考虑水库调蓄影响的设计洪水计算方法

Design Flood Estimation at Downstream Section by Considering the Impact of Upstream Reservoir Regulation

摘要: 水库的调蓄作用，改变了其下游天然洪水的水文情势，直接影响下游断面的设计洪水。以清江流域梯级水库为例，通过基于Copula函数的条件期望和最可能地区组成，结合规范采用的同频率地区组成方法，拟定了五种水布垭水库和区间流域洪水组合方案，推求受水布垭水库调蓄影响的隔河岩断面设计洪水。计算结果表明：与天然情况相比，考虑水布垭水库调蓄的不同重现期隔河岩断面设计洪水均减小。削减最大的是条件期望组合Ⅰ方案，最小的是条件期望组合Ⅱ方案。规范采用的同频率方法有一定的代表性，但它既不是最可能发生的，也不是对隔河岩断面防洪最不利的情形。研究成果可以供清江梯级水库防洪调度与运行管理参考，同时为水库下游断面设计洪水计算提供了一条新思路。

Abstract: The hydrological regime of the natural flood has been changed because of the reservoir storage and regulation, which directly impact on design flood in the downstream section. The Shuibuya-Geheyan cascade reservoirs in the Qingjiang basin were chosen as the case study. Five schemes based on the conditional expectation, most likely composition and same frequency methods were used to analyse flood regional combination of the Shuibuya reservoir and interval basins. The design floods of the Geheyan section were estimated by considering the impact of the Shuibuya reservoir regulation and compared with that of natural condition. The results show that design peak discharges of five schemes are reduced; the maximum and minimum values are estimated by the conditional expectation I and the conditional expectation II schemes respectively. The same frequency methods are neither the most likely to occur, nor the most unfavorable circumstances for flood control of Geheyan section. This study not only can provide references for the Qingjiang cascade reservoirs operation and management, but also provide a new way for design flood estimation at reservoir downstream section.