Acta Geographica Sinica ›› 2021, Vol. 76 ›› Issue (1): 114-126.doi: 10.11821/dlxb202101009

• Water Cycle and Related Land Surface Processes • Previous Articles     Next Articles

Control index of sediment reduction dispatching in Chongqing reach after the storage level of TGR reaching 175 m

ZHU Lingling1(), GE Hua2, DONG Bingjiang1, YANG Chenggang1   

  1. 1. Bureau of Hydrology, Changjiang Water Resources Commission, Wuhan 430010, China
    2. Changjiang River Scientific Research Institute of Changjiang Water Resources Commission, Wuhan 430010, China
  • Received:2019-06-25 Revised:2020-11-10 Online:2021-01-25 Published:2021-03-25
  • Supported by:
    National Key R&D Program of China(2016YFC0402101);Research on the Major Sediment Problems of the Three Gorges Project(ZZ2018013001F);Scientific Research Project of China Three Gorges Group Co. Ltd(0704166)


Chongqing reach is located in the fluctuating backwater zone of the Three Gorges Reservoir (TGR). Sediment deposition and erosion of Chongqing reach is related to flood control, shipping and wharf operation. It has become one of the key problems the TGR faces. In this paper, based on the prototype observation data, the sediment scouring and silting law of Chongqing reach before and after the 175 m experimental impoundment of the TGR was investigated for the first time. In addition, combined with the analysis of river bed composition and the one-dimensional mathematical model, the scouring conditions of suspended sediment in Chongqing reach were calculated and analyzed. Furthermore, the basic conditions of sediment transport in the study reach were applied to the practice of sediment reduction of the TGR. The following conclusions can be drawn as follows: (1) From 2008 to 2012, when the water storage level of TGR reached 175 m, the erosion intensity of the river bed in Chongqing reach started to decline, and the main souring period of suspended load was postponed from the water-impoundment stage to the pre-flood stage. After 2013, Xiluodu and Xiangjiaba hydropower stations in the lower reaches of Jinsha River was completed and put into operation. The sediment of Jinsha River was intercepted and the sediment entering the Three Gorges was greatly reduced, which led to another increase of the river bed scouring intensity of Chongqing reach. (2) When the inflow in front of the Three Gorges Dam (TGD) is greater than 4000 m 3/s and the water level is lower than 167 m, the suspended load on the river bed in Chongqing reach begins to scour. When the inflow exceeds 5000 m 3/s, the water level in front of the TGD drops to 163 m, and the scouring intensity of suspended load increases obviously. Increasing the drawdown rate of water level from 163 m before the TGD to 30 cm per day can avoid the cumulative sedimentation in the Chongqing reach.

Key words: Chongqing reach, main souring period of suspended load, scouring conditions of suspended sediment, optimized operation for deposition reduction