hydrologie.orghydrologie.org/redbooks/a270/p270 description, contents, … · web viewedited by...

Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological ModelsEdited by A. J. Dolman, A. J. Hall, M. L. Kavvas, T. Oki & J. W. Pomeroy IAHS Publication no. 270 (published July 2001) in the IAHS Series of Proceedings and ReportsISBN 1-901502-61-9; 372 + x pp.; price £ 59.50

Soil–vegetation–atmosphere interactions determine, to a large extent, the global climate and the behaviour of the hydrological cycle. Model predictions thus depend critically on adequate paramet-erization of this interaction. This volume represents a “state of the art” in Soil–Vegetation–Atmosphere Transfer (SVAT) modelling in the hydrological community; it contains 48 papers presented at a symposium on SVAT schemes held during the Sixth IAHS Scientific Assembly (Maastricht, July 2001).

Several key issues in SVAT models are poorly parameterized or simply not well enough understood. Current SVAT schemes include increasingly complex descriptions of the physical mechanisms governing land surface processes requiring large numbers of soil and land surface parameters controlling the vertical fluxes. The underlying rationale is that improved process representation will result in parameters which are easier to measure or estimate, and in improved model performance and robustness. However, this is not necessarily so. Studies show that characterizing surface properties is fraught with difficulties, as determining representative parameterizations is non-trivial due to our inability to accurately measure land surface properties. Hence, data assimilation, whereby measurements are integrated with models, is increasingly used to keep hydrological models on track. Remote sensing of the state of the land surface plays is important in efforts to improve data assimilation. However, these issues are particularly difficult for snow-covered areas, where vegetation communities are strongly coupled with patterns of snow accumulation and snowmelt.

This book is organized into five sections: General SVAT Modelling SVAT and Precipitation Processes at Large ScalesParameter Estimation of Large-Scale Hydrological ModelsData Assimilation in Large-Scale Hydrological ModelsSnow–Vegetation Interactions

Contents

Preface by Han Dolman, Alan Hall, Levent Kavvas, Taikan Oki & John Pomeroy v

1 General SVAT Modelling

Relative influence of vertical and horizontal processes in large-scale water and energy balance modelling Eleanor Blyth 3

The representation of the seasonal hydrological cycle in a regional climate model in west Europe A. J. Dolman, M. Soet, B. J. J. M. Van Den Hurk, R. J. M. Ijpelaar & R. J. Ronda 11

Hydrological simulation by SiB2-Paddy in the Chao Phraya River basin, Thailand Wonsik Kim, Yasushi Agata, Shinjiro Kanae, Taikan Oki & Katumi Musiake 19

A framework for coupling atmospheric and hydrological models Alain Pietroniro, Eric D. Soulis, Ken Snelgrove & Nick Kouwen 27

Regional mechanistic estimations of sugar-cane water use Angel Utset & Gilberto Lopez 35

A bucket with a bottom hole (BBH) model of soil hydrology Tetsuo Kobayashi, Shuh Matsuda, Hideyuki Nagai & Jun’ichi Tesima 41

Impact of soil moisture movement schemes in a SVATS on the global climate of an AGCM Tosiyuki Nakaegawa & Masato Sugi 47

Estimation model for litter moisture content ratio on forest floor Koji Tamai 53

Development of the evaporation component for the physically-based distributed tank model Zongxue Xu, Jingyu Li & Kazumasa Ito 59

2 SVAT and Precipitation Runoff Modelling

Application of a land surface model for studying the role of boreal spruce forest in land surface–atmosphere interactions Olga N. Nasonova & Yeugeniy M. Gusev

65

Investigating the ability of a land surface model to simulate runoff on a large river basin scale Yeugeniy M. Gusev & Olga N. Nasonova 73

Large-scale modelling and spatial heterogeneity of landscape characteristics—experience from the Upper Danube River basin Joachim Geyer & Andreas H. Schumann 81

Toward improved parameter estimation of land surface hydrology models through the Model Parameter Estimation Experiment (MOPEX) John Schaake, Qingyun Duan, Victor Koren & Alan Hall 91

Hydrological modelling of the Mekong River basin Geoff Kite 99

A distributed dynamic parameters inverse model for rainfall–runoff Li Lan 103

Sub-grid runoff processes and hydrological modelling in the subarctic Canadian Shield Christopher Spence 113

3 Parameter Estimation for Large-Scale Hydrological Models

An analysis of the variation in hydrological conditions in the Korean peninsula due to global warming Yong Nam Yoon, Jae Soo Lee, Chulsang Yoo & Jae Hyun Ahn 119

Expanding distributed hydrological modelling to the continental scale Dawen Yang, Shinjiro Kanae, Taikan Oki & Katumi Musiake 125

A physically-based rainfall–runoff model and distributed dynamic hybrid control inverse technique Li Lan 135

Calibration of a global hydrological model against measured discharge Petra Döll, Frank Kaspar & Bernhard Lehner 143

Using conceptual hydrological modelling to develop better sub-grid variability in the Rossby Centre Regional Atmospheric Model L. Phil Graham, Göran Lindström, Björn Bringfelt, Marie Gardelin, Stefan Gollvik, Sten Bergström & Patrick Samuelsson 151

Daily river discharge prediction using GCM generated atmospheric data A. W. Jayawardena & S. P. P. Mahanama 159

A semi-distributed hydrological model and its application in a macroscale basin in China Shenglian Guo, Jinxing Wang & Jin Yang 167

Parameterization of sub-grid effects in a large-scale hydrological model Lev Kuchment 175

A completely-formed distributed rainfall–runoff model for the catchment scale Huaxia Yao & Michio Hashino 183

Coupled regional-scale hydrological–atmospheric model for the study of climate impact on Japan Junichi Yoshitani, M. L. Kavvas & Z.-Q. Chen 191

Spatially-distributed snowmelt, water balance and streamflow modelling for a large mountainous catchment: Boise River, Idaho, USA David C. Garen, Joachim Geyer, Andreas H. Schumann & Danny Marks 199

Influence de la nature et de l’origine des données sur la modélisation hydrologique de grands bassins versants en Afrique de l’Ouest M. Ouedraogo, J. E. Paturel, G. Mahé, E. Servat, A. Dezetter & D. Conway 209

4 Data Assimilation in Large-Scale Hydrological Models

Improved conditioning of SVAT models with observations of infrared surface temperatures M. F. McCabe, S. W. Franks & J. D. Kalma 217

Thermal remote sensing of the land surface for numerical weather prediction models S. W. Franks, S. R. McKee, J. D. Kalma, B. J. J. M. Van den Hurk & Yaping Shao 225

Contribution of satellite and lightning data to convective rainfall frequency analysis Maria Helena Ramos, Stephane Sénési, Jean-Dominique Creutin & Christophe Morel 233

Modelling the hydrological cycle of river basins using high resolution satellite information E. L. Muzylev & A. B. Uspensky 241

Assimilation of soil moisture in a hydrological model for flood forecasting A. Weisse, C. Michel, D. Aubert & C. Loumagne 249

Directives for 4-D soil moisture data assimilation in hydrological modelling E. E. van Loon & P. A. Troch 257

Incidence de l’incertitude pluviométrique sur la modélisation pluie–débit Radhia M’Chirgui, Zoubeida Bargaoui & András Bárdossy 269

Daytime long-wave radiation approximation for physical hydrological modelling of snowmelt: a case study of southwestern Ontario S. R. Fassnacht, K. R. Snelgrove & E. D. Soulis 279

Large-scale mapping of leaf area index using remote sensing data Takashi Ishii, Makoto Nashimoto & Hisashi Shimogaki 287

Regional extrapolation of meteorological data in a distributed hydrological model Vladimir Konovalov 291

5 Snow–Vegetation Interaction

Snow vegetation interactions: issues for a new initiative J. W. Pomeroy, P. Höller, P. Marsh, D. A.Walker & M. Williams 299

The impact of the representation of soil–vegetation–atmosphere interaction upon snow processes E. A. Kowalczyk & J. L. McGregor 307

Interactions of shrubs and snow in arctic tundra: measurements and models Joseph P. McFadden, Glen E. Liston, Matthew Sturm, Roger A. Pielke, Sr & F. Stuart Chapin, III 317

Hydrological modelling of river ice processes in cold regions Xieyao Ma, Yoshihiro Fukushima & Tetsuo Ohata 327

Estimating subsurface drainage from organic-covered hillslopes underlain by permafrost: toward a combined heat and mass flux model W. L. Quinton & D. M. Gray 333

Sublimation of snow intercepted by coniferous forest canopies in a climate model Richard Essery & John Pomeroy 343

Spatial fields of meteorological input data including forest canopy corrections for an energy budget snow simulation model David C. Garen & Danny Marks 349

Snow gliding and avalanches in a south-facing larch stand Peter Höller 355

The phenology of four subalpine herbs in relation to snow cover characteristics Christian Rixen, Veronika Stoeckli, Christine Huovinen & Kai Huovinen 359

A new possible site to study the effects of climate warming on tundra ecosystems: the Giant Mountains, Czech Republic Milena Kocianova & Helena Štursova 363

Key word index 369

Abstracts Publ. 270________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 3–10.

Relative influence of vertical and horizontal processes in large-scale water and energy balance modelling

ELEANOR BLYTHCentre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UKe-mail: [email protected]

Abstract The role of large-scale land-atmosphere transfer schemes is to partition the massive radiative energy from the sun into evaporation and sensible heat. In order to do so, the models need to trace where the radiation energy is being absorbed and how much water is available at the point of absorption. Therefore, great emphasis has been placed on the vertical structure of the land surface and on the vertical movement of water through the soil and the vegetation system. As part of this tracking of the vertical movement of water, there is a necessity to include some representation of the horizontal flow of water. If this is ignored, the land is assumed to be flat and homogeneous, and no surface runoff will be generated, resulting in modelled soil moisture, and hence evaporation, that is too high. This is partly why hydrological models are more commonly being embedded in meteorological land surface schemes. The other reason is that the runoff itself is now required for the purposes of predicting water resources, freshwater flows into the oceans and for model validation using river flow. There is a need to assess how complex these hydrological models need to be. On the one hand, they need to be complex enough to model the processes accurately. On the other hand, the accuracy of the model needs to be weighed against the overhead of obtaining parameters on a global scale. This paper attempts to address this issue by comparing the sensitivity of the desired output (long-term water and energy balance) to the parameters in the horizontal and vertical models. The land surface scheme of the Met Office (Met Office Surface Energy Scheme—MOSES) is used with a standard rainfall–runoff model, Probability Distribution Model (PDM) embedded in the top soil layer. The parameters of the vertical process model are varied from a coarse soil to a fine soil. The parameter for the horizontal process model is varied from a flat homogeneous landscape to one with high variability. It is shown that the long-term water balance in this model is equally sensitive to parameters that describe the horizontal flow of water and the vertical flow of water. Key words land surface schemes; water balance; hydrological model; soil parameters

________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 143–149.

Calibration of a global hydrological model against measured discharge

PETRA DÖLL, FRANK KASPAR & BERNHARD LEHNERCenter for Environmental Systems Research, University of Kassel, D-34109 Kassel, Germanye-mail: [email protected]

Abstract The hydrological model WaterGAP 2, a global model of water availability and water use, is calibrated against time series of annual discharge measured at 724 stations, by adjusting the runoff coefficient in the respective upstream areas. The reduction of natural discharge by consumptive water use is simulated by the model in at least an approximate manner; otherwise, a comparison of modelled and measured discharges would not be possible, particularly in basins

with extensive irrigation. The calibration basins cover 50% of the global land area excluding Greenland and Antarctica. For 327 stations, the calibrated runoff coefficients remain within physically plausible limits, and the model efficiency measured by the Nash-Sutcliffe coefficient is mostly satisfactory to good. The measured long-term average discharge in the other basins can only be computed if a runoff correction factor is introduced. This is due to both uncertain input data (e.g. underestimated precipitation in snow-dominated areas) and inappropriate model formulation (e.g. neglecting the loss of river water in semiarid areas). Key words hydrological model; water use model; global model; calibration; discharge; consumptive water use; precipitation correction

________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp.11–18.

The representation of the seasonal hydrological cycle in a regional climate model in west Europe

A. J. DOLMAN, M. SOET Alterra, PO Box 46, 6700 AA Wageningen, The Netherlandse-mail: [email protected]

B. J. J. M. VAN DEN HURK Royal Dutch Meteorological Institute, PO Box 201, 3730 AE De Bilt, The Netherlands

R. J. M. IJPELAAR & R. J. RONDADepartment of Meteorology and Air Quality, Wageningen University, Duivendaal 2, 6701 AP Wageningen, The Netherlands

Abstract Soil moisture is key to adequate prediction of near surface temperature and humidity in climate models. To improve the performance of the hydrological cycle in a regional climate model (RACMO) a series of experiments was performed with one-dimensional land surface models. The starting point for these experiments was the ECMWF land surface model. Detailed comparison with a multi-layer process-based SVAT model, SWAP, showed particular sensitivity to the parameterization of soil hydraulic properties and rooting depth when compared with data. A new gridded soil map was produced for inclusion in the regional climate model. This map was used in a 3-D regional climate model RACMO. Comparison with the old parameterization of the model showed changes in the water balance that differed by region and were primarily determined by changes in saturated conductivity.Key words west Europe; RACMO; hydrological cycle; climate model; soil hydraulic properties


Sublimation of snow intercepted by coniferous forest canopies in a climate model

RICHARD ESSERYHadley Centre for Climate Prediction and Research, Met Office, London Road, Bracknell RG12 2SY, UKe-mail: [email protected]

mailto:[email protected]

JOHN POMEROYCentre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth SY23 3DB, UK

Abstract Using a tiled representation of land surfaces allows a direct estimation of how much snow sublimates from forest canopies in a climate model. Observations suggest that 25–45% of the annual snowfall can sublimate from coniferous canopies in cold, dry continental environments. A similar range of simulated sublimation fractions is found for the forested fractions of continental gridboxes, but the sublimation is likely to be overestimated in maritime environments due to the neglect of canopy snow unloading.Key words boreal forest; climate simulation; mosaic; snow interception; sublimation


Daytime long-wave radiation approximation for physical hydrological modelling of snowmelt: a case study of southwestern Ontario

S. R. FASSNACHTDepartment of Hydrology and Water Resources, University of Arizona, Tucson, Arizona 85721-0011, USA e-mail: [email protected]

K. R. SNELGROVE & E. D. SOULISDepartment of Civil Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

Abstract Since incoming long-wave radiation is not routinely measured in Canada, when it is required as a meteorological parameter, such as input to a physically-based hydrological model, the data must be derived. These data have been successfully computed as a function of near surface air temperature and cloud cover. However, cloud cover data are also not routinely measured. A method is described to compute the cloud cover fraction, for use to estimate the long-wave radiation, from a comparison of measured to theoretical short-wave radiation at three sites in central southwestern Ontario. The daytime cloud cover fraction is on average slightly more than 0.50. The impact of different long-wave radiation estimates from varying cloud cover fraction assumptions is illustrated in terms of simulated streamflow resulting from snowmelt.Key words incoming long-wave radiation; short-wave radiation; snowmelt modelling; cloud cover


Thermal remote sensing of the land surface for numerical weather prediction models

S. W. FRANKS, S. R. McKEE, J. D. KALMADepartment of Civil, Surveying and Environmental Engineering, University of Newcastle, Callaghan 2308, New South Wales, Australiae-mail: [email protected]

B. J. J. M. VAN DEN HURK Atmospheric Research Division, Royal Netherlands Meteorological Institute(KNMI), 3730 AE De Bilt, The Netherlands

YAPING SHAOCEMAP, School of Mathematics, University of New South Wales, Sydney 2052, New South Wales, Australia

Abstract Soil–vegetation–atmosphere transfer (SVAT) models provide the lower boundary for numerical weather prediction (NWP) models and general circulation models (GCM). Typically, these models are not parameterized with reference to actual measured land surface behaviour, but have parameters specified according to approximate and simplified concepts of land surface type. Spatial variability of processes and fluxes coupled with uncertainty in input rainfall mean that significant uncertainty should be associated with land surface models used in NWP models. In this paper, an assimilation approach—thermal remote sensing—is advocated; whilst subject to some uncertainty, it may be usefully employed to update land surface models, addressing issues of both parameter and input rainfall uncertainty.Key words SVAT modelling; NWP modelling; land surface fluxes; thermal remote sensing; assimilation; heating rates


Spatially-distributed snowmelt, water balance and streamflow modelling for a large mountainous catchment: Boise River, Idaho, USA

DAVID C. GARENUnited States Department of Agriculture, Natural Resources Conservation Service, National Water and Climate Center, 101 SW Main Street, Suite 1600, Portland, Oregon 97204-3224, USAe-mail: [email protected]

JOACHIM GEYER, ANDREAS H. SCHUMANNLehrstuhl für Hydrologie, Wasserwirtschaft und Umwelttechnik, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany

DANNY MARKSUnited States Department of Agriculture, Agricultural Research Service, Northwest Watershed Research Center, 800 Park Boulevard, Plaza IV, Suite 105, Boise, Idaho 83712-7716, USA

Abstract As a demonstration of the potential of spatially-distributed hydrological modelling for large catchments in mountainous areas, a snow simulation model and a water balance/streamflow model have been linked together and applied to a 2150 km2 portion of the Boise River catchment in Idaho, USA. The snow model simulates all of the energy fluxes into and out of the snowpack and requires spatial field time series of all of the major meteorological inputs. It is being run at 250 m grid resolution with a 3-h time step. The output spatial fields of this model are aggregated in space and time and are used as input to the water balance model. The water balance model simulates all of the major land surface processes using algorithms that are physically based but are constructed so as to be appropriate for this large spatial scale. It makes extensive use of geographic information systems for parameterization. The model operates on a daily time step and can have a variable cell size; for the Boise River, a 1 km 2 grid cell size is being used. These models are intended to address water and natural resource management issues, but the concepts of finding appropriate mathematical formulations and of matching the modelling scale with the process scale have broader significance.Key words spatially-distributed hydrological modelling; snowmelt; energy balance; water balance; streamflow; geographic information systems; Boise River, Idaho, USA

________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS

Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 349–353.

Spatial fields of meteorological input data including forest canopy corrections for an energy budget snow simulation model

DAVID C. GARENUnited States Department of Agriculture, Natural Resources Conservation Service, National Water and Climate Center, 101 SW Main Street, Suite 1600, Portland, Oregon 97204-3224, USAe-mail: [email protected]

DANNY MARKSUnited States Department of Agriculture, Agricultural Research Service, Northwest Watershed Research Center, 800 Park Boulevard, Plaza IV, Suite 105, Boise, Idaho 83712-7716, USA

Abstract Methods of computing spatial fields of meteorological inputs for a spatially distributed energy budget snow simulation model have been developed and applied to the Boise River catchment in Idaho, USA. Fields at a 250 m resolution and a 3-h time step have been computed for precipitation, air temperature, dew point temperature, wind speed and solar and thermal radiation using observations at up to eight meteorological stations in and near the catchment. Various methods of interpolating or distributing the values are used depending on the variable and the data available. In addition, corrections to solar and thermal radiation fields are made to account for the effects of the forest canopy.Key words snow modelling; energy budget; spatial fields; meteorological data; solar radiation; forest canopy


Large-scale modelling and spatial heterogeneity of landscape characteristics—experience from the Upper Danube River basin

JOACHIM GEYER & ANDREAS H. SCHUMANNInstitute for Hydrology, Water Management and Environmental Engineering, Ruhr-University Bochum, Universitätsstraße 150, D-44780 Bochum, Germanye-mail: [email protected]

Abstract This study presents the application of a SVAT model for the design of a macroscale hydrological model. For a climate change study, a large number of scenarios is used to assess the risk of changes in runoff conditions for the Upper Danube basin (~4000 km2). The paper emphasizes the adequate derivation of the spatial structure of the catchment, which has to fulfil two requirements. On the one hand, the spatial variability of the catchment characteristics has to be obtained to allow a physically-based representation of the relevant hydrological processes. On the other hand, the number of spatial units that can be considered is very limited, owing to the computational effort caused by the huge number of scenarios. Consequently, the most important catchment characteristics, which govern the spatial variation of the relevant hydrological processes, have to be identified. The derivation of a ranking of characteristics regarding their influence on different processes is presented in the case study.Key words macroscale modelling; spatial units; catchment characteristics; sensitivity analysis; Danube basin


Using conceptual hydrological modelling to develop better sub-grid variability in the Rossby Centre Regional Atmospheric Model

L. PHIL GRAHAM, GÖRAN LINDSTRÖM, BJÖRN BRINGFELT, MARIE GARDELIN, STEFAN GOLLVIK, STEN BERGSTRÖMSwedish Meteorological and Hydrological Institute, S-60176 Norrköping, Swedene-mail: [email protected]

PATRICK SAMUELSSONDepartment of Meteorology, Stockholm University, S-10691 Stockholm, Sweden

Abstract To address deficiencies in the treatment of sub-grid processes in the Rossby Centre Regional Atmospheric Model (RCA), the variability parameter approach for soil moisture from conceptual hydrological modelling was introduced to the RCA model. This improves representation of sub-grid soil moisture variability. Relationships between fraction of snow cover and snowpack volume from hydrological modelling experience were formulated and introduced to the snow accumulation and depletion calculations in the RCA model. These changes reduce the sub-grid variability of these processes to a statistical representation of the variability in each grid square. This provides a varied distribution of soil moisture and snowpack over each atmospheric model grid and produces a gradually increasing runoff response with increasing soil moisture.Key words land surface; sub-grid variability; hydrological modelling; HBV model; atmospheric modelling; soil moisture; snow


A semi-distributed hydrological model and its application in a macroscale basin in China

SHENGLIAN GUO, JINXING WANG & JIN YANGCollege of Water Resources and Hydropower, Wuhan University, Wuhan 430072, Chinae-mail: [email protected]

Abstract A semi-distributed monthly water balance model is proposed and developed to simulate and predict hydrological processes and water resources. Geographical Information System techniques are used as a tool to analyse topography, river network, land use, human activities, and vegetation and soil characteristics. The model parameters are linked with these basin charac-teristics by the regression and optimization methods. A parameterization scheme is developed and the model parameters are estimated for each grid. Based on the different general circulation model (GCM) and regional climate model (RCM) outputs, the sensitivities of hydrology and water resources to global warming are studied. It is found that the proposed models are capable of producing both the magnitude and timing of runoff and soil moisture conditions, for modelling sustainable water resources development. Key words water balance model; macroscale basin; GIS techniques; runoff simulation; runoff prediction; climate change impact assessment

________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp.73–79.


Investigating the ability of a land surface model to simulate runoff on a large river basin scale

YEUGENIY M. GUSEV & OLGA N. NASONOVAWater Problems Institute, Russian Academy of Sciences, Gubkina St. 3, Moscow 117971, Russiae-mail: [email protected]

Abstract The aim of the present work is to investigate the ability of the physically-based land surface model SWAP-2 (Soil–Water–Atmosphere–Plants) to simulate runoff on a large river basin scale, and to reveal the potentials for model improvement. The model treats heterogeneity of a large basin explicitly, i.e. it divides the basin into a number of computational units provided with deterministic effective values for land surface parameters and atmospheric forcings. The SWAP-2 model was validated against naturalized streamflow from 15 drainage catchments located within the Red-Arkansas River basin for the period 1979–1988. The accuracy of the model was found to be close to the estimated maximum accuracy under the chosen discretiza tion of drainage basins and prescribed effective input data. The SWAP-2 model does not incorporate significant systematic error into the results and can operate at a regional scale with satisfactory accuracy under appropriate discretization of a basin without calibration of its land surface parameters.Key words land surface model; runoff; Red-Arkansas River basin; regional-scale modelling


Snow gliding and avalanches in a south-facing larch stand

PETER HÖLLER Institute for Avalanche and Torrent Research, Federal Forest Research Centre, Rennweg 1, A-6020 Innsbruck, Austria e-mail: [email protected]

Abstract Release zones of avalanches are common in forests sites, especially in low density stands near the timberline. Observations showed that slab avalanches (caused by weak layers like surface or depth hoar), as well as glide avalanches, are possible in larch stands with a low canopy density. The main condition for the formation of glide avalanches in forest sites is a strong increase in the rates of snow gliding. This investigation shows that snow gliding is strongly influenced by the forest canopy. Less dense forest canopies were associated with higher snow glide rates. The total distance of snow gliding in the dense forest did not exceed 100 mm; however, total gliding in forest clearings reached values up to 1700 mm. Gliding is more frequent in winter periods with deep snow and less frequent in those years where the snow depth was below average. Snow gliding in forests increases over February, March and April; but there is no gliding in January because of low snow temperatures.Key words snow gliding; glide avalanches; forest cover


Large-scale mapping of leaf area index using remote sensing data

TAKASHI ISHII, MAKOTO NASHIMOTO & HISASHI SHIMOGAKICentral Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba-ken 270-1194, Japane-mail: [email protected]

Abstract The estimation of forest leaf area index (LAI) based on satellite data was evaluated. We compared direct and indirect LAI measurements for two softwood plantations to examine the applicability of the indirect method. Comparison of the normalized difference vegetation index (NDVI) based on satellite data with the LAI based on the indirect method shows a good relationship for a broad range of LAI values. An LAI map of Japan estimated from NOAA data largely coincides with published data for all of Japan.Key words remote sensing; leaf area index; vegetation index; phenology


Daily river discharge prediction using GCM generated atmospheric data

A. W. JAYAWARDENA Department of Civil Engineering, The University of Hong Kong, Hong Konge-mail: [email protected]

S. P. P. MAHANAMAGoddard Earth Science Technology Centre, NASA/Goddard Space Flight Centre, Greenbelt, Maryland 20771, USA

Abstract An attempt to simulate daily river discharges in Mekong and Chao Phraya river basins from macroscale atmospheric data is presented. Atmospheric data for the studies were taken from International Satellite Land Surface Climatology Project (ISLSCP) CD-ROMs and field observa-tions. Land surface hydrology was modelled using the variable infiltration capacity (VIC) model. A modified soil moisture infiltration capacity variation curve was used in the study.Key words GCM generated atmospheric forcings; VIC model; modified Xinanjiang model; Mekong River; Chao Phraya River, Thailand


Hydrological simulation by SiB2-Paddy in the Chao Phraya River basin, Thailand

WONSIK KIM, YASUSHI AGATA, SHINJIRO KANAE, TAIKAN OKI & KATUMI MUSIAKEInstitute of Industrial Science, University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505, Japane-mail: [email protected]

Abstract As a part of the GEWEX Asian Monsoon Experiment in the tropics (GAME-T), water and energy balances were estimated by simulations of the modified version of the Simple Biosphere Model (SiB2) using the International Satellite Land Surface Climatology Project (ISLSCP) forcing data for the Chao Phraya River basin, Thailand. Four simulations with/without applying realistic vegetation type and with/without incorporated paddy scheme were carried out,


and the results were compared with the observed discharge data at Nakhon Sawan gauging station where the basin size is 110 569 km2. Using the revised SiB2, simulated annual runoff compared well with the observations, when the flow controls by major two dams are considered, and the annual water balance is also well reproduced by the SiB2 simulation. In terms of energy balance, differences of each simulation result are not conspicuous. The ratio of latent heat flux to net radiation in the dry season is no lower than that of the wet season, which is concordant with the observational results. From the analysis of model calculations, this is due to the increase in transpiration from vegetation using soil moisture.Key words GAME-Tropics; Simple Biosphere model (SiB2); runoff; energy balance; water balance; paddy


Hydrological modelling of the Mekong River basin

GEOFF KITEBryn Eithyn, Cefn Bychan Road, Pantymwyn, Mold CH7 5EN, UK

Abstract The many wetlands along the Mekong River, including Cambodia’s Tonle Sap (Grand Lac), are major sources of fish for the riparian peoples and an important part of the regional economy. This resource may be affected by the development of dams and diversions in the basin. The Semi-Distributed Land-Use Runoff Process (SLURP) hydrological model has been applied to the basin. First, only data from the Internet and from public-domain databases were used to provide a comprehensive simulation of the daily hydrological cycle for the main river and tributaries. Simulating the complex hydraulics of the river connecting the Tonle Sap and the Mekong required local data to develop routing relationships. The model takes into account river diversions and dams where data are available. Model outputs can be used to investigate water allocations and the effects of land-use change or climate change on water resources, to evaluate the effects of proposed structures on fisheries and environmental interests and on the performance of irrigation schemes.Key words Mekong River basin; hydrology; SLURP model; fish; dams


A bucket with a bottom hole (BBH) model of soil hydrology

TETSUO KOBAYASHIFaculty of Agriculture, Kyushu University, Hakosaki 6-10-1, Fukuoka 812-8581, Japane-mail: [email protected]

SHUH MATSUDANational Research Institute of Agricultural Engineering, Tsukuba 305-8609, Japan

HIDEYUKI NAGAIInstitute for Hydrospheric–Atmospheric Sciences, Nagoya University, Nagoya 464-8601, Japan

JUN’ICHI TESIMAKyushu Branch, Japan Weather Association, Fukuoka 810-0052, Japan

Abstract An improved version of the bucket model of soil hydrology with seven parameters, which permits not only downward but also upward water movement across the bottom, is constructed. This model is validated by comparing with actual soil moisture data.Key words bucket model; soil moisture; evapotranspiration; gravity drainage


A new possible site to study the effects of climate warming on tundra ecosystems: the Giant Mountains, Czech Republic

MILENA KOCIANOVA & HELENA ŠTURSOVAKrkonose National Park Administration, 543 11 Vrchlabi, Czech Republice-mail: [email protected]

Abstract In the north–south transect between the tundra areas of northern Sweden (Abisko), across southern Norway (Dovrefjell) to the Alps, one may include the summit area of the Giant Mountains (Czech Republic—Krkonoše in Czech and Poland—Karkonosze in Polish), which constitutes an isolated island of arctic-alpine tundra within the Central European Sudetes. Its area was strongly influenced, like the Scandinavian and Alps areas, by periglacial conditions during the Ice ages in the Pleistocene era. At present, the average annual air temperature of the Giant Mountains tundra area is about 2.6–5.7°C higher than that of the Abisko area and 1.8°C higher than that of Dovrefjell. The intensity of frost processes is impressively lower and special palsa-like forms have been recognized in seasonally freezing peat bogs, where some arctic-alpine plant species survive in marginal conditions in the Giant Mountains. Therefore the Giant Mountains could be used to study the effects of long-term natural climate warming on some Scandinavian tundra ecosystems. Scandinavian tundra conditions seem to be similar to those existing in Central Europe 10 000 years ago; therefore Scandinavian areas appear very interesting with regard to the beginning of postglacial development of tundra areas in Central Europe. Key words tundra; Giant Mountains, Czech Republic; Abisko, Sweden; Dovrefjell, Norway; climate; vegetation; palsas


Regional extrapolation of meteorological data in a distributed hydrological model

VLADIMIR KONOVALOV Central Asian Hydrometeorological Research Institute, 72 K. Makhsumov Street, 700052 Tashkent, Uzbekistane-mail: [email protected]

Abstract The following tasks are considered: (a) obtaining the regional dependencies for climatic norms of air temperature, precipitation and humidity as functions of altitude, latitude and longitude; (b) preparing a regional information database; and (c) developing a method of extrapolation of long-term series of temperature, precipitation and humidity measurements on a basic network into arbitrary points in the Central Asian region. The estimated quality of computed long-term series of precipitation, humidity and air temperature at fourteen control points turned out to be satisfactory. Key words Central Asia; computation; spatial extrapolation; meteorological data



The impact of the representation of soil–vegetation–atmosphere interaction upon snow processes

E. A. KOWALCZYK & J. L. McGREGOR CSIRO Atmospheric Research, Private Bag No. 1, Aspendale, Victoria 3195, Australia e-mail: [email protected]

Abstract Two soil–vegetation–atmosphere transfer (SVAT) schemes, with different degrees of complexity, were incorporated into the CSIRO Division of Atmospheric Research Limited Area Model (DARLAM). Both schemes were used to compute the spatial and temporal evolution of fluxes of momentum, energy and water, as well as snow accumulation, ablation, runoff, and soil freezing in a region of high latitude. Both schemes use the same treatment for soil subsurface thermal and hydrological processes, as well as for snow. In the first SVAT scheme, a “big-leaf'” approach is used to represent vegetation. Each computational grid box is partitioned into a vegetation part and a bare ground part; the model computes the fluxes for each fraction separately, with no aerodynamic or radiative interaction between the vegetation and the ground. In the second scheme, the vegetation is spread across the grid and placed above the ground, allowing for full interaction; a combined energy balance is calculated for the whole system. The soil model solves Richards’ equation for moisture transport over six soil layers. Similarly, a six-layer model is used to compute heat conduction. A parameterization of a soil freeze/thaw cycle is also included in the model. The snow model computes the temperature, snow density and thickness of three snowpack layers. The experiment consists of two 2-year integrations, forced at the lateral boundaries by NCEP reanalyses. The results are presented for soil–vegetation–atmosphere interaction, in regards to the calculation of snow processes and surface fluxes. Key words snow processes; vegetation processes; vegetation parameters; SVAT schemes; atmospheric model; limited area model; computer simulation; snow–atmosphere exchange


Parameterization of sub-grid effects in a large-scale hydrological model

LEV KUCHMENTWater Problems Institute, Russian Academy of Sciences, Gubkin St. 3, Moscow 117971, Russiae-mail: [email protected]

Abstract The methods of parameterization of sub-grid effects and their effectiveness are investigated using a distributed physically-based model of the hydrological cycle for two river basins situated in the steppe-forest zone of Russia. To estimate the sub-grid effects, it is assumed that these values are stochastic fields and two-parameter statistical distributions are used to describe variations of these characteristics inside the grid domain. Different assumptions on the change of the coefficient of spatial variation depending on the size of grid domain and the magnitude of characteristic under consideration were tested. It is shown that the dependence of the spatial variance of snow cover on the size of area can be obtained on the basis of the hypothesis of statistical self-similarity and the application of this dependence can essentially improve snowmelt runoff modelling. The rainfall, runoff and basin-averaged evapotranspiration are sensitive to the procedure of accounting for the sub-grid variation of saturated hydraulic conductivity and stomatal


resistance, but the scaling of these parameters has comparatively small influence on the hydrographs.Key words runoff; modelling; hydrological cycle; sub-grid effects; parameterization


A distributed dynamic parameters inverse model for rainfall–runoff

LI LANHydrology and Water Resources Department, Hydraulic and Water Electric Engineering Institute, Wuhan University, Wuhan 430072, Chinae-mail: [email protected]

Abstract A distributed and dynamic parameters inverse technique is proposed, by which a physics-based rainfall–runoff model is based on hillslope hydrology, soil moisture and groundwater hydrodynamics, and open-channel hydraulics together with mathematical physical inverse theory. The model couples one-dimensional transient subsurface flow (soil evaporation, saturated and unsaturated soil water flow), and one-dimensional unsteady overland flow (vegetation interception, infiltration, evaporation and transpiration), with groundwater flow (infiltration and evaporation). The inverse model allows spatial distribution and time diversification in the hillslope, soil moisture and groundwater physical characteristics, including vegetation interception, infiltration, evaporation, soil hydraulic conductivity, overland flow wave speed, subsurface flow wave speed, groundwater wave speed, etc. Using the inverse formulas of the physical variables and parameters provides a dynamic, distributed, nonlinear, and stabilized model. The model uses a finite difference solution method with a mathematical physical inverse method. The model and inverse technique have been applied to three sub-basins within Feng Man Reservoir basin, China. The results indicated that the inverse technique works quite well in rainfall–runoff simulation for large and medium catchments using 33 years of flood season hydrological records from the mouth of the channel. Key words rainfall–runoff model; inverse technique; finite difference method; Feng Man Reservoir catchment; pulse spectrum method; flood season


A physically-based rainfall–runoff model and distributed dynamic hybrid control inverse technique

LI LAN Hydrology and Water Resources Department, Hydraulic and Water Electric Engineering Institute, Wuhan University, Wuhan 430072, Chinae-mail: [email protected]

Abstract In this paper a physics-based rainfall–runoff model is developed utilizing an inverse technique based on hillslope hydrology, soil humidity and groundwater hydrodynamics, open-channel hydraulics theory and mathematical physical inverse problem theory. The model couples equations of two-dimensional transient subsurface flow, one-dimensional unsteady overland flow, one-dimensional groundwater flow, and one-dimensional channel flow. The inverse model allows for the spatio-temporal variation and parameters in hillslope, soil humidity, groundwater physical characteristics, and channel flow including vegetation interception, infiltration, evaporation, soil

hydraulic conductivity, overland flow wave speed, subsurface flow wave speed, groundwater wave speed, stream wave speed and diffuse coefficient, etc. How to obtain the total unit-width discharge data from overground and underground flow to the channel becomes a key question in deciding whether or not to apply a physically-based mathematical model. A physically-based distributed hybrid control inverse model for rainfall–runoff is demonstrated by an application of a distributed and dynamic parameters inverse technique. The hybrid control technique (HCT) is proposed utilizing physics-based open-channel hydraulics and the mathematical physical inverse approach. The inverse solution provides a dynamic, distributed, nonlinear, and stable result. The model uses a finite difference method and a mathematical physical inverse method. The proposed HCT can represent the unit-width discharge process. The model and inverse technique have been applied to three sub-watersheds (of 52 200, 108 500 and 250 000 ha) within the Feng Man Reservoir catchment in China. There was generally good agreement between observed and simulated responses in all parts of the catchment , through the use of inverse parameters, upstream flow and total unit-width discharge. The results indicate that the inverse technique works quite well in flood flow simulation using 33 years of flood season hydrological records at the mouth of the channel. Key words hybrid control technique; inverse technique; finite difference method; Feng Man Reservoir catchment; pulse spectrum method; physically-based rainfall–runoff model


Hydrological modelling of river ice processes in cold regions

XIEYAO MAInstitute for Global Change Research, 3173-25 Showamachi, Kanazawa-ku, Yokohama, Japane-mail: xyma@ jamstec.go .jp

YOSHIHIRO FUKUSHIMA Research Institute for Humanity and Nature, Oiwake-cyo, Kita-shirakawa, Sakyo-ku, Kyoto 606-8502, Japan

TETSUO OHATAThe Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan

Abstract River ice covers for the Lena River basin are simulated using a simple accumulated degree-day method from October 1986 to September 1987, which is equal to the period of hydrological modelling of the basin without river ice process. The forcing data are routine daily meteorological data and river water temperature data. The result shows that estimated ice cover breakup dates are consistent with those observed for 60% of the 51 river sections in the Lena River basin. It is expected that the simulations of hydrological processes in cold regions will become more reasonable by linking ice cover estimates into river routing models. Key words Lena River basin, Siberia; hydrological modelling; river ice growth and decay; ice cover breakup date


Improved conditioning of SVAT models with observations of infrared surface temperatures

M. F. McCABE, S. W. FRANKS & J. D. KALMADepartment of Civil, Surveying and Environmental Engineering, University of Newcastle, Callaghan 2308, New South Wales, Australiae-mail: [email protected]

Abstract This paper reports on the use of an observed record of infrared surface temperature in conditioning SVAT model predictions of evapotranspiration. An investigation into whether such a time series can be employed to provide information on the dynamics of the land surface is presented. It is shown that calibration of modelled fluxes to observed responses of latent and sensible heat provides some constraint on model predictions. Significantly, calibrating the model to observations of the surface temperature showed constraint in estimates of cumulative evapotranspiration and also in the reproduction of the observed latent heat record. This result demonstrates that measurements of infrared temperature have some potential in improving the ability of land surface models to characterize surface heat fluxes. Using the infrared surface temperature records required some modification and the concept of a temperature difference approach is examined. Key words evapotranspiration; surface temperature; calibration; SVAT model; land surface flux


Interactions of shrubs and snow in arctic tundra: measurements and models

JOSEPH P. McFADDEN & GLEN E. LISTONDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USAe-mail: [email protected]

MATTHEW STURMUS Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, Alaska 99703, USA

ROGER A. PIELKE, SRDepartment of Atmospheric Science, Colorado State University, Fort Collins, Colorado 80523, USA

F. STUART CHAPIN, IIIInstitute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA

Abstract In arctic tundra, where wind transport of snow is common, shrubs can significantly modify the distribution and physical characteristics of the snow cover. We examined interactions between shrubs and snow by measuring snow depths along three 1-km transects in arctic Alaska and then measuring plant canopy characteristics at the same locations during the following growing season. Snow depths correlated closely with shrub canopy height and stem diameter. Shrubs increased snow depths by 27%, independent of local variations in topographic relief. We also used a snow-transport and energy-balance snowmelt modelling system to perform a series of simulations over a 4 km2 domain near the field site. A shrub increase was simulated by replacing the current tussock and wet tundra vegetation types with shrub tundra. The shrub expansion increased the domain-averaged snow depth by 20% and decreased blowing-snow sublimation fluxes by 60%. The snow cover change affected the timing and magnitude of all surface energy balance components during the melt, and increased runoff late in the snowmelt period. Shrubs increased snow accumulation by an amount approximately equal to the fraction of the total winter snowfall that is normally lost to sublimation, suggesting that an increase in shrub cover could

significantly increase snow depths in the region, even without an increase in precipitation.Key words sublimation; runoff; energy balance; evaporation; Alaska


Incidence de l’incertitude pluviométrique sur la modélisation pluie–débit

RADHIA M’CHIRGUI, ZOUBEIDA BARGAOUIEcole Nationale d’Ingénieurs de Tunis, BP 37, 1002 Tunis, Tunisie e-mail: [email protected]

ANDRÁS BÁRDOSSY Institut für Wasserbau, Universität Stuttgart, Pfaffenwaldring 61, D-70550 Stuttgart, Allemagne

Résumé Le modèle hydrologique HBV (Bergström, 1992), modèle conceptuel distribué, est appliqué à l’estimation des débits moyens journaliers du bassin versant de l’oued Tessa (Tunisie), au niveau d’une station hydrométrique contrôlant une superficie de 1950 km2. La pluviométrie, connue à travers un réseau de 26 stations, est de 460 mm an -1 en moyenne inter-annuelle. L’écoulement moyen inter-annuel est de 74 Mm3. L’objectif du présent article est de caractériser l’incidence de l’incertitude liée à la pluviométrie, sur les débits simulés par le modèle. Nous considérons d’une part, l’incertitude liée à la qualité des données pluviométriques, d’autre part celle relative à l’interpolation spatiale de la pluie. Dans une première étape, le contrôle des données hydro-pluviométriques est réalisé en examinant la relation pluie–débit à l’échelle de l’événement: concomitance des crues sur le bassin, réponse du bassin aux précipitations, comparaison des lames écoulées et précipitées, de façon à dégager les événements douteux ou incertains. L’interpolation des champs pluviométriques pour les différentes averses adopte la méthode du krigeage. Nous montrons dans une deuxième étape que les variogrammes obtenus à partir des champs krigés sont marqués par un palier plus faible que celui caractérisant les variogrammes issus des observations. Le krigeage opère ainsi un lissage pouvant conduire, s’il était suffisamment fort, à une sous-estimation des débits simulés. Alternativement, la méthode proposée consiste alors à générer des champs pluviométriques par simulation conditionnelle et à calculer les débits résultants pour chaque simulation. Cette méthodologie est appliquée pour un seul événement, identifié comme douteux lors de la première étape. La distribution de probabilité empirique des débits générés sur les 19 simulations effectuées montre que la probabilité au non dépassement de la lame écoulée observée est de 0.85, ce qui semble valider les observations. Mots clefs modèle pluit–débit; incertitude; krigeage; pluie; simulation conditionnelle; modèle HBV; validation de données hydro-pluviométriquesKey words rainfall–runoff model; uncertainty; kriging; rainfall; conditional simulation; HBV model; validation of hydro-pluviometric data


Modelling the hydrological cycle of river basins using high resolution satellite information

E. L. MUZYLEV Water Problem Institute, Russian Academy of Sciences, 3 Gubkin Street, Moscow 117735, Russia e-mail: [email protected]

A. B. USPENSKY Scientific and Research Center on Space, Hydrometeorology & Planets, Roshydromet, 7 Bolshoy Predtechensky, Moscow 123242, Russia

Abstract The results of modelling the hydrological cycle (HC) for river basins using satellite-based land surface temperature (LST) fields are presented. The HC model describes vertical moisture and heat transfer in the soil–plant–atmosphere system, as well as overland flow formation and flow in river networks, and allows one to estimate the effect of large- and small-scale land surface heterogeneities. It is applied to the Seim River basin with a watershed area of 7460 km2 situated in the forest–steppe zone of Central Russia (Kursk Region). The satellite LST estimates were used to validate the model and to specify the initial conditions. The retrieval of LST fields from cloud-free NOAA-AVHRR data is performed using a technique which is based on the split-window method. It is shown that using satellite LST retrievals provides improved model results. Key words hydrological cycle model; evapotranspiration; land surface temperature; AVHRR data; split-window algorithm; emissivity; vegetation index


Impact of soil moisture movement schemes in a SVATS on the global climate of an AGCM

TOSIYUKI NAKAEGAWA & MASATO SUGIMeteorological Research Institute, Japan Meteorological Agency, 1-1 Nagamine, Tsukuba, Ibaraki 305-0052, Japane-mail: [email protected]

Abstract Five numerical simulations with different versions of the schemes of soil moisture movement are conducted with the Meteorological Research Institute Global Spectral Model coupled with an improved Simplified Biosphere model to identify their effect on the model climate. One simulation with a new surface infiltration scheme improved the model’s climate not only in the soil but also in the atmosphere, while the other experiments affected that in the soil only. The stronger persistence of the soil moisture anomaly at the third layer sustains a recycling system between evaporation and precipitation through soil water storage during a dry period, which improved the climate of the model. This study emphasizes the importance of the partition of precipitation into surface runoff and infiltration as well as that of the net radiation into latent heat and sensible heat at the Earth’s surface.Key words soil moisture movement; global climate; persistence; recycle; partition


Application of a land surface model for studying the role of boreal spruce forest in land surface–atmosphere interactions

OLGA N. NASONOVA & YEUGENIY M. GUSEVWater Problems Institute, Russian Academy of Sciences, Gubkina St. 3, 117971 Moscow, Russiae-mail: [email protected]

Abstract The aim of this paper is to study the impact of boreal spruce forest on heat and water exchange between the land surface and the atmosphere by means of an advanced land surface model SWAP, which adequately treats the energy balance and hydrology of boreal forests and non-forested areas. The work is based on model results and observations obtained during 18 years (1966–1983) at the Tayozhniy catchment (covered by boreal forest, mainly composed of spruce) and the Usadievskiy catchment (grassland), both situated in the central part of the Valdai Hills, Russia. The results of model simulations for the forested and non-forested catchments were compared to reveal the role of the spruce forest in land surface–atmosphere interactions. The main emphasis was on the cold season processes, since these have received less attention in land surface modelling. Key words boreal spruce forest; land surface model; water balance components


Influence de la nature et de l’origine des données sur la modélisation hydrologique de grands bassins versants en Afrique de l’Ouest

M. OUEDRAOGO, J. E. PATUREL, G. MAHEInstitut de Recherche pour le Développement (IRD), 01 BP 182, Ouagadougou 01, Burkina Fasoe-mail: [email protected]

E. SERVAT, A. DEZETTERInstitut de Recherche pour le Développement (IRD), Hydrologie-Vahyne, BP 5045, F-34032 Montpellier Cedex, France

D. CONWAYClimatic Research Unit (CRU), University of East Anglia, Norwich NR4 7TJ, UK

Résumé Un important travail de récupération de données a été entrepris sur un domaine qui couvre principalement le Burkina Faso, la Côte d’Ivoire, et le Mali. Cette opération a abouti à la construction de trois grilles de données de pluie, de quatre grilles de données d’évapotranspiration potentielle (ETP). Les différents modèles à pas de temps mensuel utilisés faisant appel à une “donnée-sol”, que l’on peut définir comme proche d’une capacité de rétention en eau du sol, on a obtenu, également, deux grilles de valeurs. Appliqués à différents bassins versants couvrant des espaces géographiques bien distincts, les modèles ont donné des résultats qui varient en fonction des grilles de données utilisées, des bassins versants et des modèles eux-mêmes. Ces premiers résultats posent le problème de l’influence de la nature et de l’origine des données sur la modélisation hydrologique en Afrique.Mots clefs Afrique de l’Ouest; modélisation hydrologique; modélisation régionale; donnéesKey words West Africa; hydrological modelling; regional-scale modelling; data


A framework for coupling atmospheric and hydrological models

ALAIN PIETRONIRONational Water Research Institute, Environment Canada, Saskatoon, Saskatchewan S7N 3H5, Canada

e-mail: [email protected]

ERIC D. SOULIS, KEN SNELGROVE & NICK KOUWENDepartment of Civil Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

Abstract There is a strong global research effort in coupling atmospheric and hydrological models for improved hydrological flow modelling and improved atmospheric simulation. The land surface is an important hydrological control as it is the primary influence in the surface water budget and it is almost always a requirement in the implementation of either hydrological or atmospheric models. Sophisticated soil–vegetation atmospheric transfer (SVAT) schemes are currently being implemented in global climate models (GCMs), regional climate models (RCMs) and day-to-day operational forecasting numerical weather prediction models (NWPs). Rarely have these been incorporated into hydrological models. This paper focuses on describing the coupling of an atmospheric model (both NWP and RCM) with a hydrological model. A conceptual framework for model development was initiated using different levels of coupling in order to work towards a complete two-way coupled model.Key words numerical weather prediction model; hydrological model; land surface–atmosphere coupling; SVAT model; surface water budgets________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 299–305.

Snow vegetation interactions: issues for a new initiative

J. W. POMEROYCentre for Glaciology, Institute of Geography and Earth Sciences, University of Wales, Aberystwyth, SY23 3DB, UK e-mail: [email protected]

P. HÖLLERForstliche Bundesversuchsanstalt, Institut für Lawinenforschung, Hofburg–Rennweg 1, A-6020 Innsbruck, Austria

P. MARSHNational Water Research Institute, Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5, Canada

D. A.WALKERInstitute of Arctic Biology, University of Alaska Fairbanks, 311 Irving I, PO Box 757000, Fairbanks, Alaska 99775-7000, USA

M. WILLIAMSInstitute of Arctic and Alpine Research, CB 450, University of Colorado, Boulder, Colorado 80309-0450, USA

Abstract The Working Group on Snow–Vegetation Interactions of the IAHS International Commission on Snow and Ice has proposed enhanced study of the impact of stressors on snow–vegetation ecosystems such as deforestation, land-use change, climate change, long-range pollutants and land management and of the role of the snow–vegetation ecosystem in transmitting or moderating impacts from these stressors. These studies will include those that examine snow–vegetation interactive processes in various biomes, the relationship between these interactions and global atmospheric change, and the role of vegetation cover form, dynamics and management on snow and hydrology. Examples are shown here of case studies of snow–vegetation dynamics and implications for the environment, drawn from field studies in the Colorado Rocky Mountains, the Austrian Alps and the Canadian Sub-arctic. The examples are chosen to illustrate the utility of the principles outlined above when applied in the study of snow–vegetation ecosystems.Key words snow; vegetation; nutrients; terrestrial ecology; climate; hydrology; arctic; alpine; boreal forest; snow

drifts________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 333–341.

Estimating subsurface drainage from organic-covered hillslopes underlain by permafrost: toward a combined heat and mass flux model

W. L. QUINTON Department of Geography, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada e-mail: [email protected]

D. M. GRAYDivision of Hydrology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0W0, Canada

Abstract Estimation of subsurface flow from organic-covered, permafrost terrain requires information on the elevation and thickness of the saturated layer because the soil permeability decreases with depth. Since heat conduction governs the thawing of seasonal frost, temperature index models might provide reasonable estimates of the rate of ground thawing. The depth of thaw derived from an estimate of ground heat flux is shown to be in close agreement with the measured depth to the frost table. Surface temperature is recommended as the index of heat flux rather than air temperature because it is directly influenced by the energy exchanges occurring at the ground/air interface and within the active layer and its value can be estimated from remotely-sensed thermal infrared data. It is shown that the coefficient C of the relationship between friction factor, f and Reynolds Number, NR, (i.e. f = C/NR) increases linearly with the depth to the middle of the saturated zone, d. Since C = 2D2/K, where D is the geometric mean pore diameter of the material encountered by the saturated layer, and K is the soil permeability, the relationship between C and d allows an approximation of the variation in permeability with depth.Key words subsurface drainage; permafrost; soil thaw; coupled heat and mass flow


Contribution of satellite and lightning data to convective rainfall frequency analysis

MARIA HELENA RAMOSLTHE (CNRS-ORSTOM-UJF-INPG), BP 53, F-38041 Grenoble Cedex 9, Francee-mail: [email protected]

STEPHANE SENESICNRM/GMME, Météo-France, 42 Avenue G. Coriolis, F-31057 Toulouse Cedex 1, France

JEAN-DOMINIQUE CREUTINLTHE (CNRS-ORSTOM-UJF-INPG), BP 53, F-38041 Grenoble Cedex 9, France

CHRISTOPHE MORELCNRM/GMME, Météo-France, 42 Avenue G. Coriolis, F-31057 Toulouse Cedex 1, France

Abstract This paper aims to explore to what extent remotely sensed mesoscale convective

systems (MCSs) can be associated with ground rainfall. The two MCS identification methods used rely either on infrared satellite images alone or on both infrared images and lightning data. Rain data come from a network of 25 raingauges in Marseilles (France) from 1993 to 1997. The analysis of rainfall is developed conditionally on the occurrence of an MCS. The main results indicate differences in the rainfall distribution functions in terms of bulk features and maximal values. The mean and standard deviation of rainfall accumulations are multiplied by 2.5 when an MCS is identified compared to when no MCS is identified. The same happens for the slope of the distribution of the maximal values. A higher percentage of the total ground rainfall accumulation is detected when lightning data are also considered.Key words mesoscale convective system; lightning data; rainfall frequency analysis; satellite images


The phenology of four subalpine herbs in relation to snow cover characteristics

CHRISTIAN RIXEN, VERONIKA STOECKLI, CHRISTINE HUOVINEN & KAI HUOVINENSwiss Federal Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH-7260 Davos Dorf, Switzerlande-mail: [email protected]

Abstract To test vegetation development in relation to the snow cover characteristics of ski pistes, the soil temperature, time of snowmelt and phenology of flowering plants were recorded on plots with groomed artificial snow, groomed natural snow and untreated natural snow, on an experimental field near Davos, Switzerland. The soil temperature was lowest under the compressed artificial snow, and significantly lower under the compressed natural snow compared to the untreated natural snow. The snowmelt in April occurred first on the ungroomed natural snow, followed by the groomed natural snow and finally the groomed artificial snow. The phenology of the plants, postponed by the snow properties, followed the same pattern as the snowmelt until mid June. Although the difference in snow characteristics between the snow types was small, their impact on the early flowering plants was measurable for a relatively long time after the snowmelt.Key words artificial snow; phenology; ski pistes; snowmelt; soil temperature; vegetation


Toward improved parameter estimation of land surface hydrology models through the Model Parameter Estimation Experiment (MOPEX)

JOHN SCHAAKE, QINGYUN DUAN, VICTOR KOREN & ALAN HALLHydrology Laboratory/National Weather Service, 1325 East-West Highway, Silver Spring, Maryland 20910, USAe-mail: [email protected]

Abstract A key issue in land surface modelling is to estimate model parameters that vary spatially and are unique to each computational element. An international Model Parameter


Estimation Experiment (MOPEX) was established to develop techniques for the a priori estimation of the parameters used in land surface parameterization schemes of atmospheric models and in hydrological models. The major effort to achieve this goal is to assemble a large number of high quality historical hydrometeorological and river basin characteristics data sets for a wide range of intermediate-scale river basins (500–10 000 km2) throughout the world. Data sets from Phase I of MOPEX are available via the Internet. MOPEX Phase II activities will collect additional data from the USA as well as data for basins from other countries. During the next three years, the scientific community will use the available MOPEX data sets to estimate basin parameters and to relate them to basin characteristics. This paper presents the MOPEX science strategy, describes the MOPEX data sets, and illustrates the execution of MOPEX strategy with an example based on the Sacramento Soil Moisture Accounting model (SAC-SMA) used by US National Weather Service for river and flood forecasting.Key words hydrological models; parameter estimation; model calibration; parameter regionalization; MOPEX


Sub-grid runoff processes and hydrological modelling in the subarctic Canadian Shield

CHRISTOPHER SPENCEEnvironment Canada, Suite 301 5204 50th Avenue, Yellowknife, Northwest Territories X1A 1E2, Canadaemail: [email protected]

Abstract This paper discusses the application of a semi-distributed physically based hydrological model to the 16 000 km2 Yellowknife River basin. The model was calibrated, but attempts at validation failed. Errors in the vertical water budget and river routing portions of the model were not large enough to account for the differences between observed and modelled streamflow. Field studies suggest the model structure did not adequately simulate the effect of storage capacity differences between land cover types on the sub-grid transfer of runoff to the stream. Runoff is delayed or prevented from reaching higher order streams because of seasonal changes in hillslope and headwater lake storage capacities, while the model structure implies that any excess water from the hillslope vertical water budget is immediately transferred. Key words Canadian Shield; SLURP model; Yellowknife; runoff generation; hydrological modelling; water balance


Estimation model for litter moisture content ratio on forest floor

KOJI TAMAIKansai Regional Research Center, Forestry and Forest Products Research Institute, Momoyama-cho, Fushimi-ku, Kyoto 612-0855, Japane-mail: [email protected]

Abstract A model was developed to estimate litter moisture content for use in predicting the risk of forest fire in individual forest stands. A formula to calculate the rate of evaporation from litter was determined experimentally, using simulated litter moisture content and observed solar radiation. The model was applied to both a deciduous and a mixed deciduous-evergreen forest. The incidence of periods when the gravimetric moisture content was below 20% (R20) coincided with the incidence of real forest fires in the surrounding area. Values of R20 were higher in


deciduous than in mixed deciduous-evergreen forests because of the different sky view factors. These results suggest that estimates of litter moisture content can be used to assess the risk of fire in individual forest stands.Key words forest fire; tank model; sky view factor; solar radiation; deciduous forest________________________________________________________________________Soil–Vegetation–Atmosphere Transfer Schemes and Large-Scale Hydrological Models (Proceedings of a symposium held during the Sixth IAHS Scientific Assembly at Maastricht, The Netherlands, July 2001). IAHS Publ. no. 270, 2001, pp. 35–40.

Regional mechanistic estimations of sugar-cane water use

ANGEL UTSETAgrophysics Research Unit, Agricultural University of Havana (UNAH), Apdo 5117, La Habana 10500, Cubae-mail: [email protected]

GILBERTO LOPEZNational Center of Hydrology and Water Quality, Cuba

Abstract The application of a sugar-cane model, evolved from the mechanistic model SWAP, in the assessment of the sugar-cane water use and yields in Havana Province is shown. The model was interfaced to the GIS ILWIS in order to produce regional results. The soil hydraulic properties of all the sugar-cane cropping areas in the province were calculated through pedotransfer functions using available information from a 1:25 000 soil map. The daily values of the modified Penman evapotranspiration (ETP) were considered as the top boundary condition in the simulations. Free drainage was assumed as the bottom boundary condition of the 2-m layer. A weather generator was used to generate 50 years of daily rainfall and maximum ETP records. Site-specific assessments of water effects on sugar-cane yields were carried out, as well as water-management recommendations for each location. The present results can be used as a methodological guide for recommending the sugar-cane water management in any other part of the world.Key words mechanistic modelling; sugar-cane; crop water use; GIS; weather generator; Havana Province, Cuba


Directives for 4-D soil moisture data assimilation in hydrological modelling

E. E. van LOON & P. A. TROCHSub-department of Water Resources, Wageningen University, Nieuwe Kanaal 11, 6709 PA Wageningen, The Netherlandse-mail: [email protected]

Abstract Data assimilation is a procedure to provide time-dependent spatially-distributed estimates of a dynamic system using observations from various sources and with various physical constraints in an efficient way. Mathematically, it can be seen as a state estimation procedure. The spatio-temporal prediction of soil moisture is pre-eminently a problem that can be dealt with by data assimilation techniques. Even though there is considerable literature on data assimilation in the environmental sciences, the application to soil moisture estimation is still new. To date only the problem of integrating remotely sensed data or field-observations over a small area with a one-dimensional soil moisture model of the root zone has been studied. In all cases the assimilation technique comprises simplifications or variants of the weak-constraint variational


technique (equivalent to the Kalman smoother). Problems involving more spatial dimensions and more diverse information sources have not yet been dealt with. This is partly because the dimensionality of the problem prohibits a straightforward extension of the common algorithms, i.e. new data assimilation algorithms need to be developed. The lack of appropriate data sets and regularization tools is also a serious impediment. As a first step towards applying soil moisture data assimilation to problems of a higher dimension, this study outlines the desirable structure of 4-D hydrological data assimilation algorithms, and discusses the consequences for data handling and the specification of hydrological models.Key words 4-D data assimilation; soil moisture; review; Kalman filter; optimal estimation


Assimilation of soil moisture in a hydrological model for flood forecasting

A. WEISSE, C. MICHEL, D. AUBERT & C. LOUMAGNECemagref, BP 44, F-92163 Antony Cedex, France e-mail: [email protected]

Abstract This paper introduces a parameter updating procedure of the “variational” type that can be combined with any conceptual rainfall–runoff model for flood forecasting purposes. The main feature of this method is that it carries out updating by reference not only to recent streamflow observations, as do classic procedures, but also to soil moisture measurements, which can be retrieved either from TDR probes or from satellite remote sensing systems. The aim of the research was to assess the usefulness of this additional soil moisture information. The application of this new methodology has been carried out on a sub-basin of the River Seine at Paris. The first results are presented and, for this sub-basin, soil moisture seems not to be very useful to increase the efficiency of the updating procedure. But, due to the reduced number of recorded flood events, no definite conclusion can be reached.Key words assimilation; soil moisture; flood forecasting


Expanding distributed hydrological modelling to the continental scale

DAWEN YANGDepartment of Civil Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japane-mail: [email protected]

SHINJIRO KANAE, TAIKAN OKI & KATUMI MUSIAKEInstitute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-Ku, Tokyo 153-8505, Japan

Abstract Applying a grid-based distributed hydrological model to a continent cannot be achieved simply by increasing the grid size. This is due to the spatial heterogeneity and nonlinear nature of soil–vegetation–atmosphere transfer processes. Sub-grid hydrological parameterization is required to capture the spatial variability in a large grid. The methodology presented in this study expanded a grid-based distributed hydrological model to the continental scale, and addressed both

sub-grid hydrological parameterization based geomorphological property and the basin-based flow routing. The spatial information related to topography, land cover, and soil properties was estimated from the available finest resolution data sets. Application to the Asian continent has shown good simulations of river discharge in the main rivers, and the model could represent the general spatial hydrological characteristics. This continental-scale hydrological model can be coupled with GCMs for complete simulation of the continental water–energy cycle. Key words continental scale; hydrological model; GBHM model; sub-grid parameterization; runoff generation; flow routing


A completely-formed distributed rainfall–runoff model for the catchment scale

HUAXIA YAO & MICHIO HASHINOEnvironmental Hydrology, Department of Civil Engineering, The University of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506, Japan

Abstract A distributed model is proposed by integrating assimilation of input forcing onto grids, simulation of rainfall–evaporation–runoff processes at grids, computation of river routing, and calibration of spatial parameters. Spatial rainfall is assimilated with a spline interpolation, grid evapotranspiration and runoff are estimated with a soil–vegetation–atmosphere transfer scheme, river routing is calculated by a linear pool method, and parameters are calibrated by considering spatial heterogeneity. This daily runoff model is validated in the Hiji River catchment, Shikoku, Japan, resulting in good reproduction of daily discharges and annual water budgets. Key words distributed model; rainfall; spline interpolation; interception; Hiji River, Japan; spatial parameter; river routing; runoff


An analysis of the variation in hydrological conditions in the Korean peninsula due to global warming

YONG NAM YOONDepartment of Civil and Environmental Engineering, Korea University, Seoul 136-701, Koreae-mail: [email protected]

JAE SOO LEEDepartment of Civil and Environmental Engineering, Jeonju University, Jeonju 560-759, Korea

CHULSANG YOODepartment of Environmental Engineering, Korea University, Jochiwon 339-700, Korea

JAE HYUN AHNDepartment of Civil and Environmental Engineering, Korea University, Seoul 136-701, Korea

Abstract In this study, a mesoscale atmospheric/hydrological model (IRSHAM96) and a water

balance model are applied to predict the possible changes in hydrological conditions (precipitation, air temperature, runoff, etc.) in the Geum River basin, Korea. From the simulation results for 1´CO2 and 2´CO2 conditions, it was found that the precipitation, soil moisture and runoff would decrease in spring, winter and autumn, but increase in summer due to the increase in CO2. However, the air temperature and evapotranspiration amounts were found to increase in all seasons due to the increase in CO2. As a result, it was predicted that the frequency of drought and flood occurrences in the Geum River basin would increase due to global warming.Key words atmospheric/hydrological model (IRSHAM); CO2; water balance model; Geum River, Korea


Coupled regional-scale hydrological–atmospheric model for the study of climate impact on Japan

JUNICHI YOSHITANIIndependent Administrative Institution Public Works Research Institute, 1-6 Minamihara, Tsukuba, Ibaraki 305-8516, Japane-mail: [email protected]

M. L. KAVVAS & Z.-Q. CHENDepartment of Civil and Environmental Engineering, University of California at Davis, Davis, California 95616, USAe-mail: [email protected] and [email protected]

Abstract In order to be able to simulate long-term climate, it is necessary to model the evolution of both the atmospheric and hydrological variables in their fundamentally two-way interactive setting and to model the significant heterogeneity of land surface characteristics. A two-way feedback mode and the heterogeneity in a computational mesh are important keys to stable and realistic simulation. The coupling based on areally-averaged conservation equations was applied to a regional-scale atmospheric model for the main islands of Japan. Atmospheric–hydrological processes observed at Tsukuba station were compared with their counterparts simulated by the coupled model with a 20 ´ 20 km2 resolution for the January 1989 historical period. The results of this comparison are quite satisfactory. Then, the model of Japan was run to simulate the climate change over Japan under the scenario of the doubling of CO2 concentration in the atmosphere.Key words Integrated Regional Scale Hydrologic/Atmospheric Model (IRSHAM); areally-averaged Green-Ampt model; soil water flow model; climate change


Development of the evaporation component for the physically-based distributed tank model

ZONGXUE XUWater Resources Department, CTI Engineering Co. Ltd, Tokyo 103-8430, Japan

JINGYU LI Department of Land Management, Renmin University of China, Beijing 100872, China

KAZUMASA ITO Water Resources Department, CTI Engineering Co. Ltd, Tokyo 103-8430, Japan

Abstract In large river basins there may be considerable variation in both climate and land use across the region. The potential impact of these variations on the evapotranspiration is estimated for two study areas using a physically-based distributed model. Three kinds of models, the Penman-Kotoda, Morton and Brutsaert-Stricker models are validated. The ability of three models to estimate accurately the evaporation of basins with complex topography and land-use classifications is investigated by applying these models to two basins with different topographical and land-use features. Daily, monthly and annual variations for evaporation in the two basins are estimated. Comparison with the results obtained by the water balance method and others shows that the Penman-Kotoda model may underestimate the evaporation in some cases. The Morton and Brutsaert-Stricker models seem to be two kinds of available approaches for estimating the basinwide evaporation.Key words basins; evaporation; evapotranspiration; land-use classification; hydrological data; meteorological data

hydrologie.orghydrologie.org/redbooks/a270/p270 description, contents, … · web viewedited by...

Documents