Analysis of sediment scouring and silting in Chongqing reach
Sediment movement in Chongqing reach is a main problem, which is widely noted by engineers, in particular after the 175m experimental water-impoundment of Three Gorges Reservoir (TGR). The paper compares the flow characteristics and sediment movement before and after the 175m experimental water-impoundment of Three Georges Reservoir from February 1980 to December 2013, based on hydrographic and bathymetric data. It turns out that before the 175m experimental water-impoundment of TGR, water surface slope in Yangtze River is influenced mainly by river configuration and interactions between Jialing river and Yangtze River, when Chongqing reach was in in its natural state and had 13.282 million m3 of sediment erosion quantity. Since September 2008, the influence of water level in front of dam and speed of water level falling prevail. The change of sediment scouring and deposition in Chongqing reach were affected by TGR operation, which varied with different operating periods of TGR and it is estimated that Chongqing reach produce 8.747 million m3 of sediment erosion quantity. Finally, the paper comes to a conclusion that the sediment movement in Chongqing reach is affected by the comprehensive effect of incoming water and sediment, the operation of TGR, the interactions between Jialing river and Yangtze River, the backwater of Tongluoxia and so on, and is very complex.
