Comparative Prioritization of Watershed Vulnerability: A Surrogate Approach Using Macro-Cultural Variables and Geographic Information Systems

Hari Gurung
UNIVERSITY OF GEORGIA

Watershed is increasingly becoming an important environmental management unit, a surrogate for ecosystem. Watershed is the basis for United States Environmental Protection Agency's environmental management policies and plans. However, the current approach to determining watershed degradation is, largely, based upon high resource demanding-time, money and human-and tedious chemical testing methods and procedures. Since the causes of watershed degradation are largely anthropogenic in nature, this paper attempts to prioritize watershed degradation/vulnerability based upon anthropogenic pressure as defined by a set of twelve spatially-referenced variables, which I call macro-cultural variables. The variables are: human population density per mile2, number of dam sites, number of solid waste landfills, number of industrial discharge facilities, number of manufacturing businesses, animal density per mile2, city area mile2, percentage forest area, percentage wooded area, percentage crop area, road-length/mile2, and number of toxic-release sites.

The approach is demonstrated using watershed-level variables/data on the Upper-Oconee River Watershed, Georgia from the Georgia GIS Clearinghouse. The data are extracted then disaggregated to sub-watershed level data using GIS software, for analyses. Cluster analysis and factor analysis was done to demarcate sub-watershed clusters of various levels of degradation, and the underlying causal factor-constructs, respectively. The analysis successfully classified the 16 sub-watersheds into three clusters, viz. high, medium and low anthropogenic- pressured categories. These were then mapped using GIS software to depict the spatial distribution of sub-watershed vulnerabilities. The method, though dirty, is quick and can provide a basis, through prioritization of sub-watersheds, for watershed and/or environmental management and planning.