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 damagi ng storm. This storm, based on long term sediment records from 3 Wyoming st reams, produced approximately 18 mm of precipitation in 15 min with an inte nsity of 97 mm hour(-1). The rainfall simulator covered 2 plots; each 0.6 b y 2 m, Plots were on 9% slopes with highly erosive soils (silt and fine san d texture) on native rangeland in 3 areas of Wyoming, Cover and surface rou ghness were measured with a point frame. Sediment production typically peaked approximately 120 sec after runoff sta rted and reached steady state within 6 min. Plots with no cover (tilled) se ldom produced runoff due to high infiltration and the short duration rainfa ll, Sediment yield was moderately correlated with total cover for total cov er less than 30%, and sediment yield decreased to 0.1 tonnes ha(-1) (assume d allowable soil loss) or less for greater than 30% cover. There was a weak correlation between surface roughness and sediment yield, and surface roug hness was slightly correlated with total cover. These results suggested tha t maintaining at least 30% total cover could control sediment yields from s hort duration-intense storms. Experimental results also indicated considera bly higher sediment yields than those predicted by the Revised Universal So il Loss Equation or a modified version of that equation.