Slope curvature influence on soil erosion and deposition processes

Sediment water quality problems are not necessarily the direct result of er osion from the most intense soil erosion areas. A study of within-basin var iability of the sediment delivery processes is needed to identify areas whe re the most effective soil conservation strategies should focus. In this pa per the sediment delivery processes is examined along the hydraulic path fr om sediment source areas to the nearest stream reach. The effects of shape (convex, concave, and uniform) of the hydraulic path are modeled using a po wer equation for slope profile and revised universal soil loss equation (RU SLE) with two different expressions of the topographic factors. A criterion is proposed for the erosion active slope length, i.e., the slope length in which no deposition processes occur. Then, using the continuity equation f or sediment transport, a Psi factor is deduced to correct the topographic f actors of RUSLE and those proposed by Moore and Burch [1986], depending on slope curvature. Finally, two relationships for correcting the topographic factors for an irregular slope are experimentally tested comparing the calc ulated sediment yields with net soil erosion values estimated by the propor tional method of Martz and de Jong [1987] and cesium 137 data available fro m a Sicilian basin.