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Environmental Protection Agency WhAEM 2000 OVERVIEW  

WhAEM2000 is a groundwater flow model designed to facilitate delineating capture zones and mapping well head protection areas (WHPAs). WhAEM2000 provides an interactive computer environment to design protection areas based on simple WHPAs and geohydrologic modeling methods. WHPAs are designed and overlaid on electronic U.S. Geological Survey base maps. Geohydrologic modeling for steady pumping wells is accomplished using the analytic element method, which can incorporate the influence of hydrological boundaries, such as rivers, recharge, no-flow boundaries, and inhomogeneity zones. Reverse gradient tracelines of known residence times emanating from the pumping center are used to delineate the capture zones.


WhAEM 2000_Home
  • Visualization
  • Modeling
    • Capture Zone Delineation
  • Tabular File: tx, wl, tp
  • Graphical File: *.bbm, *.dxf, *.dwg, *.shp, others
  • Output
    • Tabular File: N/A
    • Graphical File: *.bln, *.grd, *.dxf, *shp
    • Any conservative (non-reactive) solutes
    • Groundwater
    Technical Team Members
    • Hydrogeologist
    WhAEM 2000 - installation
    • Base maps that are required to run the tutorial are not included with the executable file for software installation. The zip file that contains the base maps is called "tutorial maps" and is also available for download at the WhAEM 2000 home page.
    WhAEM 2000 - data loading
    • Data (labels, pumping well data and test points) are loaded as ASCII text files, with the following extensions: *.tx for labels, *.wl for well data, and *.tp for test point data. Test points are head measurements at observation wells that are used in model calibration.
    WhAEM 2000 - graphic loading
    • Although many types of files may be imported to WhAEM 2000, the quickest and easiest way to generate base maps is by using the binary base map (BBM) utility that can be accessed at the WhAEM 2000 home page. Selecting the BBM utility takes the user to an interactive map selection tool that is easy to navigate if the user has basic geographic information about the site (state and county, for instance). The utility will generate a map based on U.S. Geological Survey digital line graphic (DLG) map coverage.
    WhAEM 2000 - logical flow
    • Although the layout and organization of menus, toolbars, and buttons is similar to other modeling packages, the software does not seem to be organized to facilitate use without first reading the manual or completing the practice exercises included with the manual (Kraemer and others 2005).
    WhAEM 2000 - expert knowledge
    • User should have a sound understanding of hydrogeologic concepts. Previous modeling experience, while not required, is a plus.
    • User should understand the limitations and assumptions of modeling using analytical elements. WhAEM 2000 is a single-layer, steady-state flow model. Hydrogeologic parameter values can be varied between regions that the user delineates through elements called "inhomogeneities." Depending on the complexity of the site or the level of sophistication required, the modeler may be better served using a three-dimensional numerical model such as MODFLOW. Even in these cases, however, analysis in WhAEM 2000 may enable the user to better refine the conceptual model before a MODFLOW project is undertaken.
    WhAEM 2000 - functionality
    • The user is provided with three layers of redundancy for many functions: toolbar buttons, menu items, and right-click pop-up boxes may be used to initiate many actions. Model elements (wells, line sinks, and inhomogeneities) are easy and straightforward to add. Well data may also be read into the model by loading ASCII files.
    • Graphical capabilities are fairly advanced for freeware. No glitches were encountered when plotting maps.
    • The model is calibrated by importing "test points," which are observation well locations and associated water levels. When the model is solved, the residuals are posted at test points throughout the display area, using an upward- or downward-pointing triangle as a marker. The markers are scaled to the magnitude of the residual (the difference between the observed and simulated values). Unfortunately, it is easy for the triangles to blend into the base map.
    • WhAEM 2000 provides additional tools to evaluate calibration and model results, including calibration statistics and tables that provide model residuals and model element data (Model>View) and tools to evaluate recharge and discharge conditions at line sinks (View>Results Overlay).
    • WhAEM 2000 provides multiple methods for capture zone delineation, including arbitrary fixed radius, calculated fixed radius, well in a uniform flow field, and geohydrologic modeling (analytical element modeling with capture zones delineated through particle tracking). WhAEM 2000 provides an interface that is designed to evaluate the adequacy of these approaches by overlaying the capture zones delineated from the various approaches on the same screen.
    WhAEM 2000 - documentation
    • A manual and tutorial may be downloaded from the WhAEM 2000 web site. Working through the tutorial is recommended. The tutorial consists of six chapters that guide the user through progressively more complex applications of WhAEM 2000 and provide insight on both the modeling process and the application and evolution of well head protection methodology. An experienced modeler should allow 6 to 8 hours to complete the exercises. Less-experienced or novice modelers may require twice as long.
    WhAEM 2000 - output
    • Contours, pathlines, and capture zones may be output for post-processing in more sophisticated graphical platforms such as AutoCAD, ArcGIS, and Surfer.
    • The user can view model results tables, calibration statistics and model run files after each run using the various Model>View commands available in the Model menu.  Tables can be output to Excel using the Edit>Copy command in the pop-up viewer windows.
    WhAEM 2000 - sources
    • WhAEM 2000, Version 3.2.0 (updated June 2005), downloaded November 2, 2006.
    � Kraemer, S.R., H.M. Haitjema, and V.A. Kelson 2005. Working with WhAEM2000: Capture Zone Delineation for a city Wellfield in a Valley Fill Glacial Outwash Aquifer Supporting Wellhead Protection. EPA/600/R-00/022 updated June 2005
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