重庆主城区河段是西南地区水陆交通枢纽,其河道泥沙冲淤关系到防洪、航运及码头作业等一系列问题,是三峡水库泥沙问题的重点内容之一。三峡水库175 m试验性蓄水后,该河段位于库尾段,年内水力特性显著改变,河床冲淤规律相应发生变化。依据实测水沙及河道原型观测资料,对比研究了近15 a天然状态下和三峡水库175 m水位试验性蓄水后河段的泥沙冲淤变化。结果表明:自然状态下重庆主城区河段以冲刷为主,汛后走沙、汛期淤积规律明显,且汛后为主走沙期;三峡水库175 m水位试验性蓄水后至2012年河床冲刷强度下降,主走沙期推迟至汛前消落期;2013年以来上游来沙大幅减少使得河段冲刷强度增大。研究成果可为三峡水库优化调度和重庆主城区河段的规划治理提供参考。

Chongqing reach is well known as the land and water transport hub in southeast China. Sediment erosion and deposition in Chongqing reach, as related to flood control, navigation and dock operation, is a core issue in the demonstration phase of Three Gorges Reservoir (TGR). Since the water level in front of Three Gorges Dam reached 175 m, the hydraulic characteristics and sediment erosion and deposition in Chongqing reach, as the tail area of the TGR, has changed prominently. According to prototype observation data, the sediment scour and silting in Chonqing reach from 2003 to 2016 when the water level in front of Three Gorges Dam increased from 145 m to 175 m was compared and analyzed. Results showed that in natural condition, sediment erosion dominated the Chongqing reach, with sediment always silting in flood season and scouring after flood season. From 2009 to 2012, the intensity of river bed scour in Chongqing reach decreased, and the erosion period delayed to seasons before flood of the next year. As sediment yield greatly declined after the operation of cascade hydropower stations in the lower Jinsha River, scour is very likely to occur again in Chongqing reach. The research results are expected to provide reference for the operation of TGR and the planning and regulation of Chongqing reach