多沙河流水库调度与河道响应的耦合计算：以小浪底水库为例

Channel response to reservoir operation in sediment-laden rivers is an important index for efficacy evaluation of reservoirs. By using empirical and experimental methods, traditional research focused on computing the effects of a certain amount of river operation plans on channel adjustments and selecting the best one, which was neither optimized in the whole flow solution space, nor dynamically optimized with channel adjustments in real time. Therefore, by using theoretical analysis and numerical model, this project proposed a quantitative method to pick up those bankfull characteristic values in multiple-channel reaches, adopted the hydrodynamic conservation conditions and morphological evolution law from a non-equilibrium state to an equilibrium state, developed a conceptual model of channel response in a middle time scale, set up a long-term numerical procedure for reservoir optimal operation with multiple objectives, organized the coupling computation between reservoir regulation and channel response and realized dynamic optimization of flow regulation of the Xiaolangdi Reservoir. The research result will be helpful for deepening the understanding of fluvial processes below a dam construction, and provide a decision-making reference for reservoir regulation in sediment-laden rivers, which are important in scientific and engineering field.

多沙河流水库调度对其下游河道的影响，是评价水库功能的重要指标。传统研究聚焦于使用经验和试验方法求解若干水沙方案对下游河道的作用效果并进行比选，没有实现全解空间内水库调度随河道响应结果的动态优化。因此，本项目拟采用理论研究和数学模型相结合的手段，提出多流路条件下河道响应平滩特征值的客观量化方法；应用水动力学的守恒条件和地貌学非平衡态向平衡态的演进规律，开发中时间尺度河道响应的概念化模型；集成建立小浪底水库长时段多目标优化调度计算方案，实现水库调度与河道响应之间的耦合计算与动态优化。研究成果将有助于深化对坝下游河床演变的认识，同时也为多沙河流水库的优化调度提供了决策参考，具有重要的科学与工程价值。

多沙河流水库的修建与运行深刻影响下游的河床演变过程，而下游河道整治目标又对水库运行提出明确要求，二者的耦合计算是当前水库精细化调度的现实需求。本文以黄河小浪底水库为例，构建了兼顾下游河道整治需求与水库综合效益的多沙河流水库多目标优化调度的数学模型，集成了水库排沙、库区淤积、水库发电、下游河床演变等多个计算模块，其中，下游河床演变模块是整个数学模型的核心，其计算结果不仅作为当年的关键约束条件，也将作为第二年新的初始条件代入计算。.将该模型应用于2009年小浪底水库优化调度方案计算，给出了不同调度目标下的优化调度结果。结果表明，发电量最大方案相比真实调度方案，其发电量增加20.7%，排沙比为4.9%；而综合效益最大方案相比真实调度方案，其发电量增加10%，排沙比增至79%。在两种方案下，下游河道均能维持4000m3/s左右的中水河槽，均优于真实的调度方案。因此，现有的常规调度方案仍有进一步提升的潜力；利用好多沙河流水库大流量排沙过程，在下游河道维持中水河槽的前提下适当排沙出库，延长水库的使用寿命，是提升多沙河流水库长远综合效益的一种可能途径。