watershed morphology & ecoregions

7/26/2019 Watershed Morphology & Ecoregions

1/14

PLEASE SCROLL DOWN FOR ARTICLE

This article was downloaded by: [Marston, Richard A.]

On: 14 December 2010

Access details: Access Details: [subscription number 931124572]

Publisher Routledge

Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-

41 Mortimer Street, London W1T 3JH, UK

The Professional Geographer

Publication details, including instructions for authors and subscription information:http://www.informaworld.com/smpp/title~content=t788352615

Watershed Morphology of Highland and Mountain Ecoregions in Eastern

Oklahoma

Dale K. Splintera; Daniel C. Dauwalterb; Richard A. Marstonc; William L. FisherbaUniversity of Wisconsin-Whitewater, bU.S. Geological Survey, Oklahoma Cooperative Fish andWildlife Research Unit, cKansas State University,

First published on: 13 December 2010

To cite this ArticleSplinter, Dale K. , Dauwalter, Daniel C. , Marston, Richard A. and Fisher, William L.(2010) 'WatershedMorphology of Highland and Mountain Ecoregions in Eastern Oklahoma', The Professional Geographer,, First publishedon: 13 December 2010 (iFirst)

To link to this Article DOI 10.1080/00330124.2010.533575

URL

http://dx.doi.org/10.1080/00330124.2010.533575

Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf

This article may be used for research, teaching and private study purposes. Any substantial orsystematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply ordistribution in any form to anyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae and drug dosesshould be independently verified with primary sources. The publisher shall not be liable for any loss,

actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directlyor indirectly in connection with or arising out of the use of this material.
http://www.informaworld.com/smpp/title~content=t788352615http://dx.doi.org/10.1080/00330124.2010.533575http://www.informaworld.com/terms-and-conditions-of-access.pdfhttp://www.informaworld.com/terms-and-conditions-of-access.pdfhttp://dx.doi.org/10.1080/00330124.2010.533575http://www.informaworld.com/smpp/title~content=t788352615


2/14

Watershed Morphology of Highland and MountainEcoregions in Eastern Oklahoma

Dale K. Splinter

University of WisconsinWhitewater

Daniel C. DauwalterU.S. Geological Survey, Oklahoma Cooperative Fish and Wildlife Research Unit

Richard A. MarstonKansas State University

William L. FisherU.S. Geological Survey, Oklahoma Cooperative Fish and Wildlife Research Unit

The fluvial system represents a nested hierarchy that reflects the relationship among different spatial andtemporal scales. Within the hierarchy, larger scale variables influence the characteristics of the next lowernested scale. Ecoregions represent one of the largest scales in the fluvial hierarchy and are defined by recurringpatterns of geology, climate, land use, soils, and potential natural vegetation. Watersheds, the next largestscale, are often nested into a single ecoregion and therefore have properties that are indicative of a givenecoregion. Differences in watershed morphology (relief, drainage density, circularity ratio, relief ratio, andruggedness number) were evaluated among three ecoregions in eastern Oklahoma: Ozark Highlands, BostonMountains, and Ouachita Mountains. These ecoregions were selected because of their high-quality stream re-sources and diverse aquatic communities and are of special management interest to the Oklahoma Departmentof Wildlife Conservation. One hundred thirty-four watersheds in first- through fourth-order streams werecompared. Using a nonparametric, two-factor analysis of variance ( = 0.05) we concluded that the relief,drainage density, relief ratio, and ruggedness number all changed among ecoregion and stream order, whereascircularity ratio only changed with stream order. Our study shows that ecoregions can be used as a broad-scaleframework for watershed management. Key Words: ecoregions, Oklahoma, streams, watershed morphology.

The Professional Geographer, 63(1) 2011, pages 113 C Copyright 2011 by Association of American Geographers.Initial submission, July2007; revised submissions, January and August 2008, May and September 2009; final acceptance,

November 2009.Published by Taylor & Francis Group, LLC.

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


3/14

2 Volume 63, Number 1, February 2011

El sistema fluvial representa una jerarqua anidada que refleja la relaci on entre diferentes escalas espacialesy temporales. Dentro de la jerarqua, las escalas variables mas grandes influyen sobre las caractersticas de lasiguiente escala anidada de menor valor. Las eco-regiones representan una de las escalas m as grandes en lajerarqua fluvial y se definen por medio de patrones recurrentes de geologa, clima, uso de la tierra, suelos yvegetaci on natural potencial. Las cuencas, que son la siguiente escala en importancia, a menudo se alberganen una sola eco-regi on y por tanto exhiben las propiedades indicativas de una eco-regi on dada. Las diferencias

en la morfologa de las cuencas (relieve, densidad de drenaje, raz on de circularidad, raz on de relieve y n umerode escabrosidad) fueron evaluadas entre tres eco-regiones del oriente de Oklahoma: los Altos de las Ozark,las Montanas de Boston, y las Montanas Ouachita. Se seleccionaron estas eco-regiones debido a su dotaci onde corrientes fluviales de alta caliudad y diversas comunidades acu aticas, y porque son de especial inter es demanejo para el Departamento de Conservaci on de Vida Silvestre de Oklahoma. Se compararon ciento treintay cuatro cuencas con corrientes del primero al cuarto orden. Utilizando un analisis de varianza de dos factores( = 0.05), no-parametrico, concluimos que el relieve, la densidad del drenaje, la raz on de relieve y el n umerode escabrosidad, en conjunto, cambiaron entre la eco-regi on y el orden de las corrientes, en tanto que la raz onde circularidad solo cambi o con el orden de las corrientes. Nuestro estudio muestra que las eco-regionespueden utilizarse como un marco de escala amplia para el manejo de cuencas.Palabras clave: eco-regiones,Oklahoma, corrientes, morfolog a de cuencas.

The fluvial system is spatially and tempo-rally hierarchical (Schumm and Lichty1965; Frissell et al. 1986; Kondolf et al. 2003).Schumm and Lichty (1965) explained that anintegrated set of independent and dependentvariables shape and control watershed char-acteristics over time and space. They arguedthat over a long duration (i.e., an erosionalperiod), time, initial relief, geology, and cli-mate are independent variables that influence

vegetation, sediment yield, hillslope morphol-ogy, and hydrology. In accordance with thework by Schumm and Lichty, Omernik (1987)stated that the causal factors of climate, soil andgeology, vegetation, and physiography defineecosystems in a regional framework. In turn,ecoregion delineations for the United Stateswere created by examining the factors thatcause regional variation or those factors thatintegrate causal factors (Omernik 1987). Kon-

dolf et al. (2003) stated that similarities in cli-mate, geomorphology, lithology, and land-usehistory will lead to stream channel characteris-tics that are inherently similar within a given re-gion. In a nested hierarchical order, the uniquecombination of geology, climate, vegetation,and land-use has and continues to influence wa-tershed morphology spatially and temporally.

Our objective was to determine whetherwatershed morphology differed among threeecoregions (Ozark Highlands, Boston Moun-tains, and Ouachita Mountains) in easternOklahoma. We hypothesize that watershedmorphology differs ( = 0.05) among ecore-gions because watershed evolution and thecurrent geomorphic processes acting in thewatershed result from the interplay of the re-sisting framework and driving forces applied to

geomorphic systems over time (Ritter, Kochel,and Miller 2002). Because the resisting frame-work (geologic structure and lithology) anddriving forces (climate and land use) differamong ecoregions, watershed evolution and thegeomorphic processes acting at multiple spatialscales are initiated at the ecoregion level. If ourhypothesis is accepted: (1) watershed morphol-ogy differs by ecoregion because the mosaicof natural and human forces that affect wa-

tershed morphology are more similar withinthan between ecoregions; and (2) watershedplanners and managers will be able to evalu-ate management options by ecoregion ratherthan on a watershed-by-watershed basis, whichwill permit more efficient use of resources andmore timely responses to needed managementchanges.

We studied 134 watersheds to examinewhether watershed morphology, measured as

relief, drainage density, circularity ratio, reliefratio, and ruggedness, differed among threephysically contrasting ecoregions in easternOklahoma. The morphological metrics pre-viously listed were used because they are of-ten used to describe watershed morphology(Patton and Baker 1976; Harlin 1984; Liebaultet al. 2002).

Ecoregions and Watershed

ManagementEcoregions were originally developed to pro-vide a geographic framework for ecosystemmanagement (Omernik 1987). Omernik (1987)stated that ecoregions will allow managers,planners, and scientists to (1) compare similari-ties and differences of landwater relationships;

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


4/14

Watershed Morphology of Ecoregions in Eastern Oklahoma 3

(2) establish water quality standards that are ac-ceptable for a given region; (3) locate places toserve as monitoring, demonstration, and refer-ence sites; (4) extrapolate from empirical datacollected at other locations; and (5) predict the

effect of land-use change. Omernik and Bailey(1997) reiterated the importance of ecoregionsin providing a spatial framework for ecosys-tem assessment, research, inventory, monitor-ing, and management. Extrapolation of site-specific data across an ecoregion allows for theprediction of system function at unsampled lo-cations (Omernik and Bailey 1997).

Hundreds of millions of dollars are investedannually to manage and restore watersheds inNorth America (Roni 2005). Comprehension

of how landscape controls (i.e., geology, cli-mate, land use, soils, and vegetation) influencewatershed processes is important for the suc-cessful management and restoration of water-sheds. Watershed processes influence streamhabitat, which is critical for ecosystem func-tion at smaller scales (Roni 2005). Ecoregionsencompass the broad-scale landscape controlsthat watershed managers need to understandbefore management plans can be developed and

initiated. Failure to understand linkages be-tween scales in the fluvial hierarchy can resultin unsuccessful watershed management plans(Frissell and Ralph 1998).

Loveland and Merchant (2004, S1) wrotethat ecoregions fuse the concept of ecosystemswith the geographic concept of regions. Indoing so, they underscored the importanceamong ecology, geography, and geomorphol-ogy. Studies involving fish, macroinvertebrates,

and geomorphology have utilized ecoregionsas a spatial framework for study (Larsenet al. 1986; Rohm, Giese, and Bennett 1987;Lyons 1989; Newell and Magnuson 1999;McCormick, Peck, and Larsen 2000; Panet al. 2000; Rabeni and Doisy 2000; Dauwalteret al. 2007; Dauwalter et al. 2008). Thedynamic relationship bridging ecology andgeomorphology was portrayed at the 36thInternational Geomorphology BinghamtonSymposium in 2005 and the 2004 Associationof American Geographers annual meeting inPhiladelphia, Pennsylvania (Renschler, Doyle,and Thoms et al. 2007; Urban and Daniels2006). Aquatic scientists recognize that habitatdictates the richness and abundance of species,which is partly influenced by the characteristicsof the ecoregion (Dauwalter et al. 2008).

Watershed Morphology

Geomorphologists use morphometric analysisto investigate watershed morphology quantita-tively (Chorley, Schumm, and Sugden 1984).Horton (1932) introduced watershed analysisto explain watershed function (Gregory andWalling 1973). This quantitative morphome-tric analysis of watersheds was continued by aseries of methodological and theoretical papersspanning more than a quarter century (Horton1945; Langbein 1947; Strahler 1952, 1958,1964; Schumm 1956). These papers helpedestablish how morphometric analyses couldbe used to differentiate geomorphologicalprocesses in contrasting regions.

Morisawa (1962) investigated whether thewatersheds of the Allegheny Plateau, AlleghenyMountains, and Cumberland Plateau regions ofthe Appalachian Plateau were morphologicallydifferent. She found that watershed morphol-ogy differed among these regions. Morisawastated that these findings support separatingeach of the three regions into distinct geo-morphic sections. Lewis (1969) used similarwatershed characteristics to classify Indiana

into contrasting morphometric regions.Morphometric analyses have recentlybeen used in process-based studies and forenvironmental management. Jamieson et al.(2004) showed that tectonic zones in theIndus Valley of Ladakh, in north India, can bedifferentiated using morphometric analyses oflongitudinal valleys. Watersheds draining oneof the tectonic zones were shorter, narrower,and had lower hypsometric integrals thanthe other two. These watersheds have beeninfluenced by thrust propagation that has led toerosion and increased sediment delivery to themain stem of the river and elevated local baselevels. Morphometric analyses have also beenconducted on paleodrainages in the desertsof Kuwait to understand the genesis and hy-drological implications of runoff (Al-Sulaimi,Khalaf, and Mukhopadhyay 1997).

Watershed morphology influences the re-sponse of a flood hydrograph for a given basin.

The shape of the flood hydrograph is dictatedby the routing of water through the watershed(Ritter, Kochel, and Miller 2002). Patton andBaker (1976) reported that drainage densityand stream frequency are good measuresto predict peak discharge for watersheds inregions with unlike characteristics. Drainage

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


5/14


density is an areal morphometric variable thatis often a function of climate, lithology, andrelief (Chorley, Schumm, and Sugden 1984).Semiarid watersheds generally have higherdrainage densities than humid watersheds

because less precipitation decreases vegetation,which accelerates overland flow and erosionin arid regions (Ritter, Kochel, and Miller2002). In regions with similar climate andprecipitation regimes, lithology and relief (re-sisting framework) are the dominant controlson drainage density (Chorley, Schumm, andSugden 1984). Watershed circularity also playsa prominent role in the characteristics of theflood hydrograph. Assuming that watershedshave similar patterns of stream networks, cir-

cular watersheds will supply flow to the outletmore quickly than elongated watersheds (Singh1992). This is particularly true in watershedswith high relief ratios and ruggedness numbers.

Watershed morphology also affects aquaticorganisms. Potter et al. (2004) found thataquatic biodiversity in North Carolina ismost at risk in agricultural lands drainingwatersheds with high circularity becausecircular watersheds have short delivery times

of maximum flow. This decreases the amountof time available for pollutants to settle out ofthe water, which increases water quality degra-dation and decreases biodiversity of aquaticmacroinvertebrates. Relationships amongmorphometric variables, stream habitat, andfish abundance have been documented in smallRocky Mountain streams (Lanka, Hubert, andWesche 1987). Lanka, Hubert, and Wesche(1987) found that low basin relief, low relief

ratio, and relatively low drainage density pro-duced the better trout habitat and concludedthat measures of drainage basin morphologycould be useful for predicting trout habitat instreams via simple morphometric calculations.

Study Area

We investigated to what extent the resistingframework and driving forces acting withinecoregions (Ozark Highlands, Boston Moun-tains, and Ouachita Mountains) had an effecton watersheds in eastern Oklahoma (Figure 1).These ecoregions have high-quality stream re-sources that support diverse aquatic commu-nities (Dauwalter et al. 2008). Black bass (Mi-cropterusspp.) are popular sport fishes in thesestreams, and recreational fishing provides im-

portant economic revenue in this portion ofOklahoma (Fisher et al. 2002). As a result,the Stream Management Program of the Ok-lahoma Department of Wildlife Conservationis active in managing stream resources in east-

ern Oklahoma (Hyler et al. 2004). Black basspopulations have been shown to differ amongecoregions in eastern Oklahoma (Balken-bush and Fisher 2001; Dauwalter and Fisher2008), and fisheries management has beenregionalized to reflect these differences (Fisher,Tejan, and Balkenbush 2004). Although pop-ulations are known to differ, stream habitatmanagement is based on the physical charac-teristics of stream channels nested within thehierarchy of the fluvial system. Addressing how

variables making up ecoregions influence wa-tershed morphology is a critical step in deter-mining whether resource management focusedon the physical aspects of the fluvial system canalso be regionalized.

Woods et al. (2005) described the OzarkHighlands as being composed of watershedsthat are high to moderately dissected. Lithol-ogy is mostly limestone and dolostone withinterbedded chert. Karst features, such as sink-

holes and caves, are common. Cool, spring-fedperennial streams are also common; however,during the summer many first- and second-order streams are dry and third- and fourth-order streams become intermittent (Splinter2006). Precipitation is approximately 100 cmto 125 cm annually. Prior to the nineteenthcentury, the plateau region consisted of oak-hickory forests and grasslands; today, agricul-tural land and increased residential areas have

replaced native vegetation (Woods et al. 2005).Rapid suburbanization of the region, alongwith intensive grazing and poultry farms, hasgreatly decreased water quality in some streams(Peterson et al. 1998; Woods et al. 2005). Soilorders on uplands consist of Ultisols, Alfisols,and Mollisols.

The Boston Mountains are immediatelysouth and west of the Ozark Highlands. Likethe Ozark Highlands, this region is highlydissected (Woods et al. 2005). A difference inlithology between the Boston Mountains andOzark Highlands is the main characteristic thatdistinguishes these two regions. Lithology ofthe Boston Mountains is primarily sandstoneand shale, with minor amounts of limestone.Streams in this region tend to be cool waterbut less influenced by springs than streams

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


6/14


Figure 1 Randomly selected pour points on streams (stream orders 14) in the Ozark Highlands, Boston

Mountains, and Ouachita Mountains ecoregions in eastern Oklahoma. Contributing watersheds above

each pour point were delineated and used in morphometric analyses.

in the Ozark Highlands (Woods et al. 2005).Channel substrate tends to be larger than thecherty gravel existing in streams of the OzarkHighlands (Splinter 2006). Precipitation is

approximately 110 cm to 130 cm annually.Land use consists of forest and woodland, withflatter areas used for ranching and farming.The potential natural vegetation includes

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


7/14


mostly oak-hickory forest (Woods et al. 2005).Soil orders on uplands consist of Ultisols,Inceptisols, and Entisols.

The Ouachita Mountains are south of theBoston Mountains. The Ouachita Mountains

ecoregion is a mosaic of low mountains andhigh hills (150750 m of local relief) of foldedPaleozoic rocks (Woods et al. 2005). Lithology,highly variable across the ecoregion, consistsmostly of sandstone, shale, and novaculite.Streams in this region are often confinedby geologic structure and large substrates,lack springs, and have a reduced summerflow (Splinter 2006). Maximum mean annualprecipitation occurs on south-facing ridges,increases to the east, and is 110 cm to 145 cm

annually. Much of the Ouachita Mountainsare forested, with larger valleys used for pas-tureland (Woods et al. 2005). Specific land useincludes forestry, logging, ranching, woodlandgrazing, and recreation. Commercial pineplantations are scattered across the ecoregion(Woods et al. 2005). The potential naturalvegetation includes oak-hickory-pine forest(Woods et al. 2005). Soil orders consist ofUltisols, Alfisols, and Inceptisols.

Method

Watershed Selection

We randomly selected watersheds in the OzarkHighlands, Boston Mountains, and OuachitaMountains ecoregions (Figure 1). To select wa-tersheds, we randomly selected 149 pour pointson a stream network and delineated the water-

sheds for each pour point. The stream networkwas delineated in ArcView 3.3c using a 30-m

Digital Elevation Model from the USGS Na-tional Elevation Dataset. We used a flow accu-mulation threshold of 1.35 km2 that matchedthe extent of the stream network from 1:24,000topographic maps and accurately depicted first-

order stream initiation. The number of water-sheds selected per ecoregion was approximatelyproportional to the area of each ecoregion:twenty-five in the Ozark Highlands, thirty-one in the Boston Mountains, and seventy-eight in the Ouachita Mountains. Watershedswithin each ecoregion were equally distributedamong stream orders one through four. This al-lowed for comparable sampling coverage acrossall three ecoregions and ensured that water-sheds of both small and large streams were

sampled. Watersheds that were not at least 90percent within one ecoregion were excluded.Only a limited number of different fourth-order streams could be selected in the OzarkHighlands and Boston Mountains because ofecoregion size. Of the 149 watersheds origi-nally selected, only 15 (10.1 percent) failed tomeet the 90 percent confinement criteria andthe remaining 134 were used for the analysis.

Morphometric Variables

Five morphometric variables were measuredusing ArcView 3.3c and ArcGIS 9.1c (ESRI,Redlands, CA; Table 1). Drainage density wascalculated by dividing the sum of stream lengthsin the watershed by the watershed area (Horton1945). Circularity ratio is the area of thewatershed divided by the area of a circle withthe same perimeter as the basin (Miller 1953).

This variable expresses the overall shape ofthe watersheds. A value of one represents a

Table 1 Watershed variables used to discriminate morphology difference among ecoregions

Variable Source Calculation Purpose

Drainage density(km/km2)

Horton (1945) stream length/Watershed area Expresses the overalldissection of the watershed

Circularity ratio Miller (1953) Area of watershed/Area of circle Represents how quickly waterenters and exits the stream

Relief (m) Strahler (1952),Schumm (1956)

High elevation Low elevation Influences the erosion potentialof the watershed

Relief ratio Schumm (1956) Watershed relief/Watershedlength

Represents the overallsteepness of the watershed

Ruggedness number Patton and Baker(1976)

Drainage density Basin relief Used to measure the flashflood potential of streams

Note:Table modified after Strahler (1958).

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


8/14


perfect circle. Relief is the highest elevationin the watershed minus the lowest elevation inthe watershed. Relief ratio was calculated bydividing the total basin relief (outlet to sum-mit of watershed) by the basin length (Schumm

1956). The basin length used to calculate the re-lief ratio was a straight line from the watershedoutlet to the summit, unless the straight linewould have crossed the watershed boundary.Where this occurred, the line was bent alongthe channel and continued until the watershedand the valley were parallel. Ruggedness num-ber is basin relief multiplied by drainage den-sity.

Statistical AnalysisAlthough our primary interest was in how wa-tershed morphology varied among ecoregionsand stream orders, we used Spearman rank cor-relations to show the interrelationships amongwatershed morphology variables. Differencesin watershed morphology among ecoregionsand stream orders were determined using anonparametric, two-factor analysis of variancewith watershed morphology as the response

variable, and the ecoregion and stream orderas the main effects. Analyses were done onranked data because variances were differentamong stream orders for some variables. Lin-ear contrasts were used to determine pairwisedifferences in watershed morphology amongecoregions when an ecoregion main effect wasevident (Kuehl 2000). Polynomial contrastswere used to test for trends in watershed mor-phology with stream order (Kuehl 2000). Type

I error rate was set at = 0.05. Analyses weredone using SAS version 9.1 statistical software(SAS Institute, Inc., Cary, NC). Rejection ofthe statistical null hypothesis (H0) would sup-port our scientific hypothesis (H1):

H0: Watershed morphology is not different( 0.05) among ecoregions.

H1: Watershed morphology is different ( 0.05) among ecoregions.

If H1 is accepted, the resisting framework(lithology and structure) and driving forces(land use and climate) that influence watershedmorphology can be differentiated by ecoregion.For example, changes to driving forces (i.e.,land use) impact ecological and geomorphicprocesses occurring at the watershed scale.

Results and Discussion

Watershed morphology differed among ecore-gions in eastern Oklahoma (Table 2), andmorphologic variables within ecoregions werehighly correlated (Table 3). Although the highcorrelations were not surprising given thatsome watershed morphology variables wereused to calculate others, the differences in wa-tershed morphology among ecoregions whilesimultaneously accounting for stream orderssupports our hypothesis that ecoregions repre-sent broad-scale composite variables that con-trol the development of the fluvial hierarchy.As a result, ecoregions can provide a frameworkto regionalize watershed management and themanagement of stream resources.

Table 2 Summary data for watershed morphology: Means and standard deviation (in parentheses) foreach of the variables by stream orders are reported

Drainagedensity Circularity Relief Relief Ruggedness

Region and order Number (km/km2) ratio (m) ratio number

Boston Mountains (1) 6 0.33 (0.27) 0.64 (0.05) 118.81 (71.48) 0.06 (0.03) 0.05 (0.05)Ozark Highlands (1) 7 0.42 (0.25) 0.60 (0.11) 58.77 (23.36) 0.02 (0.01) 0.03 (0.02)Ouachita Mountains (1) 19 0.50 (0.26) 0.55 (0.14) 157.06 (78.14) 0.06 (0.04) 0.07 (0.05)Boston Mountains (2) 9 0.49 (0.06) 0.53 (0.06) 175.94 (49.80) 0.04 (0.02) 0.09 (0.03)Ozark Highlands (2) 6 0.70 (0.16) 0.45 (0.10) 79.64 (20.26) 0.02 (0.01) 0.06 (0.02)Ouachita Mountains (2) 22 0.64 (0.13) 0.48 (0.11) 223.50 (136.29) 0.03 (0.01) 0.15 (0.11)Boston Mountains (3) 9 0.63 (0.04) 0.41 (0.09) 256.10 (41.52) 0.02 (0.01) 0.16 (0.03)Ozark Highlands (3) 7 0.68 (0.08) 0.42 (0.11) 134.29 (41.24) 0.01 (0.01) 0.09 (0.02)Ouachita Mountains (3) 19 0.71 (0.11) 0.40 (0.10) 320.20 (124.83) 0.02 (0.01) 0.22 (0.09)Boston Mountains (4) 7 0.65 (0.02) 0.32 (0.05) 379.88 (76.37) 0.01 (0.00) 0.25 (0.05)Ozark Highlands (4) 5 0.71 (0.04) 0.40 (0.05) 152.80 (10.77) 0.01 (0.00) 0.11 (0.01)Ouachita Mountains (4) 18 0.72 (0.06) 0.41 (0.06) 379.41 (181.26) 0.01 (0.01) 0.27 (0.11)

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


9/14


Table 3 Spearman rank correlations (rs)between watershed morphology variables and stream orderby ecoregion

Drainage density (km/km2) Circularity ratio Relief (m) Relief ratio

Boston Mountains (n = 31)Circularity ratio 0.590

Relief (m) 0.694 0.791Relief ratio 0.601 0.853 0.703Ruggedness 0.784 0.806 0.974 0.762

Ozark Highlands (n = 26)Circularity ratio 0.707Relief (m) 0.411 0.690Relief ratio 0.456 0.558 0.456Ruggedness 0.601 0.579 0.942 0.581

Ouachita Mountains (n = 78)Circularity ratio 0.561Relief (m) 0.247 0.372Relief ratio 0.563 0.600 0.013

Ruggedness 0.529 0.549 0.663 0.243

All correlations are significant ( p< 0.05) except those with an asterisk ().

Relief

Relief differed among ecoregions, F(2, 128) =34.12, p < 0.001, and stream order, F(3, 128)= 30.75, p < 0.001. Relief was lower inthe Ozark Highlands than in the OuachitaMountains, F(128) = 66.36, p = 0.001, andBoston Mountains,F(128)= 39.96,p = 0.001.

No difference in relief existed between theOuachita Mountains and Boston Mountains,F(128) = 0.65, p = 0.420. Polynomial con-trasts showed that relief increased with streamorder in all ecoregions, F(128) = 88.20,p < 0.001.

Watershed relief in the Ozark Highlands waslower in all stream orders than the relief in theOuachita Mountains and the Boston Moun-tains (Figure 2). The Ozark Highlands are

more closely associated with plateau-like char-acteristics (i.e., Springfield Plateau) than themore rugged Ouachita Mountains and BostonMountains. The watersheds of the OzarkHighlands, however, tend to be moderately tohighly dissected, with well-established streamnetworks. Maximum elevations in the OzarkHighlands are approximately 450 m, and min-imum elevations are less than 120 m in the val-ley bottoms (Woods et al. 2005). The BostonMountains consist of low mountains and rolling

hills with higher maximum and minimum ele-vations than the Ozark Highlands. Maximumelevations are approximately 520 m, with min-imum elevations of approximately 140 m. TheOuachita Mountains have both the highest andlowest elevations among the three ecoregions.

This region of folded mountains and open hillshas maximum elevations that exceed 800 m, andvalley elevations are less than 20 m (Woodset al. 2005). The northern boundary of theOuachita Mountains consists of east to westtrending watersheds that have the highest reliefin the region.

Drainage Density

Drainage density differed among ecoregions,F(2, 128)= 11.88,p


10/14


Figure 2 Watershed characteristics by ecoregion and stream order. Mean values are shown, and error

bars are 1 SE. Ecoregions with different letters were significantly different ( = 0.05) as determined

by linear contrasts.

between watershed relief and drainage densityholds true when examining the OuachitaMountains. The Ozark Highlands, however,have a higher drainage density with a much

lower relief than either the Ouachita Moun-tains or the Boston Mountains (Figure 2).Watersheds in the Boston Mountains havethe lowest drainage density but the secondhighest relief. These results suggest thatanother variable or combination of variables is

responsible for controlling drainage density inthe Ozark Highlands.

Previous studies have found that lithology,a resisting framework variable, plays a signif-

icant role in the drainage density of streams(Ray and Fisher 1960; Hadely and Schumm1961; Liebault et al. 2002). The lithology ofthe Ozark Highlands is comprised primarilyof chert and limestone (e.g., cherty limestone)that weathers and erodes more easily than the

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


11/14


sandstones in the Boston Mountains and sand-stones and novaculites of the Ouachita Moun-tains. The Ozark Highlands consist of well toexcessively drained soils that form in colluviumand the underling clay residuum from cherty

limestone. During high-intensity rainfall, in-filtration is low and sheet erosion is common.Where surface limestone has been dissolved,the headward migration of a stream channelhas been intensified. The jointed and fracturedlimestone (i.e., lithology and structure) servesas a catalyst for rill development and the head-ward migration that initiates stream channels.It is possible that the highly dissolvable chertylimestone of the Ozark Highlands has pro-moted the initiation of stream channels and in-

fluenced drainage densities in these watersheds.In addition to lithology and underly-

ing geologic structure, land use (i.e., drivingframework) might have played a role in the highdrainage density of the Ozark Highlands. Stud-ies of the Ozark Highlands in Missouri reportthat changes in land use between the mid-1800sand mid-1900s influenced the headward mi-gration of streams and indirectly increased thedrainage density of these watersheds (Jacobson

and Primm 1997). Missouri Ozark streams arelike those in the Oklahoma Ozarks; streams inboth regions contain large amounts of gravelthat is being redistributed throughout thesystem during mid- to high-magnitude floods(Jacobson 1995; Remshardt and Fisher 2009).Jacobson and Primm (1997) proposed that theincrease in gravel resulted from the extensionof the stream network. If gravel is comingfrom the headward migration of channels, then

the erosion from land use change probablyplays a role in the higher drainage density ofthe Oklahoma Ozark Highlands, which wereextensively logged in the late 1800s and themid-1900s (Rice and Penfound 1959) and laterbecame open-range grazing land.

Changes in land use have also occurredin the Boston Mountains and the OuachitaMountains. The drainage densities in theseregions apparently have been impacted lessby changes in land use than in the OzarkHighlands. These differences might be at-tributed to the more resistant lithology andstructure of the Boston Mountains and theOuachita Mountains. Ridgetops of the BostonMountains are primarily resistant sandstonewith sideslopes of interbedded sandstone and

shale (Woods et al. 2005). The OuachitaMountains consist of sandstone, shale, chert,and novaculite. Hillslopes are more resistant toerosion in the Boston Mountains and OuachitaMountains and are impacted less by changes in

land use than those in the Ozark Highlands.

Circularity Ratio

Circularity ratio changed with stream order,F(2, 128) = 24.79, p < 0.001, but did not dif-fer among ecoregions, F(2, 128) = 0.33, p =0.718). Circularity decreased with stream orderin all ecoregions, F(128) = 70.07, p 0.001(Figure 2). These results show that basin shapedoes not differ among the three ecoregions.

Relief Ratio

Relief ratio differed among ecoregions, F(2,128)= 18.17,p


12/14


ruggedness number increases with stream orderin all ecoregions, F(128) = 146.42, p < 0.001.Ruggedness number increased as watershedsize increased (Figure 2). This occurs becausedrainage density and relief increase as water-

shed size increases, both of which are multipliedtogether to calculate ruggedness number.

Conclusion

We demonstrated that four of five commonmorphometric variables used to describe water-shed morphology differed among ecoregionsand all five variables differed by stream order.This supports the premise that variables mak-ing up ecoregions influenced watershed mor-

phology, which should cascade to lower levelsof the fluvial system and result in channel mor-phology differences among ecoregions. Furtherstudies are needed to quantify how the resist-ing framework and driving forces of the water-shed impact stream channel processes and alsoto determine which of the watershed morphol-ogy variables we studied truly influence streammorphology because of the high degree of in-terrelatedness among them. Regardless, ecore-

gions provide a framework for watershed andstream management that is based on the hier-archical nature of the fluvial system.

The regional differences portrayed in this ar-ticle are important to agencies, such as the Ok-lahoma Department of Wildlife Conservation,that manage stream habitats and aquatic or-ganisms based on the morphology of the fluvialsystem. Because fluvial systems differ amongecoregions, regionalization of watersheds and

stream management by ecoregion should bebeneficial to managers with limited resources.Watershed management strategies (i.e., sus-pended sediment concentration, stream chan-nel restoration, aquatic habitat surveys, waterquality parameters, etc.) can be developed andimplemented by ecoregion.

Ecoregions provide a direct linkage betweenthe spatial framework necessary to understandaquatic ecosystem form and function andmultispatial scales. We showed that ecoregionsare useful for the regionalization of watershedmorphology and that, in turn, the nested fluvialhierarchy can begin by ecoregion. Additionalstudies are needed to evaluate how watershedmorphology can be used to help predict streammorphology. The response of land use change

on Ozark Highland streams needs to be betterunderstood. In addition, Level IV ecoregionshave been established for much of the UnitedStates. Level IV ecoregions are more de-tailed, which might allow for more detailed

assessment of watershed morphology and theassociated cascading fluvial hierarchy.

Literature Cited

Al-Sulaimi, J., F. J. Khalaf, and A. Mukhopadhyay.1997. Geomorphological analysis of paleo drainagesystems and their environmental implications inthe deserts of Kuwait. Environmental Geology 29:94111.

Balkenbush, P. E., and W. L. Fisher. 2001. Pop-

ulation characteristics and management of blackbass in eastern Oklahoma streams.Proceedings of theSoutheastern Association of Fish and Wildlife Agencies53:13043.

Chorley, R. J., S. A. Schumm, and D. E. Sugden.1984.Geomorphology.London: Methuen.

Dauwalter, D. C., and W. L. Fisher. 2008. Spa-tial and temporal patterns in stream habitat andsmallmouth bass populations in eastern Oklahoma.Transactions of the American Fisheries Society 137:107288.

Dauwalter, D. C., D. K. Splinter, W. L. Fisher,and R. A. Marston. 2007. Geomorphology andstream habitat relationships with smallmouthbass (Micropterus dolomieu) abundance at multi-ple spatial scales in eastern Oklahoma. Cana-dian Journal of Fisheries and Aquatic Sciences 64:111629.

. 2008. Biogeography, ecoregions, and ge-omorphology affect fish species composition instreams of eastern Oklahoma, USA.EnvironmentalBiology of Fish82:23749.

Fisher, W. L., D. F. Schreiner, C. D. Martin, Y. A.Negash, and E. Kessler. 2002. Recreational fishingand socioeconomic characteristics of eastern Ok-lahoma stream anglers.Proceeding of the OklahomaAcademy of Science82:7987.

Fisher, W. L., E. C. Tejan, and P. E. Balkenbush.2004. Regionalization of stream fisheries manage-ment using geographic information systems. InGIS/spatial analysis in fishery and aquatic sciences, ed.T. P. Nishida, J. Kailola, and C. E. Hollingworth,46576. Saitama, Japan: FisheryAquatic GIS Re-search Group.

Frissell, C. A., W. J. Liss, C. E. Warren, and M. D.Hurley. 1986. A hierarchical framework for streamhabitat classification: Viewing streams in a water-shed context. Environmental Management10:199214.

Frissell, C. A., and S. C. Ralph. 1998. Streamand watershed restoration. In River ecology and

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


13/14


management: Lessons from the Pacific coastal ecoregion,ed. R. J. Naiman and R. E. Bilby, 599624. NewYork: Springer.

Gregory, K. J., and D. E. Walling. 1973. Drainagebasin form and process: A geomorphological approach.New York: Wiley.

Hadely, R. F., and S. A. Schumm. 1961. Sedimentsources and drainage-basin characteristics in theupper Cheyenne River basin.US Geological SurveyWater Supply Paper1531-B:13796.

Harlin, J. M. 1984. Watershed morphometry andtime to hydrograph peak.Journal of Hydrology 67:14154.

Horton, R. E. 1932. Drainage basin characteristics.Transactions of the American Geophysical Union 13:35061.

.1945. Erosional developments of streams and

their drainage basin: Hydrophysical approach toquantitative morphology. Bulletin of the GeologicalSociety of America56:275370.

Hyler, R. G., P. E. Balkenbush, J. R. Vincent, andM. A. Dunham. 2004. Design and installation oftwo streambank stabilization projects in north-east Oklahoma. In Warmwater streams symposiumII, ed. J. R. Copeland, F. C. Fiss, P. E. Balken-bush, and C. S. Thomason, 4548. Oklahoma City,OK: Warmwater Streams Technical Committee,Southern Division, American Fisheries Society.http://www.sdafs.org/wwstreams/wwsc1.htm (last

accessed 16 November 2010).Jacobson, R. B. 1995. Spatial controls on patterns

of land-use induced stream disturbance at thedrainage basin scaleAn example from gravel-bedstreams of the Ozark Plateaus, Missouri. InNaturaland anthropogenic influences in fluvial geomorphology:The Wolman volume, ed. J. E. Costa, A. J. Miller,K. W. Potter, and P. R. Wilcock, 219239. Wash-ington, DC: American Geophysical Union.

Jacobson, R. B., and A. T. Primm. 1997. Histor-ical land-use changes and potential effects on

stream disturbance in the Ozark Plateau, Missouri.United States Geological Survey Water-SupplyPaper 2484, Denver, CO.

Jamieson, S. S. R., H. D. Sinclair, L. A. Kirstein, andR. S. Purves. 2004. Tectonic forcing of longitudi-nal valleys in the Himalaya: Morphological analysisof the Ladakh Batholith, North India.Geomorphol-ogy58:4965.

Kondolf, G. M., D. R., Montgomery, H. Piegay,and L. Schmitt. 2003. Geomorphic classificationof rivers and streams. InTools in fluvial geomorphol-ogy, ed. G. M. Kondolf and H. Piegay, 171204.Chichester, UK: Wiley.

Kuehl, R. O. 2000. Design of experiments: Statisti-cal principles of research design and analysis. PacificGrove, CA: Brooks/Cole.

Langbein, W. B. 1947. Topographic characteristicsof drainage basins. U.S. Geological Survey, WaterSupply Paper968-C:125157.

Lanka, R. P., W. A. Hubert, and T. A. Wesche.1987. Relations of geomorphology to stream habi-tat and trout standing stock in small Rocky Moun-tain streams. Transactions of the American FisheriesSociety116:2128.

Larsen, D. P., J. M. Omernik, R. M. Hughes, C. M.

Rohm, T. R. Whittier, A. J. Kinney, A. L. Gal-lant, and D. R. Dudley. 1986. Correspondencebetween spatial patterns in fish assemblages inOhio streams and aquatic ecoregions.Environmen-tal Management10:81528.

Lewis, L. A. 1969. Analysis of surficial landformpropertiesThe regionalization of Indiana intomorphometric similarity.Proceedings of the IndianaAcademy of Science78:31728.

Liebault, F., P. Clement, H. Piegay, C. F. Rogers,G. M. Kondolf, and N. Landon. 2002. Contempo-

rary channel changes in the Eygues basin, southernFrench Prealps: The relationship of subbasin vari-ability to watershed characteristics. Geomorphology45:5366.

Loveland, T. R., and J. M. Merchant. 2004. Ecore-gions and ecoregionalization: Geographical andecological perspectives. Environmental Manage-ment34:S1S13.

Lyons, J. 1989. Correspondence between the distri-bution of fish assemblages in Wisconsin streamsand Omerniks ecoregions.American Midland Nat-uralist122:16382.

McCormick, F. H., D. V. Peck, and D. P. Larsen.2000. Comparison of geographic classificationschemes for Mid-Atlantic stream fish assemblages.Journal of the North American Benthological Society19:385404.

Miller, V. C. 1953. A quantitative geomorphic studyof drainage basin characteristics in the ClinchMountain area, Virginia and Tennessee. TechnicalReport No. 3, Department of Geology, ColumbiaUniversity, New York.

Montgomery, D., and W. E. Dietrich. 1989. Chan-

nel initiation, drainage density, and slope. WaterResources Research25:190718.

Morisawa, M. 1962. Quantitative geomorphologyof some watersheds in the Appalachian Plateau.Bulletin of the Geological Society of America 73:102546.

Mosley, M. P. 1974. Experimental study of rill ero-sion.Transaction of the American Society of Agricul-tural Engineers68:909916.

Newell, P. R., and J. J. Magnuson. 1999. The im-portance of ecoregion versus drainage area on fishdistributions in the St. Croix River and its Wis-consin tributaries. Environmental Biology of Fishes55:24555.

Omernik, J. M. 1987. Ecoregions of the conter-minous United States. Annals of the Association of American Geographers77:11825.

Omernik, J. M., and R. G. Bailey. 1997. Distinguish-ing between watersheds and ecoregions. Journal

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0


14/14


of the American Water Resources Association33:93549.

Pan, Y., R. J. Stevenson, B. H. Hill,and A. T. Herlihy.2000. Ecoregions and benthic diatom assemblagesin Mid-Atlantic Highlands streams, USA.Journalof the North American Benthological Society 19:518

40.Patton, P. C., and V. R. Baker. 1976. Morphometry

and floods in small drainage basins subject to di-verse hydrogeomorphic controls. Water ResourcesResearch12:94152.

Peterson, J. C., J. A. Adamski, R. W. Bell, J. V.Davis, S. R. Femmer, D. A. Freiwald, and R. L.Joseph. 1998. Water quality in the Ozark Plateaus,Arkansas, Kansas, Missouri, and Oklahoma, 199295. U.S. Geological Survey Circular 1158, Denver,CO.

Potter, K. M., F. W. Cubbage, G. B. Blank, and R. H.Schaberg. 2004. A watershed-scale model for pre-dicting nonpoint pollution risk in North Carolina.Environmental Management34:6274.

Rabeni, C. F., and K. E., Doisy. 2000. Corre-spondence of stream benthic invertebrate as-semblages to regional classification schemes inMissouri.Journal of the North American Benthologi-cal Society19:41928.

Ray, R. G., and W. A. Fisher. 1960. Quantita-tive photographyA geologic research tool. Pho-togrammetric Engineering25:14350.

Remshardt, W. J., and W. L. Fisher. 2009. Ef-fects of variation in streamflow and channel struc-ture on smallmouth bass habitat in an allu-vial stream. River Research and Applications 25:66174.

Renschler, C. S., M. W. Doyle, and M. Thoms. 2007.Geomorphology and ecosystems: Challenges andkeys for success in bridging disciplines. Geomor-phology89:18.

Rice, E. L., and W. T. Penfound. 1959. The uplandforests of Oklahoma.Ecology40:593608.

Ritter, D. F., R. C. Kochel, and J. R. Miller. 2002.Process geomorphology.New York: McGraw Hill.

Rohm, C. M., J. W. Giese, and C. C. Bennett. 1987.Evaluation of an aquatic ecoregion classification ofstreams in Arkansas. Journal of Freshwater Ecology4:12740.

Roni, R. 2005. Overview and background. In Moni-toring stream and watershed restoration,ed. R. Roni,111. Bethesda, MD: American Fisheries Society.

Schumm, S. A. 1956. Evolution of drainage sys-tems and slopes in badlands at Perth Amboy, NewJersey. Bulletin of the Geological Society of America67:597646.

Schumm, S. A., and Lichty, R. W. 1965. Time, space,and causality in geomorphology.American Journalof Science263:11019.

Singh, V. P. 1992.Elementary hydrology.EnglewoodCliffs, NJ: Prentice Hall.

Splinter, D. K. 2006. Spatial patterns in the fluvialsystem: Comparisons among three eastern Ok-lahoma ecoregions. PhD thesis, Oklahoma StateUniversity, Stillwater, OK.

Strahler, A. N. 1952. Hypsometric (area-altitude)analysis of erosional topography.Bulletin of the Ge-

ological Society of America63:111742.. 1958. Dimensional analysis applied to flu-

vially eroded landforms. Bulletin of the GeologicalSociety of America69:279300.

. 1964. Quantitative geomorphology ofdrainage basins and channel networks. In Hand-book of applied hydrology, ed. V. T. Chow, 3976.New York: McGraw-Hill.

Urban, M. A., and M. Daniels. 2006. Introduction:Exploring the links between geomorphology andecology.Geomorphology77:2036.

Woods, A. J., J. M. Omernik, D. R. Butler, J. G. Ford,J. E. Henley, B. W. Hoagland, D. S. Arndt, andB. C. Moran. 2005. Ecoregions of Oklahoma (colorposter with map, descriptive text, summary tables,and photographs). Reston, VA: U.S. GeologicalSurvey.

DALE K. SPLINTER is an Assistant Professor in theDepartment of Geography and Geology at the Uni-versity of WisconsinWhitewater, Whitewater, WI

53190. E-mail: [email protected]. His research in-terests include geomorphology, water resources, andhydroecology.

DANIEL C. DAUWALTER was a Graduate Re-search Associate in the Oklahoma CooperativeFish and Wildlife Research Unit and Depart-ment of Zoology, Stillwater, OK 74078. E-mail:[email protected]. He is currently a Fisheries Sci-entist with Trout Unlimited, and his research inter-ests include the spatial analysis of stream habitats and

fishes, stream restoration, and conservation planning.

RICHARD A. MARSTON is a University Distin-guished Professor and Head in the Department ofGeography at Kansas State University, Manhattan,KS 66506. E-mail: [email protected]. His researchinterests include geomorphology, hydrology, andmountain geography.

WILLIAM L. FISHER is Leader of the UnitedStates Geological Survey, New York CooperativeFish and Wildlife Research Unit and an AssociateProfessor in the Department of Natural Resourcesat Cornell University, Ithaca, NY 14853. E-mail:[email protected]. His research interests include fish-eries science, stream ecology, and geographic in-formation system applications in natural resourcemanagement.

Do

wnl

oad

ed

By:[

Marston,

Ri

ch

ard

A.]

At:01

:1114

Decemb

er201

0

watershed morphology & ecoregions

Documents