WEPP predicts the distribution of erosion on a hillslope as well as the runoff amount and sediment yield from each storm that occurs during a multiyear period. For every storm, WEPP calculates the infiltration and runoff, and soil detachment, transport, deposition, and delivery from the bottom of the hillside. Researchers have measured WEPP erodibility values for cropland soils, rangelands, and forest roads, harvest areas, and burned areas. To date, WEPP has been validated for some cropland conditions, and forest roads.
Work is ongoing for rangelands and other forest conditions.
The WEPP model is run for a number of years with a daily climate input typical of the area of interest. The user can describe the topography in detail, provide a soil description, and describe the amount and shape of vegetation in detail. Actual vegetation growth is moderated by the temperature, radiation, and availability of soil water. All files are built with the aid of character-based file builders. This feature allows users to model common conditions such as roads above riparian areas, or variation in the severity of a fire along a hillslope.