Modeling Conservation Practices with RUSLE2.

New techniques allow RUSLE2 to estimate average monthly runoff, the number of runoff events per year, and parameters describing the statistical distribution of runoff event depths for any combination of location, soil, and management. This allows the determination of runoff events of specific return periods and erosion computation during an accounting period for a representative sequence of runoff events that is based completely on existing RUSLE2 input information. Further, the RUSLE2 code has been modified to allow efficient grid-based sheet and rill erosion computations that can be driven by high-resolution elevation data. Local slope length is determined using the ratio of runoff entering a cell to that leaving the cell, thus reflecting upslope variation in soil and land use. Surface roughness, residue cover, and soil biomass properties are re-used for each combination of soil and management, creating computational efficiency. These developments overcome the limitations of having to describe a site as a series of one-dimensional representative profiles and allows RUSLE2 erosion and sediment delivery computations to be applied in a GIS context. Work is underway to add the capability of predicting concentrated flow erosion using process-based equations.