Watershed Nonpoint Source Pollution Assessment Using AGNPS/ARCVIEW Integrated System

A GIS-based AGNPS modeling system, a system of ArcView scripts and associated controls, has been developed for assessing nonpoint source pollution at the watershed scale. The integrated GIS modeling system can estimate runoff and pollutant loading from a watershed, allows users to make a detailed comparison of the effects of diverse land uses, landscape features, and land management scenarios on water quality in a designated watershed. A map-based display of AGNPS modeling outputs, rather than a numerical text file from the model, provides critical areas of erosion and pollutant movement within the watershed. This paper describes the development of an integrated system that uses object-oriented Avenue language and Visual Basic language. The system provides a user-friendly interface with pre-processor and post-processor for the AGNPS model. This new approach allows the application of a more comprehensive model that previously could not have been discretized to such a high level of detail. This integrated system was applied to a coastal plain watershed to demonstrate its capabilities.