Effect of Retaining Coarse Sediment on Sedimentation Reduction in the Lower Yellow River

The regulation mechanism of coarse and fine sediment in Sanmenxia confluence region and in the lower Yellow River is studied as the key issue on the basis of recorded data and combining with mathematical model. The analysis and calculation show that detention of coarse sediment will result in the ratio of 0.5 to the sedimentation reduction respectively for the confluence region and the lower Yellow River, therefore, the main effect of sedimentation reduction is in the lower Yellow River. If coarse sediment concentration of entering to the lower Yellow River had been controlled between 15?% to 20?% from 1974 to 1990, there would have been the ration of sedimentation reduction of 0.65 to 0.80 and with mainly decreased coarse sediment in the lower Yellow River.