Working with WhAEM2000: Capture Zone Delineation for a City Wellfield in a Valley Fill Glacial Outwash Aquifer Supporting Wellhead Protection

摘要

The purpose of this document is to introduce through a case study the use of the groundwater geohydrology computer program WhAEM for MicrosoftWindows (32-bit), or WhAEM2000. WhAEM2000 is a public domain, ground-water flow model designed to facilitate capture zone delineation and protection area mapping in support of the state's and tribe's Wellhead Protection Programs (WHPP) and Source Water Assessment Planning(SWAP) for public water well supplies in the United States. Program operation and modeling practice is covered in a series of progressively more complex representations of a well field tapping a glacial outwash aquifer. WhAEM2000 provides an interactive computer environment for design of protection areas based on simple WHPAs (e.g., radius methods, well in uniform flow solutions), and geohydrologic modeling methods. Protection areas are designed and overlaid upon US Geological Survey Digital Line Graph (DLG), Digital Raster Graphic (DRG) or other electronic base maps. Geohydrologic modeling for steady pumping wells, including the influence of hydrological boundaries, such as rivers, recharge, no-flow boundaries, and in homogeneity zones, is accomplished using the analytic element method. Reverse gradient tracelines of known residence time emanating from the pumping center are used to delineate the capture zones. WhAEM2000 has import and export utilities for DXF files and Shapefiles. WhAEM2000 has on-line help and tutorials. Install scripts and base maps are available for download from the EPA Center forExposure Assessment Modeling web site (www.epa.gov/athens/ software/whaem/index.html).