USDA PROCESS-BASED TOOLS FOR ESTIMATING RUNOFF, SOIL LOSS, AND SEDIMENT YIELD – THE WEPP MODEL

The Water Erosion Prediction Project (WEPP) was initiated in 1985 with the goal of developing next generation erosion modeling technologies for use by soil conservationists, researchers, and other national, state, and local agencies engaged in estimating levels of soil erosion by water and sediment losses. The WEPP model is based upon the fundamentals of hydrology, hydraulics, and erosion mechanics science, and includes a range of physical process representations to allow for simulation of other relationships which impact the water balance – such as soil disturbance and consolidation, plant growth, residue decomposition, and irrigation. WEPP is a process-based, distributed parameter, continuous simulation erosion prediction model. It was first publicly released in 1995 at a special Symposium of the Soil and Water Conservation Society in Des Moines, Iowa. At that time the validated and documented Fortran science model was provided with a simple DOS-based user interface. Since then, additional functionality as well as user interfaces and databases have been developed, including a stand-alone Windows version for use on personal computers (PC) for simulation of hillslope profiles and small, simple watersheds. For application to larger, more complex watersheds, use of spatial topographic, soil, and landuse information is the most practical approach, using the GeoWEPP interface, which is an ArcView/ArcGIS extension. Most recently, web-based interfaces for WEPP have been developed, requiring only that a user have a PC connected to the internet. Data for climate, soils, topography, landuse, and spatial images are either kept on the National Soil Erosion Research Laboratory (NSERL) servers or accessed from other locations and data servers online. Simple hillslope simulations can be run for any location in the US, as well as much more complex watershed applications. This presentation will provide information on and example applications of the WEPP model.