Predicting the effect of slope gradient on soil erosion rates for steep landscapes

摘要

The effect of slope gradient on soil erosion rates was investigated using simulated rainfall applied to laboratory flume plots at slopes from 5 to 30 percent. Both the experimental data and the literature strongly support a logistic function of the sine of the slope angle of the form S = A + B/[1 + exp (C -D sin theta)] where S is a slope adjustment factor and A, B, C & D are coefficients that depend on the relationship between erosive stress, soil cohesion, and sediment properties. The average effect of slope gradient on intcrill-only erosion differed significantly from the literature, however when interill+rill processes were present the average effects were consistent with published functions. The effect of slope on individual soils varied dramatically from a 2.5 fold to a 50 fold increase in sediment delivery over the range of slopes studied, and was found to be inversely related (log-log linear) to the dispersed silt and clay content, and silt content, of the soil.