5Gutman G G.Vegetation indices from AVHRR:An update and future prospects[J].Remote Sensing of Environment,1991,35(2-3):121-136.
6Wischmeier W H,Johnson C B,Cross V.A soil erodibility nomograph for farmland and construction sites[J].Journal of Soil and Water Conservation,1971,26(5):189 -193.
7Williams J R,Renard K C,Dyke P T.EPIC:A new method for assessing erosion's effect on soil productivity[J].Journal of Soil and Water Conservation,1983,38(5):381-383.
