小浪底水库“腾库迎洪”期异重流形成分析

Analysis of the formation of density current in the period of discharging before flood in Xiaolangdi Reservoir

  • 摘要: 小浪底水库异重流的形成与运行规律是关系黄河调水调沙方案拟定的重要指标。基于现场调研、理论探讨与预测分析结合等手段, 明晰了2018年"腾库迎洪"期小浪底水库来水来沙过程, 根据水库调度与库区淤积形态等边界条件, 观测了异重流的形成与运行, 采用基于流速分布的水库异重流潜入点预测公式进行了计算分析。结果表明:2018年7月库区产生的剧烈冲刷, 在潜入点处发生大量淤积, 水深大幅减小, 引起潜入点下移; 潜入点位置随入库水沙增大、坝前水位降低及库区淤积的推进向坝前移动, 计算与实测结果反映了该变化过程。

     

    Abstract: The formation and creeping of the density current in the Xiaolangdi Reservoir are important indices of the water scheme and sediment regulation in the Yellow River. Previous studies have focused on the theory of density current in the Xiaolangdi Reservoir, real-time tracking on the operation process, and the analysis of surveyed data; however, they did not include related research on real-time prediction of the Xiaolangdi Reservoir and the tracking analysis of latest theoretical results. In this study, a field investigation, theoretical analysis, and prediction analysis were conducted to explain the process of water and sediment inflow from the Xiaolangdi Reservoir, during the period of discharging before the flood in 2018. The formation and creeping of the density flow were observed according to boundary conditions such as reservoir operation and reservoir siltation morphology. The plunging point formula of the density flow in the reservoir was predetermined, based on the velocity distribution. The results show that, in July 2018, intense scouring in the reservoir caused a significant amount of siltation to fall at the plunging area, thereby considerable decreasing the depth of clear water. This caused the plunging point to move downstream. The position of the plunging point moved ahead of the dam with the increase in water and sediment inputs, decrease of water level before the dam, and advance of the siltation in the reservoir. The calculated and measured results reflect on the changing process. These results can be used as a reference for the preparation and post-evaluation of reservoir water and a regulation plan for sediments. The results can also provide technical support for the operation as well as planning and design of reservoirs in sediment-laden rivers.

     

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