Hydrologically sensitive areas: Variable source area hydrology implications for water quality risk assessment

M. T. Walter; M. F. Walter; E. S. Brooks; T. S. Steenhuis; J. Boll; K. Weiler

ABSTRACT:

A conceptual approach to assessing water quality risk in the context of variable source area hydrology was developed and applied to the New York City (NYC) water supply watersheds. The term hydrologically sensitive area (HSA) was used to refer to areas in a watershed especially prone to generating runoff that are, therefore, potentially susceptible to transporting contaminants to perennial surface water bodies. As an example, a cost benefit method for quantifying HSAs was developed and applied such that water quality protection was balanced with agricultural needs for NYC watersheds. In accordance with the variable source area concept, the spatial extent of HSAs vary throughout the year. On an annual average, approximately 10% of the watershed is designated HSA and about 20% of the total annual runoff originates on these HSAs. This study is meant to illustrate an approach to dealing with water quality risk assessment.

Footnotes

M. Todd Walter is assistant professor in the department of Environmental Science at the University of Alaska. Michael F. Walter is professor of Agricultural and Biological Engineering at Cornell University. Erin S. Brooks is a Ph.D. candidate in Biological and Agricultural Engineering at the University of Idaho. Tarrmo S. Steenhuis is professor of Agricultural and Biological Engineering at Cornell University. Jan Boll is assistant professor of Biological and Agricultural Engineering at the University of Idaho Kirk Weiler is a research associate in the Agricultural and Biological Engineering department of Cornell University.
Copyright 2000 by the Soil and Water Conservation Society

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