Slope curvature influence on soil erosion and deposition processes

Abstract

Sediment water quality problems are not necessarily the direct result of erosion from the most intense soil erosion areas. A study of within‐basin variability of the sediment delivery processes is needed to identify areas where the most effective soil conservation strategies should focus. In this paper the sediment delivery processes is examined along the hydraulic path from sediment source areas to the nearest stream reach. The effects of shape (convex, concave, and uniform) of the hydraulic path are modeled using a power equation for slope profile and revised universal soil loss equation (RUSLE) 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 for sediment transport, a Ψ factor is deduced to correct the topographic factors 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 calculated sediment yields with net soil erosion values estimated by the proportional method of Martz and de Jong [1987] and cesium 137 data available from a Sicilian basin.