Research Of The Changing Process And Regulation On The Upstream And Downstream Waterway Of TGP Before And After Reservoir Impounding

The water and sediment have been changed since the TGP dam began impounding. Sediment silted up in reservoir because the water flow velocity became smaller and the sediment carrying capacity lowered. The accumulation trend of deposition appeared at the silting reach of the variable backwater zone. And at the downstream of the dam, the river channel has been eroded as its elevation has been reduced because of the suspended-sediment concentration was very small. At some river reaches the water depth was too low, the water slope was too steep and the water velocity was too big to navy.Compared the prototype observation hydrology and sediment data of waterway after the TGP reservoir began to run with the data before the reservoir ran, this paper systemly analyzed and studied the water way of the TGP reservoir and the downstream of Gezhouba project. And furthermore, this paper also paid more attention to study the silt deposition and erosion of the silt river reaches at the end of reservoir and critical shoal areas at the downstream of the dam. Also, this paper made the first study on the variation of backwater zones at the end of reservoir, and the approximate boundary of the end of backwater under different water level and discharge was given by comprehensive research in recent decade years.This research will be important to fatherly study the reservoir storage program and operation schedule in the different stage, and promote the comprehensive benefit of TGP on the level of greatest limit. At the same time it will make the beneficial foundation research to manage the water way systematically and to guarantee the navigation smoothly of Yangtze River.