Estimation of Groundwater Pollution Potential by Pesticides in Mid-Atlantic Coastal Plain Watersheds

A simple GIS-based transport model to estimate the potential for groundwater pollution by pesticides has been developed within the ArcView GIS environment. The pesticide leaching analytical model, which is based on one-dimensional advective-dispersive-reactive (ADR) transport, has been directly integrated into the GIS with menu interface and display tools to estimate the spatial and temporal distribution of a potential pesticide's emission to groundwater. The ADR model was chosen because it requires readily available data as compared to other non-GIS models and it has the potential to handle multiple soil profile descriptions. The ADR model has been used to assist with pollution assessment such as the location and timing of pesticide spreading on watersheds, or choosing the most effective "Best Management Practices". By embedding ADR modeling capabilities into the GIS, one is able to evaluate the groundwater vulnerability to pesticide contamination on a large scale where variable source areas are responsible for a part or all of the groundwater contamination. To demonstrate the GIS-based contaminant transport model and its capabilities, the program was applied to Mid-Atlantic coastal plain agricultural watersheds, which are particularly vulnerable to agricultural pesticide pollution.