The GeoWEPP Interface for ArcView 3.x (GeoWEPP ArcX) is an ArcView project that starts up with a user-friendly wizard to integrate own raster-based Digital Elevation Models or those from publicly available sources (USGS 1:24,000 Quads only).
The GeoWEPP wizard allows the user to go through three essential steps to derive topographical input parameters for a WEPP watershed simulation:
Step 1: Import of DEM and Area of Interest
The first step in the wizard allows the import of Digital Elevation Models by downloading and importing interactively USGS datasets. This procedure also enables the user to automatically merge adjacent DEM quad sheets. The next wizard screen allows interactively to download a digital topographical map (called Digital Raster Graph). The image will be used as an transparent overlay for the DEM imported in the previous step which allows the user to locate the area of interest.
Step 2: Channel and Watershed Delineation
After importing the relevant information a channel delineation takes place in the following step. Channel parameters and a watershed outlet cell have to be set for TOPAZ to delineate drainage pattern and a watershed with sub-catchments.
In the final step the wizard let the user set the input parameters for the WEPP model. The user has to specify beside the climate station the main soil, land use and channel parameter sets for the entire watershed and optionally for the delineated sub-watersheds. After running a WEPP watershed simulation (for representative hillslopes in a watershed) and/or the flowpath method for WEPP (merged hillslope simulations for all flowpaths into a watershed’s channel network) the results are mapped as a relative measure to a tolerable soil loss or Target value (T). The detailed simulation results for the watershed simulation is also given in a text file.