基于防洪重现期的水库安全设计研究

Reservoir Safety Design Based on Flood Control Return Periods

在进行水库防洪安全设计时,现阶段水库的防洪安全设计大多以单一变量来控制,忽略了变量间的相关性,无法全面反映洪水事件的真实特性。采用二维Copula函数构造年最大洪水峰、量的联合分布,以两变量重现期为防洪标准,选取多组峰、量组合,用以放大典型洪水过程线,经水库调洪演算得到一系列设计水位,最终得到这一系列设计水位的变化范围。为研究不同设计重现期对水库设计值的影响,采用防洪重现期,在水库安全设计方面展开研究,并与当前较常用的四种传统重现期(联合重现期、同现重现期、Kendall重现期以及生存Kendall重现期)进行对比分析,以位于柳江流域都柳江河段的洋溪水库为例,计算分析五种重现期标准下的设计水位,探讨防洪重现期在水库安全设计中的合理性、可靠性及优势所在。研究表明,任何重现期水平下的防洪重现期危险域确定且唯一;防洪重现期等值线的形状与工程的行洪界面存在耦合关系;不同重现期标准下的设计水位差别较大,且基本满足联合重现期>防洪重现期>Kendall重现期>生存Kendall重现期>同现重现期的规律;水库防洪安全设计中,防洪重现期标准下的防洪设计参数所对应的防洪能力与工程防洪标准一一对应,可在缩减工程成本的同时,有效抵御洪水风险,保证工程安全。

The existing reservoir flood control safety design is largely governed by a single variable,disregarding the correlation between factors and failing to accurately reflect the true nature of flood events.In this study,the combined distribution of the annual maximum flood peak and volume is constructed by using the two-dimensional Copula function.To magnify the typical flood hydrograph,various groups of peak and volume combinations were chosen using the two variable return period as the flood control standard.The reservoir flood routing was used to obtain a series of design water levels,and it is this series’variation range that is then determined.In order to research how various design return times affect the reservoir’s design value,this paper studies the reservoir safety design based on flood control return periods.Four traditional return periods(Joint return period,concurrent return period,Kendall return period and survival Kendall return period)commonly used at present are compared and analyzed.Taking Yangxi Reservoir located in Duliujiang reach of Liujiang River basin as an example,this paper calculates design water level of the five return period standards,and discusses the rationality,reliability,and advantages of flood control return period in reservoir flood control safety design.The results show that the risk region of flood control return period at any return period level is definite and unique.There is a coupling relationship between the contour shape of flood control return period and flood discharge interface.The design water levels under different return period standards vary greatly,and basically meet the rule of T_(OR)>T_(F)>T_(KD)>T_(SK)>T_(AND).The flood control capacity corresponding to the flood control design parameters under the flood control return period corresponds to the project flood control standard,which can reduce the project cost,effectively resist the flood risk,and ensure the safety of the project.