The United States Department of Agriculture (USDA) Agricultural Research Service (ARS) is developing a new erosion prediction technology to replace the Universal Soil Loss Equation (USLE) as the primary means of prediction soil erosion by the Soil Conservation Service (SCS) and other agencies, including the Bureau of Land Management, and the Forest Service (Foster, 1987).
A set of equations to define erosion processes has recently been developed (Meyer and Wischmeier, 1969; Foster and Meyer, 1972a; Foster et al., 1976; Foster, 1987). These equations have generally given more consistent estimates of water erosion, and allow the estimation of erosion on an individual storm basis. They separate water erosion into rill and interrill components, and then combine the results to calculate total erosion on a storm-by-storm basis over the entire growing season. This modeling approach allows application to a greater diversity of climates, as well as improved consideration of topography, seasonal changes in crop growth, soil moisture, and residue cover.
The USDA has decided to adopt the rill/interrill erosion prediciton technology in the form of a user-friendly computer program to replace the USLE. The ARS was given the responsibility for developing this computer technology, in a project known as the Water Erosion Prediction Project (WEPP) (Foster, 1987). Existing methods for determining the susceptibility of soil to rill and interrill erosion were not adequate for the WEPP model (Foster et al., 1976; Wischmeier, 1976), so in 1985, the ARS began planning a field research project to measure the on-site erodibility of soils.
The objectives of this compendium are to:
