Water and soil conservation measures of slope influence mainly sediment in the region of the middle reaches andthe upper reaches of Weihe watershed,but the measures of water conservancy such as reservoirs,dams and irrigation projeets and so on,have an effect on sediment in the downreaches area,Agricultural irrigation affects primarilyrunoff.hydrology and sediment data of the watershed have been analysed statisticaly,the result shows:in 1970’sthe runoff amount which has been decreased by rainfall and watershed control is 22.6%and 77.4%respectively inthe watershed.The seditment amount which has been decreased bv rainfall and watershed control is 47.0%and53.0%respectively.But in 1980’9,the latter are respectively 21.3%and 78.7%,the latter are respectively13.4%and 86.6%.