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U.S. Geological Survey
Professional Paper 1645

An Interdisciplinary Assessment of Regional-Scale Nonpoint Source Ground-Water Vulnerability: Theory and Application

By Richard L. Bernknopf, Laura B. Dinitz, and Keith Loague


Aerial photograph looking down on Pearl Harbor showing three main arms and one main outlet
Aerial photograph of the Pearl Harbor basin on the island of O’ahu, Hawaii


The availability of potable ground-water supplies is a major environmental quality and human health concern throughout the United States. In the study reported here, a geographic information system (GIS) environment is used to apply an Integrated Earth Science–Economics Model (IESEM) that combines a regional-scale, nonpoint source vulnerability assessment tool with a specific remediation measure to avoid unnecessary agricultural production costs related to the use of agrochemicals. Based on two screening indices that utilize earth science information, the vulnerability assessment tool functions in a spatial analysis to target areas vulnerable to ground-water contamination. This coordinated approach forms the core of a risk-based regulatory standard for the application of agrochemicals.

The application of the IESEM in a cost-effectiveness analysis for 17 coordinated programs showed that 12 of the programs demonstrated substantial cost savings, ranging from $8.0 million to $244.0 million, that could accrue to producers if a regional vulnerability assessment were coordinated with a wellhead treatment program. The coordinated approach was not cost effective for the remaining five programs. The case study was conducted for the Pearl Harbor basin on the island of O’ahu, Hawaii. The IESEM approach was developed as a spatial analysis tool to estimate the benefits of an information-based approach to decision making.

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Please send comments and suggestions, or report problems, to: Michael Diggles
Created: February 26, 2002 (cad)
Updated: February 15, 2007 (bwr, mfd)