The Use of GIS for Integrated Watershed Analysis

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Virginia Tech

Practitioners of watershed management are increasingly turning to computer models to understand and make decisions about the diverse problems that occur in the watershed. Such models can provide insight into how human interactions with the landscape affect water quality and quantity. Additional modeling tools trace how those effects ripple through ecosystems, economies, and other systems. In the past, models were stand-alone and process-specific, aimed at solving problems related to a narrow discipline. For example, hydrologic models analyzed the quantity of flow through waterways. Separate ecological models probed the cycling of nutrients in those waterways.

An emerging trend for watershed-based models is to link them to a geographic information system (GIS), which provides the basis for integrating data, algorithms, and methods from each discipline of interest. This integration capability makes GIS a very powerful tool for the watershed manager. The GIS in this study within the Upper Roanoke River Watershed integrates modeling efforts from the fields of hydrology, economics, and ecology.

The main goal of this study is to demonstrate the effectiveness of GIS as an integrating and computational aid for making sound decisions about a watershed. A secondary goal is to include GIS functionality in a prototype software application for evaluating the effects of land management decisions. The application, named DesktopL2W, can be a significant tool for choosing how and where development should occur within the boundaries of a watershed.

The three major results of the study are: (1) a library of spatial data that is valuable for watershed analysis; (2) a set of procedures for undertaking a GIS integration project; and (3) the DesktopL2W software product with its usefulness to planners and others who are interested in how development affects the watershed. In addition, discussion of technical issues, such as selection of data formats and spatial and temporal resolution, provides insight into the complexities associated with a GIS integration effort.

environmental modeling, GIS, model integration, watershed analysis