三峡库区汛期洪峰和沙峰异步运动特性的三维数值模拟

三峡水库蓄水后水深的增加导致洪水传播过程中沙峰滞后于洪峰的时间增加，利用洪峰和沙峰异步运动特性进行沙峰排沙调度是减缓水库淤积的重要手段之一。采用三维数值模型SCHISM（Semi-implicit Cross-scale Hydroscience Integrated System Model）研究三峡库区洪峰和沙峰的异步运动规律，基于2013年的汛期水沙传播过程验证模型的可靠性和准确性，初步分析不同洪水位下洪峰和沙峰的异步运动特性。结果表明:数值模型能够准确地模拟三峡水库汛期洪峰和沙峰长距离的传播过程；坝前蓄水位对洪峰传播时间的影响不大，但是对沙峰传播时间的影响较为显著；坝前水位增加使水流的流速减小和挟沙能力降低，沙峰传播速度减慢且峰值沿程不断降低，最终导致库区中沙峰滞后于洪峰出现的时间沿程越来越长。研究结果可为进一步优化三峡水库的沙峰排沙调度等提供科学依据。

Three-dimensional numerical of the asynchronous movement characteristics of flood and sediment peaks in the Three Gorges Reservoir

After the impoundment of the Three Gorges Reservoir, the increase of water depth caused the increase of the lag time of the sediment peak behind the flood peak in the flood propagation. The asynchronous movement characteristics between the flood and sediment peaks can be utilized to conduct the sediment peak regulation, one of the crucial measures to reduce the reservoir sedimentation. The three-dimensional numerical model named SCHISH (Semi-implicit Cross-scale Hydroscience Integrated System Model) was adopted to study the asynchronous movement characteristics of the flood and sediment peaks in the Three Gorges Reservoir. The reliability and accuracy of the model were verified by comparing the water and sediment transport during the flood season in 2013, then the asynchronous movement characteristics of the flood and sediment peaks under different impounded levels were preliminarily analyzed based on the model results. The results showed that the numerical model could accurately simulate the long-distance propagation of the flood and sediment peaks. The impounded level in front of the dam had little influence on the propagation time of the flood peak, but had a significant effect on the propagation time of the sediment peak. The increase of the impounded level resulted in the decrease of the flow velocity and the sand-carrying capacity, so the propagation speed of the sediment peak was slower and the sediment peak value was smaller, which led to the longer lag time of the sediment peak behind the flood peak along the reservoir. The research results can provide scientific evidence for further optimization of the operation of the sediment peak regulation in the Three Gorges Reservoir.