Flow-sediment features of Three Gorges reservoir since impoundment

Since impoundment of Three Gorges reservoir on June 1,2003,TGP began to play comprehensive benefit in flood control,power generation,navigation etc.According to hydrologic and sediment observation data,the flow and sediment features flowing into and out of Three Gorges reservoir are analyzed systematically.The analysis results demonstrate that comparing with that before 1990,the water volume in upstream of the Yangtze river had less variation during the period of 1991-2005,but sediment yield decreased obviously.The annual sediment yield at Cuntan hydrologic station on the Yangtze river and Beipei station on the Jialing river decreased about 32% and 75% respectively.Comparing with mean annual amount,the sediment into Three Gorges reservoir during the period 2003-2005 decreased by 43%～63%,the sedimentation in Three Gorges reservoir was 377 million t,sediment discharge ratio is 40%.Influenced by sediment retaining of Three Gorges reservoir,the sediment yield in the dam downstream decreased largely,sediment content became smaller obviously and granular size of suspended sediment became more coarser.