Runoff is the main factor responsible for soil erosion

so an accurate estimation of runoff is the key to predictand control soil erosion. The Soil Conservation Service curve number (SCS-CN) method is widely used for predicting directrunoff from rainfall in the area withoutobserved runoff data. Using data of 153 runoff events from 6 experimental plots with three landuse types of millet

alfalfa

and sorghum on the Loess Plateau

the applicability of SCS-CN method is validated and the parameters are optimized. Results indicate thatthe accuracy of runoff prediction by the SCS-CN method with optimizedλand CN2 values is better than thatof the standard CN method. The optimizedλvalue is 0. 01 and the CN2 values are 74

74

and 72 for millet

alfalfa

and sorghum

respectively.