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hydrograph and sediment graph, runoff volume, peak discharge, sediment yield, • <br />peak sediment concentration. and peak sei;tleable concentration. <br />The MUSI_E (Modified Universal Soil Loss Equation), as presented by Williams <br />(1976), is one method by which SED]:M7T II estimates sediment yields. The <br />ttUSLE method computes the sediment yield from a single precipitation event <br />with the following expression: <br />where <br />Z = g5 (Q gp)0.56 K LS CP (3-1) <br />Z = sediment yield in tons from a storm, <br />Q = the volume of runoff for the storm (acre-ft), <br />qp = the peak discharge for the storm (cfs), <br />K = soil erodibility factor, <br />LS = length slope factor, and <br />CP = control practice factor. <br />C The soil erodibility factor, K, defines the soTlrs susceptibility to erosion. . <br />The SCS has defined values of K for various soils and Wischmeier et al. (1971) <br />developed a nomograph for determining K based on the soils texture, structure, <br />and permeability. The length slope factor, LS, 1s the ratio of soil loss at <br />any length and slope relative to standard erosion plots used in erosion <br />studies. The length of the slope has been defined as the distance from the <br />point of origin of overland flow to the point that the slope decreases such <br />that deposition occurs. The control practice factor, CP, is defined as the <br />ratio of sediment loss from a field with a given .over and conservation <br />practice to that of afield in continuous fallow. Williams (1976) selected <br />the coefficient 95 and the exponent 0.56 by optimization using data on <br />watersheds in Texas and Nebraska. Methods for determining the above factors <br />and the development of the MUSLE equations are fully discussed in Barfield et <br />al. (1931). Travel time and a particle size distribution are also required to <br />route t)ie se dlment and to determine the eroded particle size distribution. <br />The eroded particle size distribution is adjusted during routing to account <br />for deposition. _ <br /> <br />