三峡变动回水区重点河段演变分析

Fluvial morphology study on key channels of the Three Gorges fluctuatingback water area

在原型观测资料的基础上,通过地理信息系统等技术手段,对三峡水库蓄水初期变动回水区重点河段的演变规律进行了分析.结果表明,三峡蓄水后这些河段均出现累积性的淤积.就空间分布而言,累积性淤积部位主要出现在弯道凹岸缓流区等处,可见水动力影响为淤积的主要原因.上游来水来沙条件与水库运行是变动回水区演变的主要影响因素.而坝前水位调整使得各河段常表现为蓄水期淤积,消落期冲刷.同时随着非汛期坝前水位的逐年抬高,累积性淤积区也随之向上游拓展.

Based on the observation data and GIS approach, this study analyzes the fluvial morphology of some key channels in the Three Gorges fluctuating back water area. Results indicate that there are accumulated depositions in all these channels after the impoundment of the Three Gorges Reservoir. The accumulated deposition mainly exists in places such as slow-velocity zone in the concave bank. Therefore the hydrodynamic factor is of the most importance in the deposition. The hydrologic conditions and the reservoir operation control the local fluvial morphology. In 2006, sediment from upstream was so scarce that all channels suffered scouring. In another aspect, these channels tended to be deposited when the reservoir stage rose, and to be scoured when the stage declined. The accumulated deposition zone kept expanding upstream along with the rising of reservoir stage in the dry season.