梯级累积作用下水库泥沙过程多尺度响应机制研究

The sediment problem in cascade reservoirs at the river basins in China is a hot spot issue which concerned with the safety of water resource and energy. For the reason of accumulative effect under the condition of cascade reservoirs, there are not only the runoff process and its frequency, but also recovery process of sediment concentration and grain size changed largely than that in the condition of single reservoir, which would cause the change of the rules of sediment sorting and deposition along the longitudinal profile, and in turn, the slope of profile is also changed. The change of profile slope and the process of sediment sorting and deposition are the macroscopic and microcosmic forms of the sediment process in the reservoir, which also are the key points in the study of the sediment response mechanism under the condition of cascade reservoirs. In this study, based on the quantitative distinguish of different influence factors and accumulative effects, the response mechanism of sediment process under the condition of cascade reservoirs is studied from the aspects of the profile slope and sediment sorting and deposition by generalized experiments. The anticipated results can not only refer to sediment control, optimal operation and multipurpose use of the cascade reservoirs, but also refer to drainage basin planning in China.

随着我国各大流域梯级水库建成运用，梯级水库的泥沙问题已成为制约地区水安全的重要技术问题之一。由于梯级自上而下的累积作用，来水来沙过程变异明显，与调度方式变化相互交织，使得梯级运行环境中的水库泥沙过程响应明显不同于单库情况。纵剖面形态变化和不同颗粒泥沙分选是水库泥沙过程的宏观和微观表现，也是梯级累积作用下的水库泥沙过程多尺度响应的关键核心。本项研究拟在对梯级水库水沙变异特征识别及梯级累积作用表征的基础上，主要通过室内概化模型试验，从宏观和微观不同尺度揭示水库泥沙过程对梯级累积作用的响应机制。项目预期成果不仅可为梯级水库运行控制和综合效益发挥奠定基础，还能为我国流域规划开发提供参考，具有较为广阔的应用前景。

随着我国各大流域梯级水库建成运用，梯级水库的泥沙问题已成为制约水库优化调度及地区水安全的重要技术问题之一。本项目在国内外已有研究成果基础上，通过原型资料分析、数学模型计算以及概化试验等手段，以溪洛渡、向家坝、三峡水库梯级运用为背景，重点针对三峡水库库区泥沙淤积过程、纵剖面变化及其泥沙分选规律开展研究，分析了梯级累积作用下的水沙变异特征，对三峡水库水沙变化、坝前水位运用方式等因素对库区泥沙过程的影响及其指标进行了研究；揭示了三峡库区泥沙淤积过程、纵剖面变化及泥沙分选的规律，从河段尺度及库区尺度上揭示了泥沙淤积机理，基于挟沙力指标讨论了三峡库区纵向淤积分布形成机理；探讨了库区细颗粒泥沙的絮凝沉降特性，建立了山区河道一维水沙数学模型，预测了梯级作用下三峡库区的淤积过程。从来水来沙变化及坝前水位变化两方面，详细探讨了三峡库区淤积过程、纵剖面变化及平衡状态，揭示了三峡水库泥沙过程多尺度响应机制。项目成果可以三峡水库等类似水库的优化调度提供参考。