3Liu Baoyuan, Zhang Keli, Xie Yun. An empirical soil loss equation[A]. Proceedings 12th International Soil Conservation Organization Conferenc~ Vol. m [c]. Beijing: Tsinghua Unive- rsity Press, 2002.
4Soil Conservation Service(SCS)."Section 4, hydrology".national engineering handbook [R]. U. S. Department of Agriculture, Washington, D.C. 1972: 10. 5.
