变化环境下双牌水库设计洪水过程分析

Analysis of Design Flood Process in the Shuangpai Reservoir Considering Changing Environment

摘要: 水库自身防洪安全是保障流域水安全的最重要环节之一，但过去半个世纪外部环境的不断变化给大坝防洪安全带来了更严峻的挑战。本文以潇水流域下游大型水库“双牌水库”为典型案例，评估了变化环境下相同标准设计洪水对大坝防洪安全的影响。首先，根据统计学方法验证了历史期洪水序列仍服从一致性假定，并采用皮尔逊III型分布对洪水序列进行拟合，百年一遇设计洪水与早年估计结果仅下降了约5%左右，进一步采用同频率法确定设计洪水过程线；其次，通过实地测量获取了库区地形数据，对比分析了库区泥沙淤积对库容的影响；根据最后的调洪计算结果，同一标准设计洪水将库区设计洪水位上升0.95 m，而库区淤积是最直接的影响因素。结果表明，变化环境下不仅要考虑非一致性极值统计方法，也应重视库区环境变化所带来的潜在影响。

Abstract: Reservoir flood control is one of the most important measures to ensure the water safety of the river basin. However, the continuous change in the external environment has brought more serious challenges to flood control during past half-century. The Shuangpai Reservoir, a large reservoir in the lower reaches of the Xiaoshui River basin, is selected as case study. This paper evaluated the impact of design flood (under the same standard) on reservoir safety in the changing environment. Firstly, it is verified that the historical flood series is still stationary based on the statistical tests. The Pearson type III distribution is adopted to fit the samples. Compared with the previous result, the estimated 100-year return level only is decreased by about 5%, and the design flood hydrograph is determined by the peak and volume amplitude method. Secondly, we analyzed the influence of sediment deposition on the reservoir capacity by measuring the surface and underwater topography in the reservoir area. Finally, the design flood level (100-year return period) would have an increase of 0.95 m based on the reservoir routing, suggesting that the accumulation of sediment is the most direct influencing factor. The results indicated that although nonstationary statistical theories should be considered in the changing environment, the potential impact of environmental change in the reservoir area is of great significance.