14 gis technologies and their environmental applications · pdf fileaverage annual rainfall in...

Managing ecosystems in a watershed context:

progress made and the emerging role of

integrated spatial information technologies

I. M. Crawford % U. S. Tim', D. K. Jain" & H. Liao*

Department of Agricultural and Biosystems Engineering, Iowa

State University, Ames, Iowa 50011 USA

*Las Vegas Valley Water District, Las Vegas, Nevada 89153 USA

Division ofBiostatistics, South Carolina Department of Health

and Environmental Control, Columbia, SC 29201 USA

E-mail: rente @ iastate. edit

Abstract

Ecosystem management within a watershed context is a relatively newmanagement paradigm that involves: monitoring the current and changingconditions of ecological resources, understanding more fully the structure andfunction of ecosystems to develop improved management options, modeling theresponse of ecosystems to human induced stresses, and assessing the social andeconomic implications of management actions. Watersheds are the mostappropriate ecological and economic unit for carrying out these activities.According to the U.S. Environmental Protection Agency, managing naturalresource programs on a watershed basis "makes good sense - ecologically,financially and socially." While there is a broad consensus on the utility of awatershed approach most recognize that contemporary ecosystem managementcan benefit significantly from recent developments in integrated spatialinformation technologies. This paper examines major issues related to theapplication of CIS in watershed management. Specifically the paper presents anddiscusses the progress made during the past several decades in developing newtools to enhance predictive understanding of watershed ecosystems. The paperalso introduces the application of CIS and environmental modeling in two casestudies: a spatial decision support system for managing integrated livestock-cropproduction in agricultural watersheds and an interactive watershed hydrologicmodeling environment used to estimate the impacts of agricultural managementsystems on hydrology and water quality.

Transactions on Information and Communications Technologies vol 18, © 1998 WIT Press, www.witpress.com, ISSN 1743-3517

14 GIS Technologies and their Environmental Applications

Introduction

Water quality problems have received increased national andinternational attention, with agricultural runoff identified as the majorsource of non-point pollution in lakes, rivers, and estuaries. World-wide,impaired waters from non-point source pollution accounts for millions ofpeople suffering from disease, billions of dollars in lost economicdevelopment, and trillions of dollars in the cost of implementing remedialpractices (Dude, 1993). It has been estimated that 30-50% of the earth's

land and water resources are affected by non-point source pollution(Pimentel, 1991). Along with increased awareness of these trends hascome a nation-wide concern for the preservation of healthy aquaticecosystems. Watershed management has been praised by some forbringing the cutting-edge science back to water quality management(Sheng, 1990). One of the main advantages of a watershed managementapproach is that it provides the most effective method to addresspersistent problems such as non-point source pollution and habitatdegradation. Understanding the interrelationships between watershed

components is needed to ensure a vital ecosystem. Many natural resource

agencies advocate managing land at a watershed scale as an efficientapproach to alleviate agricultural non-point source pollution problems.These agencies often depend on integrated spatial informationtechnologies to combine, manage, model, and display the large quantitiesof data and to evaluate the impacts of land use changes on watershedwater quality.

Spatial information technologies such as remote sensing, globalpositioning systems (GPS) and geographic information systems (GIS)have provided a myriad of operational and strategic management tools toassist in resource management. In particular, the GIS technology providesa cost-effective tool for acquiring resource management data and forevaluating the implications of different land use practices on watershedwater quality. GIS has become an important tool in the storage,manipulation, and presentation of large amounts of spatial and non-spatial data that describe watershed land use, vegetation cover, soils,topography, climate, and hydrogeologic conditions. GIS allows the userto analyze and display spatially referenced data, and provides aninteractive environment to construct models and to make the modelseasier to use (Goodchild et at., 1996). Coupling GIS with environmentalsimulation models and expert systems provides an efficient spatialdecision support system (SDSS) to assess the implications of differentwatershed management alternatives on aquatic ecosystem function.


GIS Technologies and their Environmental Applications 15

The purpose of this paper is to explore the emerging role ofintegrated spatial information technologies and to examine the progressmade so far in developing new tools and decision support systems toenhance the management of watersheds. Specifically, the paper reviewsresearch related to the coupling of GIS with environmental models forwatershed ecosystem management; the development of graphical userinterfaces (GUI) to enhance the use of ecological models; and the futuretrends in the use of GIS in managing ecosystems. Two case studies arepresented to demonstrate the role of GIS in managing watersheds withinthe ecosystem context.

Background

Significant progress has been made in coupling GIS with environmentalsimulation models for natural resource management. For example,Srinivasan and Arnold (1994) described the tight coupling of the Soil andWater Assessment Tool (SWAT) with GRASS GIS to facilitate basin-scale analysis of water quality. Vieux (1991) coupled a distributedhydrologic model with GIS to predict overland flow and water quality in

an agricultural watershed. Yoon (1996) developed a method for directlylinking the agricultural non-point source pollution (AGNPS) model witha GIS and a relational database management system. The strategy forintegrating environmental simulation models with GIS can range fromloose coupling through the exchange of data files to tight coupling wheremodel algorithms are embedded within the GIS using programminglanguages (Maidment, 1993; Tim, 1996). Under the loose couplingstrategy, data generated by the GIS is organized as input to the simulationmodel while the output data from the environmental model is analyzedand reformatted for display by the GIS. The close coupling strategymakes use of scripts written using standard programming languages (e.g.C++, Java, and Arc Macro Language) to organize complex modelingcommands and operations.

Progress has also been made in the development of efficient userinterfaces to facilitate the implementation of environmental simulationmodels. Meiner (1996) presented the integration of a vector-based GISand non-point source pollution model by using macros and menu files tocreate a menu-driven interface. Loucks (1993) explored the potential forincorporating video and sound within GIS-based simulation models. Spellet al. (1997) developed an interactive user-friendly, flexible GIS sitesuitability model to be used for wetland protection and restoration. Userinterfaces that are based on the windows-icons-mice-pointers (WIMP)interface provide decision-makers with sophisticated and easy-to-use



modeling environments to perform "what if analysis. Recentadvancements in GIS include the development of the Avenueprogramming language (Environmental Systems Research Institute,

Redlands, CA) to provide an intuitive GUI within ArcView allowing non-technical GIS users to manipulate complex environmental models. DiLuzio et al. (1997) developed and used a user interface for ArcView GISand SWAT (Soil and Water Assessment Tool) water quality model tosimulate the hydrology, soil erosion, and sediment transport in a Texaswatershed.

The future of GIS in watershed management looks good. A numberof factors have made it increasingly easier to collect, manage, process,share and display spatial and non-spatial data. These factors include fasterand cheaper computing, the shift from mainframe to desktop computers,the development of the Internet, Intranet, and World Wide Web, and themany breakthroughs in information and communication technologies. Inthe past, error and uncertainty associated with poor data have adverselyimpacted the reliability of the modeling results and hence the quality ofmanagement decisions. Various studies have been conducted to review

the issue of accuracy in GIS modeling application and determine theappropriate spatial scales for watershed model validation (Wagenet andHutson, 1996, Inskeep et al., 1996, and Wilson et al., 1996).

Case Studies

Given the important role of spatial information technologies inenvironmental and natural resource management, numerous integrateddecision support systems have been developed. Fedra (1993) developed aset of interactive ground water models for the management of hazardouswaste, site selection, and risk assessment of landfills. Frysinger et al.(1993) described a set of environmental decision support systems tofacilitate human decision making with respect to the hydrological aspectsof hazardous waste management. In this section, two case studies thatinvolve the integration of environmental models with GIS for watershedmanagement are discussed. Both case studies examine water quality andnon-point source pollution in the Lake Icaria watershed.

The Lake Icaria watershed is located in Adams County, Iowa,approximately 120 kilometers southwest of Des Moines. The watershedhas an area of 7,075 hectares and contributes flow to Lake Icaria.Average annual rainfall in the watershed is 84 cm with the greatestamount of 14 cm occurring in June. Agricultural activities in the LakeIcaria watershed consists of row crops integrated with livestockproduction. Cropland and pastureland comprise 49% and 22.4% of the



watershed area, respectively, while 11.6% of the watershed is under thecropland reserve program. About 4.6% of the watershed area is identifiedas idle land, which includes irregularly shaped tracts of land and parts ofcroplands that are either non-farmable or unsuitable for pasture.Farmsteads, roads and parkland occupy the remaining 12.4% of the LakeIcaria watershed.

Case Study 1

This case study focuses on the development of a spatial decision supportsystem (SDSS) to facilitate analysis of environmental pollution problems(e.g. water quality degradation) associated with integrated crop-livestockproduction. The system described extensively in Jain (1995) integrates a

biophysical simulation model, knowledge-based system, and ARC/INFO(Environmental Systems Research Institute, Redlands, CA) GIS toevaluate the impacts of alternative nutrient management practices in crop-livestock production. Mathematical modeling of nutrient flows in theenvironment is used for the selection and optimum design of managementstrategies. The livestock production planning and site selection spatialdecision support system described in this paper combines the hierarchicaloptimization technique and spatial weighting scheme, spatial databases,and ARC/INFO GIS to facilitate the trade-off between livestockproduction expansion (and economic development) and environmentalquality. The biophysical modeling component utilizes the NLEAP model(Shaffer, 1991) to estimate nitrate loading to groundwater beneathagricultural areas and to determine the effectiveness of alternativeagricultural management practices. The spatial modeling componentadopts the multi-criteria evaluation technique to delineate optimal landareas to site livestock production units and areas for manure application.The knowledge base component was written in LISt Processing (LISP)language and was based on the Induction Dichotomy (specifically IDS)decision-tree algorithm. An associational rather than positionalrepresentation was used in the ID3 decision tree algorithm (Quinlan,1986) to allow the input parameters to be uniquely specified to facilitateuser-initiated query. The knowledge-base of nitrate leaching wasdeveloped by using simulation results from the NLEAP model for variouscombinations of soils, land management, topography, and climate (Jain,1995).

When applied to the Lake Icaria watershed, the spatial decisionsupport system showed great promise as a cost-efficient and effective toolfor addressing some of the environmental problems associated withlivestock production. Figure 1 shows the spatial distribution of total



nitrogen loading to the Lake Icaria watershed when manure generated

from hog units were applied to crop fields surrounding the animal

facilities.

Figure 1. Spatial distribution of total nitrogen loading for Lake Icariawatershed

Case Study 2

This case study focuses on the development of an integrated spatialdecision support system for non-point source pollution control andwatershed management. The system is a tight coupling between theAGNPS water quality model and ARC/INFO GIS. The AGNPS model(Young et al., 1989) is a distributed parameter model developed toevaluate the soil and water quality conditions of and agriculturalwatershed and to estimate the impacts of agricultural managementsystems on hydrology and water quality. The model divides a watershedinto uniform grid cells which facilitates analysis of spatially variableprocesses and their effects on watershed water quality. All twentydifferent input parameters required by the AGNPS model are defined atthe grid-cell level, and the runoff, sediment, and pollution loads generatedin each grid cell are routed to the watershed outlet. Results from anAGNPS model simulation can be used to: characterize diffuse sources of



pollution within a watershed, assess the effectiveness of differentwatershed reconfiguration and land management strategies, and providethe framework for formulating environmental policy and managementdecision-making.

The interactive modeling system developed in ARC/INFO GIS wasused to target the critical areas of nitrogen loading at a watershed scale.Figure 2 depicts the simulation results from the modeling system,expressed in terms of the spatial distribution of nitrogen loading in boththe adsorbed and dissolved phases. Coupling the AGNPS model withGIS technology incorporated the spatial variability of landscapeproperties in the modeling process, making it more efficient and intuitive.

N In dissolved phase

Figure 2. AGNPS simulation of Nitrogen loading in adsorbed anddissolved phase.

The two case studies described the components of integrated spatialdecision support systems for non-point source pollution control andenvironmental management. The successful coupling of environmental



decision tools with GIS to form management decision support systemsfor managing ecosystems within watershed boundaries providesmanagers and decision-makers with the means to make environmentallysound decisions about watershed water quality.

Summary

The widespread adoption of GIS has contributed significantly to themanagement of natural resources within a watershed context. This paperexamines major issues related to the application of GIS in watershedmanagement. The role of GIS is specifically looked at as a cost-effectivetool for evaluating the impacts of land management practices in awatershed. This paper reviews research related to the coupling of GIS

with environmental simulation models and the development of GUIs astwo methods to enhance the use of ecological models for watershedmanagement. It is evident that spatial information technologies inwatershed management, specifically non-point source pollution, havemuch to contribute to resource management by providing the toolsneeded to manage, manipulate and store the spatial and non-spatial dataneeded for watershed management. In this paper we presented two casestudies describing the components of integrated spatial decision supportsystems for non-point source pollution control and environmentalmanagement.

References

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