三峡水库泥沙淤积滞后响应规律

滞后性是河流系统自动调整的重要特征之一，以往对于三峡水库泥沙淤积滞后响应规律的研究相对较少。本文采用实测资料分析与滞后响应模型等理论模型研究相结合的方法研究三峡水库泥沙淤积响应规律。首先，统计三峡水库蓄水以来水沙条件以及泥沙淤积特性变化，分析梯级水库蓄水对三峡水库水沙条件以及库区泥沙淤积的影响，在此基础之上，通过考虑入库流量、含沙量、泥沙中数粒径以及坝前水位优化已有的库区泥沙淤积滞后响应模型。从已有的以及优化后的模型模拟结果可以看出：①优化后的泥沙淤积滞后响应模型能够更好得模拟梯级水库蓄水后三峡水库泥沙淤积的过程。②梯级水库蓄水后，三峡水库来水来沙变幅减小，来沙更加集中在汛期，河道调整速率加剧，河道调整的时间尺度有所缩短，表现为三峡水库泥沙淤积滞后响应年限从前期4年缩短到前期3年。③梯级水库蓄水后，入库含沙量对于库区泥沙淤积过程的影响权重有所增加，入库流量以及坝前水位对库区泥沙淤积过程的影响权重降低。

Delayed Response Law of Sedimentation in the Three Gorges Reservoir

Hysteresis is one of the important characteristics of automatic adjustment of river system, while there are few studies on the law of sediment delayed response in the Three Gorges Reservoir (TGR). Based on the delayed response model, the measured data were analyzed and the delayed response model was modified by considering the sediment concentration and sediment particle size in order to construct the delayed response model in accordance with the characteristic of sediment deposition in TGR. Firstly, the changes of water and sediment conditions and sediment deposition characteristics since the impoundment of TGR were counted, and the influence of cascade reservoirs in the upper Yangtze River was analyzed. In order to simulate and analyze the sedimentation delayed response law in different periods of TGR, the existing model was used and modified. Based on the existing and modified response model simulation results, it can be seen that: 1) The modified response model can better simulate the sediment deposition process of TGR after the impoundment of cascade reservoirs because of the consideration of sediment concentration and sediment particle size. 2) After the impoundment of cascade reservoirs, the fluctuation range of inflow and sediment decreases, the sediment inflow of TGR is more concentrated in flood season, both of which make the channel adjustment rate increase, the delayed response time of sediment deposition in TGR is shortened from the early 4 years to the early 3 years. 3) After the impoundment of cascade reservoirs, the influence weight of sediment concentration on the sediment deposition process increases, while the influence weight of flow and water level in front of dam decreases. By using the modified model, it can be seen that the inflow of sediment concentrates more in the flood season, which make the delayed response time of sedimentation in TGR shorten, and the influence weight of sediment on the sediment deposition increases.