关键词: 水库泥沙, 卵石推移质, 起动公式, 走沙条件, 三峡水库调度, 重庆主城区河段

Abstract: The characteristics of river erosion and siltation have changed significantly in the Chongqing reach of the Yangtze River after the 175 m experimental operation of the Three Gorges Reservoir. Studying the sediment transport law in the Chongqing reach and establishing the relationship between sediment transport and the Three Gorges Reservoir regulation have great significance for reservoir regulation optimization and deposition reduction in the reservoir. Therefore, the transport and starting-conditions of pebble bed load in the Chongqing reach of the Yangtze River were analyzed in this study. Also, the long-series measured data of pebble bed load at Cuntan station, the two-dimensional mathematical model and formula of pebble bed load incipient motion were used in this study. The results showed that since 175 m experimental operation of the Three Gorges Reservoir, the transfer load of pebbles had significantly reduced, the pebble grains had been refined and the transport-time had also been shortened greatly in reach of Chongqing urban. Furthermore, the critical conditions of pebble bed load incipient motion were that the water level in front of the dam was less than 157 m, and the upstream flow was greater than 6800 m3/s, which was verified by measured data in 2016. It was also found that Three Gorges Reservoir regulation could increase the pebble-bed-load transport and alleviate sedimentation in the Chongqing reach.

Key words: reservoir sediment, pebble bed load, formula of sediment incipient motion, transport and starting-conditions of sediment, Three Gorges Reservoir regulation, Chongqing reach of the Yangtze River