Analysis of water and sediment changes in Upper Yellow River

Based on the measured data of Toudaoguai hydrological station,the water and sediment changes are analyzed through the yearly runoff and sediment changes,distributions within a year,and the characteristics of floods and so on.The result shows the turning points of the changes were the years when the Liujiaxia reservoir and Longyangxia reservoir were put into operation respectively.The decrease of natural runoff and the increase of water consumption are the direct reasons for the decrease of incoming runoff in the upper Yellow River.The runoff is reallocated by the regulation of the Liujiaxia and Longyangxia reservoirs.Flattening the flood peak and regulating the water discharge cause the remarkable decline in the flood peak and homogenization of the flow in the downstream of the reservoirs,which has obvious negative effect on sediment transport.To learn the reasons of the water and sediment changes and the negative effect caused by them can provide reference for the appropriate water resources exploitation and the comprehensive treatment to the Ningmeng reach of the Upper Yellow River.