Testing the SEDD model in Sicilian basins

Abstract The Sediment Delivery Distributed (SEDD) model combines the universal soil loss equation (USLE) or the revised universal soil loss equation (RUSLE) with a sediment delivery ratio to predict basin sediment yield. The model was applied to seven Sicilian basins, ranging in size from 20 to 213 km2 . Each basin has a reservoir located at its outlet. The model was applied to each basin using a raster scheme, and a subroutine of ArcInfo software to identify the hydraulic path linking each hillslope cell to the nearest stream cell, and to calculate both the travel time and the sediment delivery ratio of each cell. A procedure for estimating the β coefficient, which appears in the expression for determining the sediment delivery ratio of each cell, was developed. As the sedimentation volume for each of the seven reservoirs was known, it was possible to compare measured values with those calculated by the SEDD model. The agreement between measured sediment yield values and calculated ones confirmed the reliability of the proposed estimation procedure and indicates that it should be possible to apply the SEDD model to ungauged basins.