Predicting Background and Risk-based Sedimentation for Forest Watershed Tmdls

The Water Erosion Prediction Project (WEPP) model is a physically-based soil erosion tool developed to predict runoff and erosion. Databases for forest soil, vegetation, and climate conditions have been developed. Background sediment may be generated annually from undisturbed forests, and occasionally following wildfire. In some cases, it may be appropriate to include sediment from essential forest roads with background sediment. WEPP can predict average sediment values, or total maximum daily sediment loads for a given return period. This risk-based capability is of particular importance to watershed managers in sensitive watersheds, including those that have just experienced a wildfire, or have forest management activities dispersed throughout the watershed. The paper will include an example application of the WEPP Model to a sensitive watershed in the Southern California mountains.