1.College of Environmental Sciences and Engineering,Peking University,100871, Beijing;2.Research Institute of Forestry,Chinese Academy of Forestry,Key Laboratory of Tree Breeding and Cultivation,State Forestry Administration,100091,Beijing;3.Institute of Geographic Sciences and Natural Resources Research,CAS,100101,Beijing;4.Hunan Academy of Forestry,410004,Changsha;5.Forestry Bureau of Cili County,415300,Zhangjiajie,Hunan:China
Abstract：Taking Nverzhai small watershed in Wuling Mountain area as study area,the characteristics of runoff and sediment yield events based on 77 typical observed rainfall events in 2004—2008 were studied.The results showed that the rainfall amounts of 77 events were mainly between 25.0-49.9 mm and 50.0-100.0 mm,which held 67.53% in total rainfall.Rainfall intensity were mainly between 10-40 mm/h.Sediment yield of watershed mainly depends on several large rainstorms.Rainfall in flood season would determine the amount of runoff and sediment yield of watershed.It was showed that there was a comparatively obvious linear relationship between rainfall and runoff depth and sediment yield.Rainfall,runoff depth and rainfall erosivity had significant effects on sediment yield.Fitted linear regression equation of runoff depth and sediment yield were optimal,its regression coefficient were 0.684 7.Based on correlation
analysis of 12 indexes about rainfall,runoff and sediment,multiple stepwise regression analysis about four main indexes of runoff depth,flood peak,sediment yield,rainfall erosivity were completed.The value of R2 of regression equation were all bigger than 0.85 and passed significance test.This showed that the fitted effect of regression equation were better.This equation can be used to calculate relevant indexes.This results can be used for monitoring and forecasting of soil and water loss as well as plan of soil and water conservation.
2011, Vol. 9 
