat'ev, S.A. 72 Kookana, R.S. 152 Kotovich, I.N. 181 Kozloff, K. 154 Kramer, L.A. 287, 322 Kramer, R.A. 116 Kreutzberger, W.A. 330 Kristiansen, H. 193 Kroes, J.G. 195 Kuchment, L.S. 53 Kuhn, Gerhard 21 Kunishi, H.M. 259 Kuo, C.H. 44 la Cour, Niels 129 Lacewell, R.D. 114 Laenen, Antonius 227 Laflen, J.M. 336, 337 Lafolie, F. 204, 205 Lam, D.C.L. 119 Landers, J.C. 313 Lane, L.J. 118, 336 Larsen, F. 193 Larsen, H.D. 228 Larson, R.S. 115 Lawrence, J.R. 43 Leatham, D.J. 114

Lee, D.J. 97 Lee, D.Y. 74 Lee, J. 295 Lee, J.G. 87 Leij, F.J. 7, 58, 136, 140, 172, 182, 267 Leonard, R.A. 61, 213, 327 Lerner, D.N. 253 Letson, D. 257 Leu, J.M. 303 Lin, J.C. 25 Lindau, C.W. 306 Linden, A.M.A. van der 171 Line, D.E. 196 Littlewood, I.G. 18 Liu, C.C.K. 96, 283 Liu, C.L. 303 Loague, K. 76, 96, 265, 274, 319 Loehr, R.C. 66 Lotse, E.G. 258 Loureiro, C.O. 291 Lovell, A.C. 114 Lowery, B. 153 Lucey, K.J. 60 Lundin, L.C. 279 Ma, L. 173 Macur, R.E. 41 Maddock, T. III 185 Madramootoo, C.A. 320 Magette, W.L. 159, 334 Makuch, J. 256 Malchow, H. 271 Mansell, R.S. 85 Mapp, H.P. 68 Marbun, O. 46 Mariam, D.W. 65 Martin, M.A. 87 Martinko, E.A. 24 Massachusetts Agricultural Experiment Station 129 Massachusetts, Division of Water Pollution Control, Geological Survey (U.S.) 308 Matthew, R. G. S. 109 Matthies, M. 214 Matthiessen, P. 47, 146 May, L. 147 McCarthy, J.F. 26 McCoy, B.J. 35, 39 McDonnell, J.J. 160 McDowell, T.C. 143 McIntosh, C.S. 189 McIsaac, G.F. 82 McKenzie, D.B. 323 McMahon, T.A. 70 McNamara, J.P. 111 Meadows, J. Kevin 75 Melone, F. 162 Messing, I. 177 Meyer, C.R. 12

Michael, J.L. 89 Michel, A.N. 44 Miller, C.T. 163 Miller, D.A. 272 Milligan, J.H. 242 Mills, M.J. 146 Mills, W.C. 32 Ming, L.S. 108 Miranda, M.J. 112 Mitchell, J.K. 82, 211 Mohamoud, Y.M. 73 Moldrup, P. 1, 254 Monke, E.J. 321 Montas, H.J. 320 Moore, I.D. 287 Moore, J.A. 282 Mostaghimi, S. 156 Mueller, T.C. 27 Murphree, C.E. 226 Mutchler, C.K. 226 Myhre, B.E.• 317 Napoleon, E.J. 314 Nash, T. 285 Nathan, R.J. 70 National Council of the Paper Industry for Air and Stream Improvement (U.S.) 278 Nearing, M.A. 304 Neary, D.G. 89, 175 Newman, J.B. •34 Nguyen, M.L. 200, 201 Nielsen, D.R. 168 Nkedi-Kizza, P. 85 Noegrohati, S. 229 Nofziger, D.L. 14 Nordstedt, R.A. 99 Norris, P.E. 68 Nutter, W.L. 309 Okwach, G.E. 17 Olimpio, Julio C. 308 Olson, R.L. 290 Opaluch, J.J. 3 Osmond, D.L. 196 Ottichilo, W.K. 103 Ouyang, Y. 325 Overton, Donald E., 264 Ozaki, Y. 49 Panday, S. 188 Pandey, S. 55 Paniconi, C. 198 Panuska, J.C. 287 Papatolios, K.T. 253 Parker, J.C. 84 Parlange, J.Y. 84, 141 Parlange, M.B. 141 Parrish, R.S. 289 Parsons, J.E. 334 Patrick, W.H. Jr 306

Penson, J.B. Jr 54 Peralta, R.C. 20 Perry, G.M. 206 Peterson, G.W. 272 Phillips, I.R. 222, 255 Pignatello, J.J. 67, 270 Pikes Peak Area Council of Governments, Geological Survey (U.S.) 21 Pinder, G. 207 Pinder, G.F. 88 Pinol, J. 246 Piper, S. 105 Piper, S.L. 69 Plate, E.J. 234 Porro, I. 297 Porter, P.S. 57 Posch, M. 79 Postma, D. 193 Potter, K.N. 194 Powers, S.E. 291 Prasher, S.O. 78 Price, Richard E. 144 Priesack, E. 6 Prinz, D. 218 Punthakey, J.F. 93 Putti, M. 198 Quintana, J.O. ‹81 Rachhpal-Singh 169 Ranjha, A.Y. 20 Rao, K.V.G.K. 250, 251 Rao, P.S.C. 170, 202 Rashmawi, E.A. 52 Ravina, I. 56 Refsgaard, J.C. 157 Reichard, Eric George 75 Rekolainen, S. 79 Requena, A.M. 20 Rhoades, J.D. 98 Ribaudo, M.O. 69 Rijtema, P.E. 195 Ritzi, R.W. Jr 45 Robarts, R.D. 43 Robson, A.J. 11 Roda, F. 246 Rodriguez, B. 236 Rogowski, A.S. 33 Rojas, K.W. 22 Rolston, D.E. 1, 35, 254 Rose, C.W. 141 Rosenthal, W.D. 92 Ross, D. 285 Roth, K. 132 Roy, W.R. 2 Rudra, R.P. 77, 117 Russell, Clifford S. 292 Russo, D. 273, 275 Russo, J. 272

Sabatini, D.A. 90 Sabbagh, G.J. 68, 179, 180 Sadeghi, A.M. 259, 298 Salvich, P.G. 123 Samsel, Theodore B. 50 Sanchez, C.A. 57 Sanders, P. 295 Sardin, M. 172 Sariev, A.L. 181 Sarin, S.C. 186 Sbaa, M. 242 Schalk, C.W. 80 Schenck, C. 192 Schmucker, J.F. 114 Schnitkey, G.D. 112 Schwart, R.B. 114 Schweich, D. 172, 301 Scott, J. C. 31 Scotter, D.R. 184, 302 Scow, K.M. 39 Segerson, K. 3 Selassie, T.G. 243 Selim, H.M. 26, 173, 174, 221 Sequeira, R.A. 290 Setia, P. 105 Seyfried, M.S. 202, 238 Shabtai, R. 176, 280, 281 Shafike, N.G. 185 Shanholtz, V.O. 284 Shani, U. 158 Sharpley, A.N. 248 Shaviv, A. 56 Shaw, R.R. 138 Sheridan, J.M. 327 Shih, S.F. 101, 317, 318 Shimojima, E. 335 Shiono, K. 109 Shirley, E.D. 118 Shirmohammadi, A. 159, 334 Shirmohammadi, Adel,1952- 9 Shnek, M. 56 Shoemaker, L.L.• 159 Shogren, Jason F. 292 Shouse, P.J. 294 Shukurov, M.S. 181 Sichani, S.A. 321 Siegel, D.I. 111 Silva, F.F. da 305 Simanton, J.R. 228, 337 Simmons, D.E. 33 Simmons, K.E. 258 Simunek, J. 164, 165 Sinange, R.K. 103 Singh, S.R. 250, 251 Singh, U. 316 Skaggs, R.W. 163 Skaggs, T.H. 7

Smith, A.E. 217 Smith, C.M. 223 Smith, C.N. 277, 289 Smith, E.G. 54 Smith, M.C. 95 Smith, R.E. 162, 208, 210 Smith, R.T. 45 Smith, S.J. 248 Smith, W.N. 78 Smolen, M.D. 197 Snyder, W.M. 32 Soderstrom, M. 102 Soerens, T.S. 90 Soileau, J.M. 240, 260 Somlyody, L. 137 Sparks, D.L. 127, 295 Spooner, J. 196, 197 Squillace, P.J. 107 Stagnitti, F. 141 Starr, J.L. 84, 298 Steenhuis, T.S. O141 Stein, A. 148 Stewart, D.J. 86 Stewart, M.K. 160 Still, D.A. 318 Stone, J.F. 68 Stone, J.J. 118 Storm, Daniel E. 161 Suarez, D.L. 164, 165 Taff, S.J. 154 Tan, Y.R. 101 Tauer, W. 218 Taylor, C.R. 54 Taylor, D.B. 116, 135, 186 Taylor, J.W. 175, 309 Tedaldi, D.J. 66 Thomas, A.W. 32 Thomas, D.L. 95 Thomas, Daniel L. 9 Thomas, M.V. 99 Thomson, N.R. 203 Thornton, P.K. 316 Thurman, E.M. 107 Tillman, Dottie 144 Tillotson, P.M. 237 Tillotson, W.R. 217 Tilman, R.W. 184 Touchton, J.T. 260 Tracy, J.C. 183 Troch, F.P. de 36 Troch, P.A. 36 Truman, C.C. 61, 213 Tucciarelli, T. 207 Turnbull, A. 146 Uchrin, C.G. 299 United States, Army, Corps of Engineers, Chicago District, U.S. Army Engineer Waterways Experiment Station 144

United States, Bureau of Land Management, Geological Survey (U.S.) 227, 286 Van Genuchten, M.T. 7, 51, 136, 140, 172, 250, 251 Van Genuchten, M.Th 84 Van Mullem, J.A. 220 Vinther, F.P. 145 Vogtle, T. 218 Wagenet, R.J. 261, 262 Waggoner, B.L. 98 Wakild, C.R. 330 Walker, W.R. 20 Wallace, R. 305 Wallach, R. 15, 131, 176, 239, 280, 281 Wallis, J.R. 121 Wambua, J. 17 Wang, Y. 154 Ward, A.D. 80 Weaver, R.D. 4 Weber, W.J. Jr 291 Weinberg, M. 328 Wells, W.G. II 314 Weltz, M.A. 228 Wetzstein, M.E. 230 Whistler, J.L. 24 White, R.E. 302 Whitehead, P.G. 11, 18 Whitmore, A.P. 151, 216 Wierenga, P.J. 130, 247, 297 Wight, J.R. 312 Wilcox, B.P. 238, 242 Wilen, J.E. 328 Williams, A.A. 189 Williams, J. 17 Williams, J.R. 180, 194, 248 Williams, R.J. 146 Willis, D. 147 Wohlgemuth, P.M. 314 Wolf, J.K. 33 Wolfaardt, G.M. 43 Wolfe, M.L. 16, 104 Wood, J.C. 34 Woolhiser, D.A. 126 Wright, J.A. 334 Wrobel, L. C. 329 Yamaguchi, T. 1, 254 Yan, J. 187 Yates, M.V. 325 Yates, S.R. 5 Yomota, A. 124 Yoneyama, T. 49 Yoo, K.H. 240, 260 Yoon, K.S. 240, 260 Zanyk, B.N. 43 Zee, S.E.A.T.M. van der 63, 134, 244 Zhang, H. 14 Zhang, W. 62 Zhu, M. 186

Zilliox, L. 192 Subject Index 2,4,5-t 214 2,4-d 92, 217 Absorption 211 Accuracy 1 Acid soils 85 Acidity 224 Activity 197 Adsorption 2, 6, 26, 132, 168, 221, 243, 249, 268, 288, 295 Afforestation 18 Aggregate data 3 Aggregates 6, 82, 155, 172, 204, 205, 323 Agricultural byproducts 108 Agricultural chemicals 15, 19, 25, 43, 54, 131, 167, 176, 196, 215, 230, 232, 256, 277, 280, 281, 283, 296, 311 Agricultural development 192 Agricultural economics 105 Agricultural land 79, 112, 154, 156, 197, 307 Agricultural policy 3, 54, 116, 231 Agricultural pollution 292 Agricultural production 72, 189, 196, 215 Agricultural regions 55 Agricultural sector 3 Agricultural soils 8, 40, 47, 49, 57, 73, 94, 133 Agricultural wastes 99, 117 Air flow 335 Air quality 89 Air temperature 312 Alabama 240, 260 Alachlor 27, 95, 211, 321 Aldicarb 171, 289 Algae 137, 271 Algorithms 44, 100, 163, 231 Alkaline soils 249 Alluvial soils 108, 249 Alternative farming 87 Aluminum oxide 85 Ammonia 306 Ammonium nitrogen 306 Anaerobic digestion 99 Analytical methods 296 Andosols 269 Angling 69 Animal wastes 99, 284 Anion exchange 255 Application date 46, 171 Application methods 112, 159 Application rates 97 Application to land 46, 156 Aquatic communities 271 Aquatic environment 25 Aquifers 26, 45, 66, 96, 193, 235, 250, 251, 253, 291, 299 Arable land 193, 326 Arable soils 244, 258, 279

Arkansas 46, 219, 324 Artemisia tridentata 242 Artificial precipitation 13 Assessment 76, 151, 318 Atrazine 67, 78, 92, 95, 180, 270, 321 Attenuation 76 Autocorrelation 273 Automation 104 Autumn 171 Availability 211 Azinphos-methyl 309 B horizons 85 Bayesian theory 232 Behavior 134 Belgium 36 Beliefs 232 Bentazone 10 Benzene 299 Bibliographies 256 Biochemical oxygen demand 330 Biodegradation 155 Biomass 6 Biomass production 137 Bioremediation 39 Bogs 111 Boron 158 Boundaries 15 Brazil 137 Broadleaved evergreen forests 246 Bromacil 94 Bromide 151, 247, 255, 268, 289, 296 Bromides 95 Bromine 269, 288 Brown earths 149, 150 Buchloe dactyloides 92 Buffering capacity 56 Cabt 87 Cadmium 134, 173, 244 Calcareous soils 56, 158 Calcium 221, 255 Calcium ions 224, 268 Calculation 269 Calibration 25 California 52, 120, 165, 249, 294, 314 Canopy 42, 228 Capacity 218, 296 Capillary fringe 199 Capillary rise 73 Carbaryl 92 Carbofuran 309, 321 Carbon 26, 259 Carbon dioxide 164, 165 Carbonates 45 Carcinoma 142 Case studies 36, 115, 283 Cash flow 114 Catchment hydrology 11, 18, 19, 28, 141, 209, 246, 260

Cation exchange 182, 221, 224, 255, 268 Cation exchange capacity 221, 268 Characteristics 70 Chemical degradation 43 Chemical properties 246 Chemicals 14, 239, 255 China 108 Chloride 255, 302 Chlorides 178 Chlorine 136 Chlorpyrifos 92, 321 Citrus reticulata 108 Clay 33, 140 Clay loam soils 259 Clay soils 41, 178, 280 Clearcutting 18 Climate 28 Climatic factors 10, 19, 42, 70, 97, 175 Climatic zones 194 Cloethocarb 10 Coarse textured soils 136 Coastal plains 159 Coasts 227 Colorado 190 Commercial soil additives 112 Compact soils 268 Comparisons 1, 15, 26, 79, 85, 183, 194, 266 Composts 305 Computer assisted instruction 285 Computer graphics 119, 121 Computer hardware 121 Computer simulation 2, 27, 29, 61, 78, 87, 119, 121, 151, 169, 195, 208, 236, 238, 285, 287, 315, 320 Computer software 40, 48, 118, 119, 121, 138, 211, 236, 310 Computer techniques 12, 29, 68, 104, 272, 307 Computers 223 Concentration 47, 65, 107, 253 Condensation 181 Coniferous forests 37, 193 Connecticut 67, 141 Conservation tillage 240, 260 Constraints 44 Contaminants 26, 43, 88, 140, 170, 282, 323 Contamination 3, 54, 142, 176, 239, 280, 281 Continuous cropping 87, 171 Control methods 232 Convection 1, 84, 269 Cooperative extension service 263 Corn belt of U.S.A. 105 Corn belt states of U.S.A. 87 Cost benefit analysis 215 Cost effectiveness analysis 154 Costa Rica 202 Costs 38, 116, 185, 206, 207, 231, 232 Cotton 290 Crop growth stage 194 Crop management 68, 194, 305

Crop production 46, 91, 108, 112, 179, 316 Crop residues 73, 108 Crop yield 38, 46, 97, 102, 206, 312 Cropping systems 55, 159, 202 Crops 102, 218, 337 Crumbs 157 Crusts 73 Cultivation 159 Culture media 305 Cyanazine 167, 321 Cycling 108, 200, 201 Cynodon dactylon 92, 217 Dairy farms 114 Dairy wastes 114 Data analysis 190 Data banks 12 Data collection 24 Databases 40, 48, 119, 190, 272 Decision making 55, 185, 263, 328 Decomposition 108 Degradation 41, 170, 225 Delta soils 108 Deltas 108, 120 Denitrification 49, 100, 145, 157, 254, 259 Denmark 100, 145 Depth 251, 306 Desertification 103 Design 20 Desorption 2, 39, 56, 249, 281 Deterioration 331 Determination 84, 85, 148, 305 Deterministic models 51, 130, 134, 183, 247 Deuterium 160 Diazinon 92 Dicamba 41, 92 Diffusion 6, 39, 151, 157, 184, 205, 243, 269, 306, 335 Diffusion models 56, 177, 178, 184 Diffusivity 6, 149, 150, 157, 268, 306, 335 Discharge 111, 199, 246 Dispersion 1, 49, 84, 249, 259, 289, 293 Dissolving 249 Distribution 222 Disturbed soils 148, 268 Ditches 108, 296 Diuron 171 Drainage 42, 64, 79, 161, 179, 195, 220, 234, 249, 279, 296, 326, 328, 334 Drainage water 108, 249, 250, 251 Drained conditions 163, 243 Drinking water 60, 142, 216, 311, 331 Dry matter accumulation 108 Dry season 108 Dynamic models 53, 120, 206, 230, 231 Dynamic programming 186 Dynamics 172 Eastern scotland 224 Ecology 111

Econometric models 189 Economic analysis 135 Economic evaluation 55 Economic impact 38, 54, 68, 87, 147, 186, 189, 206 Economics 197 Ecosystems 89 Edaphic factors 228 Effects 72 Effluents 251 Electrical conductivity 243 England 47, 146, 216, 253 Environment 143 Environmental factors 4, 10, 165 Environmental impact 38, 68, 87, 89, 143, 147, 186, 215, 257, 263, 284, 315, 316 Environmental legislation 230, 307 Environmental policy 112, 115 Environmental protection 143, 313, 331 Epidemiology 142 Equations 5, 15, 51, 56, 65, 70, 74, 88, 90, 127, 134, 177, 181, 184, 188, 198, 301, 337 Equilibrium 56, 66, 222, 268, 288 Erodibility 337 Erosion 17, 23, 87, 108, 118, 154, 179, 190, 226, 260, 287, 310, 314, 320, 336 Erosion control 34, 159, 242, 285 Errors 52, 76, 140, 151 Estimated costs 114 Estimatesª 79 Estimation 52, 69, 71, 194, 265 Eutrophication 137 Evaluation 151 Evaporation 42, 141, 326, 335 Evapotranspiration 34, 80, 171, 179, 194, 326 Exchangeable cations 221, 222, 268 Exchangeable sodium 221, 243, 255 Experimental design 151 Experimental plots 322 Expert systems 16, 119 Extraction 323 Farm income 206 Farm indebtedness 114 Farm inputs 135, 206, 231 Farm management 186, 206, 328 Farmers' attitudes 232 Farming systems 135, 186 Farmland 23, 191, 195, 234 Farmyard manure 112 Feasibility 55 Federal programs 34, 105, 313 Fenamiphos 283 Fens 111 Fenvalerate 309 Fertigation 91 Fertilizer requirement determination 91, 201, 233 Fertilizer technology 91 Fertilizers 22, 92, 106, 108, 159, 202, 305

Festuca pratensis 326 Field experimentation 210 Field tests 25, 95 Finite element analysis 45, 96 Finland 79 Fish 115 Fishery management 86, 120, 139 Fishing 147 Fixation 85 Flood dams and reservoirs 144 Flood irrigation 94 Flooded rice 306 Flooding 124 Floods 36, 53 Florida 57, 85, 99, 101, 143, 263, 317, 318 Flow 7, 11, 28, 59, 70, 71, 79, 108, 128, 131, 220, 299 Fluids 91 Food chains 86 Food safety 54 Forecasting 36 Forest management 175 Forest soils 37, 197 Forest steppe 53 Forestry 89 Forests 72, 175, 307 Formation 72 France 192 Frequency 79 Fresh water 120 Frost 279 Frozen conditions 279 Fuel tanks 74 Fungicides 106 Furrow irrigation 20 Game theory 230 Geochemistry 66, 100, 193 Geographic information systems 31, 50, 129, 139, 308 Geographical distribution 101, 194, 317 Geographical information systems 263 Geography 103, 272, 284, 307 Geological sedimentation 19, 77, 248, 285 Geology 111 Geomorphology 192 Georgia 61, 95, 175, 180, 189, 230, 277, 327 German federal republic 10, 234 Glacial till soils 37 Gley soils 269 Glycine max 38, 45, 87, 165 Golf courses 106, 217, 315 Golf green soils 106, 217 Gossypium 240 Gossypium hirsutum 260 Grain crops 192 Grape marc 305 Graphic arts 310 Grasses 46 Grassland management 223, 242

Grassland soils 216 Grasslands 192 Grazing effects 200, 201, 223 Green and ampt equation 73, 220 Green manures 81 Greenhouses 181 Ground vegetation 42, 228 Groundwater 3, 28, 30, 54, 61, 63, 66, 95, 98, 101, 102, 105, 111, 123, 143, 180, 183, 185, 197, 199, 207, 215, 231, 237, 246, 249, 252, 277, 299, 309, 311, 317, 321, 325 Groundwater flow 28, 52, 75, 88, 90, 100, 111, 188, 198, 235, 298, 301 Groundwater level 28 Groundwater pollution 2, 14, 16, 20, 29, 33, 35, 38, 43, 44, 45, 49, 68, 74, 88, 89, 90, 106, 107, 116, 128, 135, 142, 143, 155, 159, 183, 185, 188, 189, 191, 192, 193, 195, 198, 203, 206, 212, 214, 230, 231, 235, 245, 253, 256, 274, 283, 291, 295, 296, 297 Groundwater recharge 33, 191, 195, 253 Growth 108 Growth models 208 Growth rate 6 Gully erosion 285 Gypsum 249 Habitats 23, 115 Half life 41 Hapludults 13, 221 Hatcheries 120 Hawaii 76, 106, 283 Health hazards 331 Heat flow 164, 165, 266 Heathland 193 Heavy metals 133, 173 Height 13 Herbage 312 Herbicide residues 27, 67, 92, 94, 106, 107, 217, 270 Heterogeneity 134 High water tables 108 Hill grasslands 62 Histosols 57 Hordeum vulgare 134, 145, 326 Horizons 224 Horizontal flow 58, 259, 275, 298 Humid tropics 202 Hyacinths 99 Hydraulic conductivity 45, 62, 66, 73, 88, 148, 178, 223, 225, 261, 262, 273, 275 Hydraulic resistance 110 Hydraulics 44, 109, 128 Hydrodynamic dispersion 5, 63, 71, 182, 184, 298 Hydrodynamics 235 Hydrogen ions 224 Hydrogeology 50 Hydrologic cycle 286 Hydrologic models 227 Hydrological data 70, 190, 312 Hydrology 9, 64, 72, 80, 104, 111, 113, 121, 187, 208, 259,

324, 334 Hydrolysis 306 Hydromorphic soils 192 Hysteresis 249, 305 Idaho 23, 230 Identification 36 Illinois 73, 82 Immiscible displacement 203 Improvement 12 Inactivation 325 Inceptisols 13 Income 54 Incorporation 280, 306 Indexes 57, 143, 284 India 251 Indiana 313, 321 Indicator plants 271 Indicator species 111, 271 Infiltration 33, 62, 66, 73, 118, 125, 130, 162, 176, 210, 220, 228, 247, 279, 281, 319 Information 232 Information retrieval 12 Information storage 12 Information storage and retrieval systems 139, 278 Information systems 3, 23, 138, 256, 307 Insecticide residues 92, 106 Integrated pest management 315 Intensive cropping 192 Interactions 210 Interception 42, 228 Interface 140, 267 Interrill erosion 13 Iodide 296 Ion exchange 173, 243 Ion transport 259 Ions 246 Iowa 60, 107, 230 Iron oxides 85 Irrigated conditions 201 Irrigated soils 102, 249 Irrigation 55, 66, 68, 97, 123, 147, 249, 305 Irrigation scheduling 41, 102 Irrigation water 91, 102, 108, 235, 249, 328 Japan 124 Kansas 24, 190 Kaolinite 221 Kenya 17, 103 Kinematics 124, 126 Kinetics 26, 56, 84, 85, 118, 125, 127, 152, 172, 173, 243, 281, 288 Labeling 311 Laboratory methods 85, 259, 266, 268, 298, 306 Laboratory tests 128 Lakes 86, 115, 313 Land diversion 313 Land management 28, 138, 154, 285, 313 Land types 285, 307

Land use 154, 192, 193, 197, 285, 307 Landsat 24, 318 Lasers 13 Law 114 Law enforcement 331 Lawns and turf 315 Layered soils 125, 136, 140, 267 Leachates 33, 106, 231 Leaching 10, 20, 27, 29, 38, 41, 47, 51, 57, 61, 63, 67, 76, 78, 81, 94, 95, 102, 105, 106, 123, 133, 134, 140, 143, 145, 148, 151, 153, 168, 171, 174, 175, 178, 180, 184, 194, 200, 201, 202, 216, 217, 222, 229, 233, 237, 243, 245, 249, 252, 254, 255, 258, 259, 263, 270, 273, 274, 289, 299, 302, 309, 316, 321 Leakage 74 Legal liability 230 Legumes 186 Length 84 Leys 326 Linear models 132, 261, 262 Linuron 152 Liquid fertilizers 91 Literature reviews 89, 99, 174, 200, 201, 300 Livestock enterprises 112 Livestock numbers 112 Loam soils 1, 145 Lolium multiflorum 145 Long term experiments 66, 145 Losses 115, 156, 159 Losses from soil 81, 117, 213, 245, 260, 302 Losses from soil systems 20, 46, 57, 61, 108, 145, 169, 202, 211, 216, 223, 228, 259, 304, 306, 320, 322 Louisiana 179, 180, 221 Lowland areas 269 Lysimeters 10 Lysimetry 153 Macropore flow 37, 80, 177, 178, 261, 262 Macropores 22, 37, 177, 204, 261, 262, 269 Madhya pradesh 55 Magnesium 221, 222, 255 Maize 112, 192 Mali 209 Management 12, 40, 91, 137 Manures 99 Mapping 23 Maps 102 Marine resources 139 Markets 328 Maryland 159, 259 Mass transfer 291 Massachusetts 106 Mathematical models 1, 3, 4, 5, 6, 7, 13, 15, 26, 32, 35, 39, 49, 51, 52, 53, 56, 58, 60, 62, 72, 73, 79, 84, 85, 91, 92, 94, 96, 97, 98, 99, 100, 106, 112, 114, 115, 124, 126, 128, 131, 135, 136, 140, 141, 142, 147, 149, 150, 157, 158, 160, 162, 163, 164, 165, 170, 171, 172, 173, 174, 176, 177, 178, 180, 181, 182, 185, 188, 198, 199, 205, 210, 216, 217, 221,

225, 232, 235, 239, 240, 241, 242, 244, 246, 248, 249, 250, 251, 252, 254, 255, 257, 259, 266, 267, 268, 269, 270, 271, 274, 276, 277, 280, 281, 288, 289, 291, 293, 294, 295, 299, 300, 301, 302, 305, 306, 319, 323, 324, 335 Mathematics 13, 74, 90, 151 Matric potential 266 McCook Reservoir (Ill.) 144 Measurement 13, 47, 145, 149, 150, 151, 153, 160, 207, 209, 215, 247, 266, 269, 270, 285 Mecoprop 47 Medicago sativa 87 Mediterranean climate 246 Meltwater 37, 53 Metals 295 Meteorological factors 194, 208, 252, 326 Methane 323 Methane production 99 Methodology 38, 168, 194, 237, 263 Metolachlor 67, 180, 270, 289 Metribuzin 27 Michigan 29, 115 Microbial activities 168 Microbial contamination 282 Microbial degradation 2, 6, 39, 43 Microcomputers 119, 285 Microeconomic analysis 3, 87 Microeconomics 4 Mineralization 81, 233, 258 Minnesota 107, 154, 230, 313 Mississippi 226 Missouri 165 Mixtures 305 Models 36, 40, 42, 43, 47, 54, 57, 65, 66, 67, 69, 70, 102, 103, 107, 108, 117, 125, 137, 143, 146, 190, 192, 193, 196, 197, 203, 212, 215, 218, 220, 222, 253, 267, 272, 282, 284, 296, 297, 303, 307, 310, 313, 325, 330 Mole drainage 302 Monitoring 47, 79, 91 Montana 220 Monte carlo method 63 Mounds 111 Mountain areas 159 Movement 282 Movement in soil 6, 14, 22, 26, 33, 43, 45, 57, 68, 74, 76, 84, 85, 91, 94, 96, 125, 132, 140, 151, 152, 153, 158, 174, 182, 183, 184, 194, 208, 214, 221, 222, 243, 249, 250, 251, 254, 255, 259, 267, 268, 269, 283, 288, 291, 296, 297, 300, 325 Movement to roots 76 Mulches 17 Multivariate analysis 70 Musa paradisiaca 108 Nebraska 110, 190, 191 Netherlands 148, 195, 244, 252 New Jersey 295, 299 New Mexico 130, 247 New South Wales 70, 123

New York 111 New Zealand 160, 200, 201, 223 Nitrate 49, 81, 100, 136, 142, 148, 191, 195, 234, 259 Nitrate fertilizers 142, 191, 195, 234 Nitrate nitrogen 60, 151, 216, 258, 259 Nitrates 29, 45, 116, 167, 192, 193, 206, 231, 233, 253 Nitrification 254, 258 Nitrogen 46, 72, 81, 91, 106, 108, 145, 156, 159, 169, 194, 216, 254, 258, 260 Nitrogen balance 81, 258 Nitrogen fertilizers 16, 60, 186, 231, 233, 316, 326 Nontarget effects 89 Norflurazon 27 North Carolina 13, 38, 330 Northern scotland 224 Nutrient availability 56, 81 Nutrient content 108 Nutrient intake 200, 201 Nutrient requirements 91 Nutrient sources 259 Nutrient uptake 56, 81, 91 Nutrients 72, 108, 202, 212 Objectives 86 Ohio 45 Oklahoma 68, 113, 187, 248, 324 On line 36 Ontario 117 Optimization 115 Optimization methods 44 Oregon 206 Organic compounds 2, 6, 74, 90, 155, 188 Organic fertilizers 156 Organic matter 26, 108 Organic wastes 156 Organochlorine insecticides 229 Oryza sativa 108, 269, 306 Overland flow 15, 77, 107, 124, 126, 176, 199, 210, 239, 280, 281 Oxidation 100, 249 Oxygen consumption 157 Oxygen transport 157 Paddy soils 268, 269, 306 Pans 268 Participation 69 Particle size 65, 335 Particle size distribution 204, 205 Particle velocity 205 Pastures 200, 201 Peatlands 111 Pennsylvania 258 Percolation 34, 61, 194 Permeability 58, 73 Permethrin 309 Persistence 41, 171, 274 Pest control 68 Pesticide residues 10, 54, 106, 146, 214, 289 Pesticides 20, 22, 25, 30, 38, 61, 63, 68, 76, 87, 89, 95,

105, 115, 143, 153, 175, 189, 211, 212, 213, 237, 245, 252, 263, 274, 311, 315 Petroleum 74, 128, 299 Petroleum hydrocarbons 74 Ph 91, 306 Phosphates 167 Phosphorus 46, 56, 57, 72, 79, 85, 112, 200, 260 Phosphorus pentoxide 108 Phthalates 259 Physical models 37, 53, 283, 326 Physicochemical properties 51, 63, 134, 221, 249, 294 Phytoplankton 271 Picea abies 37 Picloram 288 Pig farming 112 Pinus sylvestris 37 Pinus taeda 175 Placement 44 Plains 159 Planning 197 Plant communities 111, 190 Plant density 62 Plant development 326 Plant nutrition 91 Plant water relations 8 Plants 252 Plastic cladding 181 Plowing 216 Podzolic soils 255 Pollutants 2, 14, 16, 39, 90, 96, 117, 147, 167, 183, 188, 198, 208, 210, 235, 253, 257, 274, 291, 295, 297, 301, 325 Polluted soils 39, 74, 244 Pollution 23, 79, 115, 208, 232, 272, 287, 316 Pollution control 112, 231 Populations 120 Pore size distribution 276 Pore volume 268, 269 Pores 6, 221, 268 Porosity 148, 172, 178, 204, 205 Porous media 51 Pot culture 305 Potassium 108, 221, 222, 255 Potassium bromide 184 Potassium chloride 302 Potassium nitrate 259 Poultry manure 46, 219 Practice 12, 159 Prairies 228 Precipitation 37, 41, 60, 95, 171, 187, 220, 238, 312, 326 Precipitation (Meteorology) 286 Prediction 7, 12, 14, 25, 56, 65, 66, 71, 81, 96, 130, 141, 163, 164, 165, 169, 170, 175, 176, 178, 203, 209, 220, 221, 222, 223, 224, 228, 238, 242, 247, 248, 250, 251, 253, 260, 273, 274, 280, 281, 289, 293, 294, 296, 297, 304, 309, 312, 322, 336, 337 Prevention 29, 296 Probabilistic models 53, 71, 183

Probabilities 161 Probability 32 Problem solving 44, 187, 192 Production 164, 165 Profiles 67, 76, 134, 140, 148, 175, 239, 258, 289 Profit functions 189 Profitability 38, 114, 135 Program development 12 Program evaluation 313 Programming 187 Public agencies 331 Public health 143 Pulp and paper industry 330 Pulp mill effluent 330 Pumps 44 Pyrites 100 Qualitative techniques 140 Quality standards 331 Quantitative analysis 49, 120, 128 Quantitative techniques 13 Quebec 320 Rain 11, 14, 18, 32, 36, 42, 53, 55, 62, 64, 70, 73, 76, 77, 108, 113, 117, 125, 126, 160, 162, 167, 176, 199, 209, 210, 213, 226, 228, 241, 265, 281, 303, 319, 324, 327 Rainy season 108 Random sampling 88 Rangeland soils 319 Rangelands 190, 228, 238, 242, 312, 319, 337 Ranking 143, 272, 284 Ratios 243 Recharge 66, 123 Reclamation 124, 243 Redistribution 162, 247 Redox reactions 100 Reduction 100, 193 Reflectance 65 Regional planning 129 Registration 30, 143 Regression analysis 229, 322 Regulations 120, 189, 230, 231, 232, 311 Relationships 176 Reliability 232 Remote sensing 24, 65, 103, 138, 209 Removal 72 Replication 151 Reserved areas 34 Reservoirs ý137, 144 Respiration 164 Responses 65 Retention 173 Returns 38, 112 Reviews 197 Rhizosphere 149, 150, 169 Rill erosion 337 Riparian vegetation 23 Risk 25, 55, 106, 114, 142, 234, 235, 263 River water 52, 107, 257

Rivers 147, 234, 236, 330 Root exudates 149, 150 Root systems 91 Root zone flux 22, 212 Roots 108, 268, 269 Rotations 45, 87 Rsfsr 72 Runoff 11, 17, 18, 19, 25, 28, 32, 34, 36, 37, 62, 64, 68, 70, 73, 77, 79, 80, 82, 87, 95, 105, 106, 110, 112, 113, 118, 124, 126, 141, 162, 167, 176, 179, 180, 181, 187, 190, 195, 199, 211, 213, 219, 220, 223, 226, 227, 228, 234, 238, 239, 240, 241, 242, 248, 260, 263, 264, 265, 280, 281, 285, 303, 309, 310, 312, 319, 320, 322, 324, 326, 327 Runoff farming 218 Runoff irrigation 218 Runoff water 15, 42, 46, 53, 55, 72, 92, 108, 125, 131, 156, 209, 216, 239, 282, 313 Rural areas 70 Saccharum officinarum 108 Saline sodic soils 243 Saline soils 243 Saline water 66, 97, 102, 235 Salinity 52, 91, 123 Salmon 120 Salts in soil 243, 249 Salvage felling and logging 314 Samples 270 Sampling 79, 102, 277 Sand 140, 221, 323 Sandy loam soils 27, 259, 266, 273 Sandy soils 85, 134, 145, 171, 252 Satellite imagery 103, 209 Saturated conditions 152, 243, 249 Saturated flow 51 Saturated hydraulic conductivity 37, 59, 130, 141, 276, 305, 319 Scotland 11, 18 Screening 284 Seasonal variation 60, 246, 257 Sediment 26, 65, 72, 108, 167, 285, 314, 320 Sediment transport 109, 264 Sediment yield 82, 154, 226 Seed orchards 309 Seepage 80, 141, 183 Selection 102 Selection methods 307 Selenium 168, 249 Semiarid soils 130, 247 Semiarid zones 17, 55, 209 Sewage 137, 329 Sewage effluent 307 Sewage effluent disposal 307 Sheep 200, 201 Silt loam soils 184, 280, 288, 302, 306 Silviculture O89 Simazine 47, 152 Simulation 58, 100, 120, 162, 163, 170, 183, 199, 209, 213,

224, 251, 259, 261, 262, 269, 275, 326 Simulation models 1, 8, 10, 11, 12, 14, 17, 18, 19, 20, 22, 24, 25, 27, 28, 30, 33, 34, 37, 38, 41, 44, 45, 55, 64, 68, 74, 76, 77, 80, 81, 82, 85, 86, 87, 89, 92, 95, 104, 106, 110, 111, 113, 118, 119, 121, 123, 127, 128, 142, 148, 150, 151, 152, 153, 154, 155, 156, 158, 159, 164, 165, 167, 168, 169, 173, 175, 179, 182, 186, 187, 191, 194, 195, 199, 200, 201, 202, 204, 206, 207, 208, 211, 213, 217, 219, 223, 224, 226, 228, 233, 236, 237, 242, 245, 256, 257, 258, 260, 263, 265, 266, 268, 279, 283, 285, 289, 290, 298, 302, 304, 309, 311, 312, 316, 319, 321, 322, 327, 328, 334 Site factors 3, 228, 284, 307 Site selection 218 Size 13, 157 Slope 62 Slopes 37, 141, 226 Sloping land 124, 125, 176, 281 Snow 279 Social values 307 Sodium 243, 255 Soil 102, 134, 155, 218, 229, 283, 295, 337 Soil air 157, 168 Soil amendments 219 Soil analysis 84, 152, 254 Soil biology 164 Soil boundaries 13, 140, 267 Soil chemistry 57, 66, 127, 164, 168, 174, 224, 258, 300 Soil compaction 269 Soil conservation 17, 34, 105, 138, 241, 285 Soil depth 8, 27, 37, 59, 108, 141, 210, 225, 249, 255, 265, 279, 280, 289 Soil erosion 161, 264 Soil fertility 17, 202, 233 Soil flora 6, 39, 168 Soil management 306 Soil morphological features 171 Soil morphology 148 Soil movement 115 Soil organic matter 85, 148, 216, 244 Soil ph 244, 295 Soil physical properties 141, 307, 326 Soil physics 56, 177, 178 Soil pollution 2, 14, 35, 39, 43, 67, 74, 76, 90, 112, 128, 134, 155, 156, 159, 188, 193, 203, 270, 291, 295, 297, 301, 323 Soil pore system 6, 172, 279, 288, 298 Soil properties 10, 40, 47, 57, 78, 82, 95, 117, 252, 263, 273 Soil salinity 97, 102, 251 Soil solution 1, 6, 15, 56, 84, 91, 221, 222, 239, 244, 255 Soil sterilization 168 Soil structure 148 Soil surveys 148 Soil temperature 37, 41, 145, 153, 171, 266, 279, 325 Soil testing 1, 151 Soil texture 8, 20, 148, 319 Soil types 65, 192, 228, 293, 294, 335 Soil types (genetic) 173

Soil variability 130, 136, 148, 194, 244, 247, 307 Soil water 22, 49, 62, 71, 95, 130, 141, 145, 153, 157, 160, 176, 194, 221, 246, 247, 266, 275, 288, 298, 326 Soil water balance 55, 141, 163, 194, 202, 326 Soil water content 1, 13, 73, 91, 148, 157, 162, 183, 222, 261, 262, 265, 266, 279, 281, 325 Soil water movement 1, 8, 41, 74, 85, 90, 136, 162, 175, 184, 188, 198, 199, 214, 243, 254, 255, 266, 267, 288, 289, 301 Soil water potential 305 Soil water regimes 325 Soil water retention 37, 136, 148, 266, 273, 305 Soil zonation 225 Solar radiation 312 Solubility 56, 133 Solutes 1, 5, 6, 7, 8, 14, 49, 51, 58, 59, 71, 84, 98, 130, 132, 140, 149, 150, 157, 163, 170, 172, 174, 176, 177, 178, 182, 184, 199, 210, 225, 243, 246, 247, 249, 250, 251, 267, 268, 275, 276, 281, 283, 293, 294, 297, 300, 302 Solvents 229 Sorghum bicolor 97 Sorption 39, 56, 57, 63, 85, 149, 150, 152, 170, 173, 229, 244, 259, 270, 281, 289, 306 Sorption isotherms 26, 85, 150, 244, 288 South Dakota 212 Southern plains states of U.S.A. 241 Southern states of U.S.A. 54, 89, 309 Soybeans 55 Spacing 251 Spain 236, 246 Spatial distribution 3, 6, 33, 91, 100, 102, 164, 165, 221, 249, 266, 271 Spatial variation 13, 33, 63, 71, 148, 194, 244, 265, 266, 273, 275, 276, 279 Species diversity 89 Splash erosion 77 Spodosols 85, 244 Spread 296 Spreading 267 Spring 171 Standards 295 Statistical analysis 151, 273 Statistical data 151 Statistical methods 267 Steady flow 165, 297 Steppes 228 Stochastic models 59, 63, 88, 116, 207, 234, 273, 275, 312 Stochastic programming 116 Storage 194, 258 Storms 162, 220, 226, 248 Straw 99 Stream flow 18, 28, 60, 113, 160, 246, 324 Streams 82, 224, 246 Strontium 268 Subsoil 33, 221, 265, 269 Substrates 6 Subsurface barriers 140 Subsurface drainage 251, 327

Subsurface irrigation 334 Subsurface layers 5, 85, 199, 291, 335 Subsurface runoff 40 Subtropics 108, 143 Sulfur 201 Superphosphates 200, 201 Supply response 189 Surface layers 13, 73, 131, 225, 283 Surface roughness 13, 110 Surface water 15, 28, 46, 106, 111, 197, 210, 215, 241, 309 Survival 114 Susceptibility 16 Suspensions 65 Sustainability 108, 316 Swamps 111 Sweden 37, 326 Systems 331 Systems approach 283 Taiwan 303 Taxes 189, 206, 232 Teaching methods 285 Technology 4 Technology transfer 138 Temperature 246, 306 Temporal variation 91, 108, 151, 271 Terbufos 211 Terrain 287 Tests 296 Texas 16, 28, 66, 114, 190, 248, 257 Thematic mapper 24 Theory 127, 270, 290 Thermal conductivity 266 Thermal diffusivity 266 Thermodynamics 66 Thickness 148 Tile drainage 80, 250, 251 Tillage 13, 17, 73, 82, 110, 159, 240, 260, 322 Time 172 Time lag 249 Timing 46 Toluene 299, 323 Topography 13, 126, 307 Topsoil 178, 265 Toxicity 143 Toxicology 263 Tracers 289, 296 Traditional farming 240 Transformation 63, 156, 170, 293 Transient flow 8, 51, 165, 297 Transpiration 326 Transport 88 Transport processes 1, 2, 5, 6, 7, 8, 13, 15, 26, 39, 49, 51, 56, 58, 59, 71, 74, 79, 84, 85, 90, 91, 94, 98, 100, 127, 130, 131, 132, 136, 149, 150, 152, 157, 158, 160, 163, 164, 165, 168, 169, 170, 172, 173, 174, 176, 177, 182, 183, 188, 193, 198, 199, 204, 205, 208, 210, 221, 225, 235, 239, 244, 247, 249, 250, 254, 261, 262, 266, 267, 268, 269, 270, 275, 276,

281, 283, 288, 293, 294, 298, 300, 301, 306, 323, 325, 335 Transverse distribution 58 Trends 120 Trichloroethylene 2 Trickle irrigation 91 Tritiated water 184 Triticum aestivum 97, 165, 233 Triticum turgidum 97 Tritium 247 Tunisia 102 Turbidity 65 Turbulent flow 335 Two dimensional flow 58 U.S.A. 4, 12, 34, 183, 194, 328, 331 U.S.S.R.in europe 53, 72 Uncertainty 14 Underground storage 74 Undisturbed sampling 259 Unfrozen water 279 Universal soil loss equation 285, 336 Unsaturated flow 96, 136, 157, 163, 199, 225, 273, 275, 276, 297 Unsaturated hydraulic conductivity 305 Upland areas 110, 124 Uptake 63, 133, 134, 252, 258 Upward movement 111 Urban areas 197 Urea 306 Urea fertilizers 169 Usage 38, 215, 231 Usda 12, 105, 138 Uses 189 Utah 20 Validity 244, 290, 327 Vapor 2, 323 Variance 267 Variation 14, 151 Vegetation 28, 111, 190 Velocity 199, 259, 269, 288, 289, 298 Vermont 230, 307 Vertical movement 275, 289, 293, 309 Victoria 70, 235 Virginia 116, 135, 186, 284 Viruses 325 Volatile compounds 35 Volatilization 2, 169, 306 Volcanic ash 305 Wales 216 Washington 147 Waste disposal 46, 99 Waste disposal sites 307 Waste treatment 137 Waste water 66 Waste water treatment 236 Wastes 185 Water 31, 83, 102, 166, 199, 292, 329, 332 Water allocation 328

Water balance 153, 327 Water conservation 32 Water content 246 Water distribution 199, 220, 331 Water erosion 12, 34, 82, 228, 241, 242, 285, 304, 322, 336, 337 Water flow 22, 37, 48, 49, 51, 110, 120, 130, 141, 160, 164, 165, 171, 208, 247, 250, 261, 262, 275, 279 Water harvesting 55, 209 Water holding capacity 141 Water management 20, 28, 48, 52, 80, 98, 101, 115, 119, 120, 121, 138, 185, 207, 236, 334 Water policy 4, 69, 328 Water pollution 3, 24, 47, 57, 60, 61, 69, 72, 78, 87, 106, 107, 146, 147, 154, 156, 180, 195, 196, 197, 234, 236, 252, 257, 258, 260, 263, 277, 284, 321 Water purification 137, 147 Water quality 4, 9, 19, 21, 24, 30, 40, 46, 48, 52, 54, 60, 65, 66, 69, 86, 89, 97, 98, 105, 108, 109, 111, 114, 120, 122, 135, 137, 144, 147, 154, 163, 190, 194, 197, 207, 215, 219, 223, 224, 231, 234, 236, 241, 245, 246, 251, 257, 260, 263, 271, 277, 278, 287, 308, 311, 313, 317, 318, 328, 329, 330, 331, 332, 333, 334 Water quality management 83, 122, 292 Water recreation 147 Water relations 55 Water requirements 218 Water resources 113, 119, 120, 121, 137, 197 Water storage 218 Water supply 185 Water table 52, 80, 111, 163, 179, 203, 251, 334 Water transport 282 Water uptake 171 Water use efficiency 328 Water vapor 266, 335 Water yield 70, 141 Water, Underground 75, 308 Watershed management 129, 139, 187, 259 Watersheds 11, 18, 23, 24, 28, 32, 53, 64, 70, 72, 89, 113, 115, 126, 141, 154, 160, 175, 179, 190, 209, 224, 226, 238, 241, 246, 265, 272, 286, 303, 310, 320, 324, 327 Weather 175 Weather data 53, 312 Weed competition 38 Weed control 38 Wells 101, 102, 253, 317 West Africa 218 Wetlands 313, 318 Wetting front 73, 130 Wheat 55 Wind 335 Wisconsin 296, 313 Wyoming 190 Xylene 299 Yield forecasting 312 Yield losses 102 Yield response functions 55

Zea mays 45, 61, 87, 97, 165, 171, 179, 252, 322 Zoning 53 Zooplankton 271 *************************************************************** SEARCH STRATEGY Set Items Description S1 40216 (MODEL?)/TI,DE,ID S2 13239 (POLLUTION(2N)AGRICULTUR? OR AGRICULTURAL()WASTE? OR WATER()QUALITY OR GROUNDWATER()POLLUTION OR TRANSPORT()PROCESSES OR LEACHING OR RUNOFF)/TI,DE,ID S3 1606 S1 AND S2 S4 1333 (ANSWERS OR CNS OR STORM OR ARM OR CREAMS)/TI,DE,ID S5 42707 (MODEL? OR SIMULATION? ?)/TI,DE,ID S6 124 S4 AND S5 S7 98 (CPM OR GLEAMS OR NTRM OR PRZM OR WEPP OR AGNPS OR HSPF OR NPS OR SWAM OR SWMM OR SWRRB)/TI S8 356 (GIS OR GEOGRAPHIC()INFORMATION()SYSTEM? ?)/TI,DE,ID S9 73680 SH=(P200 OR WOOO OR J800) S10 76 S8 AND S9 S11 1788 S3 OR S6 OR S7 OR S10 S12 394 S11 AND (PY=(1991 OR 1992 OR 1993)

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