Soil erosion model predictions using parent material/soil texture-based parameters compared to using site-specific parameters

Forested areas disturbed by access roads produce large amounts of sediment. One method to predict erosion and, hence, manage forest roads is the use of physically based soil erosion models. A perceived advantage of a physically based model is that it can be parameterized at one location and applied at another location with similar soil texture or geological parent material. To test this perception, a two-part study was conducted to compare soil erosion model predictions using parent material/soil texture-based parameters to predictions using site-specific parameters. The first step was to determine site-specific erosion parameters using rainfall simulation. The second step was to compare erosion model results for a typical road network using the two parameter sets. Lake Tahoe was chosen for the study because it had parent materials similar to sites where parameterization had been performed. The coefficient of variation in runoff and sediment mass from the Lake Tahoe rainfall simulations varied from 8% to 36%. These values, although smaller than those reported from natural rainfall studies, are an indication of the inherent variability of erosion measurements.