Upland erosion under a simulated most damaging storm

A 2 year study was conducted to determine the effects of surface cover and roughness on sediment yield from plots subjected to a simulated most damaging storm. This storm, based on long term sediment records from 3 Wyoming streams, produced approximately 18 mm of precipitation in 15 min with an intensity of 97 mm hour(-1). The rainfall simulator covered 2 plots; each 0.6 by 2 m, Plots were on 9% slopes with highly erosive soils (silt and fine sand texture) on native rangeland in 3 areas of Wyoming, Cover and surface roughness were measured with a point frame. Sediment production typically peaked approximately 120 sec after runoff started and reached steady state within 6 min. Plots with no cover (tilled) seldom produced runoff due to high infiltration and the short duration rainfall, Sediment yield was moderately correlated with total cover for total cover less than 30%, and sediment yield decreased to 0.1 tonnes ha(-1) (assumed allowable soil loss) or less for greater than 30% cover. There was a weak correlation between surface roughness and sediment yield, and surface roughness was slightly correlated with total cover. These results suggested that maintaining at least 30% total cover could control sediment yields from short duration-intense storms. Experimental results also indicated considerably higher sediment yields than those predicted by the Revised Universal Soil Loss Equation or a modified version of that equation.