Wellhead Protection Area Delineation: Linking Flow Model with GIS

Abstract

The protection of areas that contribute water to public wells (wellhead protection areas or WHPAs) is an important component of the Rhode Island Department of Environmental Management (RIDEM) ground‐water protection strategy. An accurate, scientifically based WHPA delineation is the first step in wellhead protection. RIDEM has chosen to use the Uniform Flow analytical model, in conjunction with hydrogeologic mapping, for WHPA delineation around large public supply wells completed in stratified drift in Rhode Island. Geographic information system (GIS) calculates variables for input into the model, transforms model output into geographically referenced data layers, and provides mylar overlays for final hydrogeologic mapping of the WHPA. RIDEM hydrogeologists provide study area boundaries, run the model on a personal computer‐ (PC‐)based program, and delineate the final WHPA on mylar overlays. Maps of the WHPAs and other hydrogeologic data will be provided to communities and water suppliers and will be the basis for local wellhead protection planning required under the Rhode Island Wellhead Protection Program.