Runoff and Sediment Reduction Effects through Hydraulic and Soil-water Conservation Measures in the Middle Yellow River and Its Influence on the Lower Yellow River

Based on the actual measured runoff and sediment records, the reasons for changes of runoff and sediment in the middle Yellow River in recent years and its influence on the lower channel are analyzed and studied in the paper. The results demonstrated that runoff and sediment into the Yellow River has been reduced greatly in recent years by the effects of both climate and hydraulic and water and soil conservation measures. Runoff reduction has made finer sediment silt increase, more severe of flow cut-off in the Lower Yellow River channel, though sediment reduction has made decrease of silt in the channel of the Lower Yellow River. It is pointed out furthermore that it is possible to alleviate the problems of flow cut-off and high water level at normal floods in the Lower reach, only if the treatments in the coarse and overburden sediment area are speeded up, and water saving measures are carried out in the Lower Yellow River and the area of clear water and lower sediment content.