Ratio Producing Runoff and Sediment from More Sediment and Coarse Sediment Region Occupying Total Runoff and Sediment in the Middle Reaches of Yellow River

Based on analyzing natural environment characteristics of different producing runoff and producing sediment regions in the Yellow River basin,principles and indexes of determining more sediment and coarse sediment region have been mainly discussed and area of more sediment and coarse sediment region is calculated.It is to research coupling relations among different producing runoff and sediment regions in the Yellow River basin and runoff and sediment in the middle reaches of the Yellow River.Ratio that producing runoff volume and sediment delivery occupy total runoff and sediment in the four stations(Huaxian,Zhuangtou,Longmen and Hejin)are calculated,they are that producing annual runoff volume and sediment delivery occupy total runoff and sediment in four stations of the Yellow River 12.9% and 63.4% respectively,in which 87% of coarse sediment in the four stations comes from the more sediment and coarse sediment region.Controlling more sediment and coarse sediment region is a key for reducing sediment of four stations.It is estimated that controlling 10 000 km 2 more sediment and coarse sediment region can reduce 8% of total sediment and 10% coarse sediment respectively.