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~~ <br />7 <br /> r~nc~-r <br /> 'Ihe Universal Soil Lass Equation, USLE provides a means of: (1) evaluatirg <br /> the current status of soil erosion aryl (2) monitoring degradation or improvement <br /> over time. 4t~e USIE is an erosion model which estimates longterm average annual <br />r soil loss from sheet and rill erosion based on currem site conditions. <br /> Estimated soil lass (A) 15 ocagrrted aS the product of factors r,a p.,aea„r; *~ the <br /> relative contributions of local rainfall patterns (R), soil er odibility (K), <br /> slope length and steepne ss (LS) , rock and vegetation groiad Dover and vegetation <br /> canopy cover (C), and supportive conservation practioPS (P). 'lire soil loss <br />r equation is: <br /> A= R x K x LS x C x P <br /> ~ <br /> where A is generally P ~*~ <br />in tons per acre per year, all oth er factors are <br /> unitless. <br />Rainfall Factor (R <br />Zhe rainfall factor (R) is the rnm~ber of EI30 units (erosion index units) or <br />the erosive energy of the storm rainfall. It is the product of the total kinetic <br />energy (E) of a storm and the ~++~Y~~~ 30 minute intensity of the storm divided by <br />100, or EI30/100. <br />Zt1e total kinetic energy of the storm is usually determined by dividirg the <br />storm into intensity classes (i.e. 0-1 irx3~/hour, 2-3 inch hour, etc.), <br />e determining the total rainfall amount in each class and determining the energyr <br />present. 'IIus type of information may also be obtained Eton calculating <br />precipitation depth duration frequency (L~F) cloves. <br />'The rainfall factor *+ep*x+~P*+*G the effects of raisdxvp impact on the soil <br />for the entire duration of a storm (wisclmieier aryl Smith, 1978). If R values are <br />