Analysis for Sediment Deposition and Erosion in Key Sections of River Reach in Chongqing City during the Natural Evolution

The river reach in the center of Chongqing City lied in the fluctuant backwater of the Three Gorges Reservoir, and it was also the junction reach of the Jialing River to the Yangtze River. It’s flow conditions and sediment movement was very complex. In the Three Gorges Reservoir 175m experimental operation period, the inherent laws of flow and sediment transport of river reach was changing under reservoir regulation. Prototype measured data for 20 years was analyzed at Jiulongpo, Zhuerqi, Jinshaqi and Cuntan sections. The results show that the association with the local flow were strong for the average sedimentation intensity in Flood season and the average erosion intensity later Flood season at the four sections. Different sediment erosion and deposition intensity corresponding to the flow was presented. According to the curve of discharge and cross-section mean velocity at Cuntan hydrologic section, the cross-section mean velocity corresponding to each flow is determined. On this basis, Sediment erosion and deposition change of river reach is analyzed at Three Gorges Project 175m operation periods.