Lecture 3

Soil Erosion• Predicting soil erosion due to rainfall has been an active area of researchfor nearly 50 years. Since 1970, modeling efforts have utilized the UniversalSoil Loss Equation (USLE), and more recently the Revised Universal SoilLoss Equation (RUSLE), to evaluate soil loss caused by rainfallninoff. Both equations are defined byA = R*K*L*S*C*P• where A is the estimated annual soil loss per unit area that can be averagedover many years; R is rainfall erosivity factor that depends on intensity,quantity, and duration; K is the soil erodibility factor, which is a function ofsoil texture, organic matter content, and structure that influence stability andpermeability; L and S are topographic factors, length and steepness,respectively; C the surface-cover factor based on whether a soil isvegetated, mulched, or bare; and P is the management practice factorrelated to an erosion control application. Although the use of USLE RUSLEis generally simple, its original development and calibration consideredspecific conditions that are not truly universal. Improvements in RUSLEhave updated, expanded, and enhanced information related to each factor.