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erosion has ever been seen on the site and no sediment delivery to the pond has ever <br />occurred. <br />The Universal Soil Loss Equation was developed in 1965 by Wischmeier and Smith <br />using earlier equations by Musgrave in 1947. The equation was modified in 1993 to <br />account for steeper slope areas, change in erosion over time among other improvements. <br />The revised equation (RUBLE) does account for rill and inter-rill erosion. Its complete <br />form is listed below: <br />A=RxKx(LxS)xCxP <br />where: <br />A =soil loss in tons/year per acre <br />R =rainfall factor (from standard chart of area) <br />K =soil erodibility factor (function of site specific soil) <br />LS =length slope factor (from contour map & chart) <br />C =management factor dependent upon vegetation & mulch <br />P =erosion control practice factor <br />Rainfall Fac[or "R" <br />The rainfall factor is the product of rainfall energy times the maximum 30-minute <br />intensity for a given rainstorm. It is considered as the erosive power of [he rain fot [hat <br />particular area. A chart of "R" values for Colorado developed by the Transportation <br />Research Board in 1980 shows that the "R" value for the entire Oak Creek area is 26. <br />For a discussion of this adjustment to the rainfall factor, see Design Hydrology and <br />Sedimentology of Smatl Catchments by Han, Barfield and Hayes. <br />Soil Erodibility Factor "K" <br />This is a measure of the soil's susceptibility to erosion. It is dependent upon the soil's <br />resistance to detachment by rainfall and by its ability to absorb water through <br />infiltration. <br />3 <br />