两变量洪水结构荷载重现期与联合设计值研究

Bivariate structure load return period and joint flood quantile estimation

目前常用的两变量洪水重现期所判定的危险事件和表征的水库大坝水文失事情景都存在不符合实际的情况。本文以超过坝前最高水位的频率来度量防洪安全设计标准,开展两变量洪水结构荷载重现期与最可能联合设计值计算方法研究。以清江流域隔河岩水库为例,进行应用和比较研究。实例结果表明:与结构荷载重现期相比,"OR"和"AND"重现期最可能联合设计值的设计标准分别系统偏高和偏低,Kendall和生存Kendall重现期也存在不同程度的偏低或偏高。结构荷载重现期考虑了洪峰、洪量与水库调洪规则的交互作用,符合设计洪水的实质内涵,能够达到指定的防洪标准,可为水库防洪安全设计和风险分析提供更加科学合理的依据。

Currently,flood hazard event and hydrological failure scenario judged by the widely used bivariate return period may violate the real case. In this study,the exceedance probability of the highest water level in the reservoir was adopted to measure the safety design criteria of flood control. The estimation methods for structural load return period and most likely joint design values of flood peak and volume were pre-sented. The Geheyan reservoir located at Qingjiang basin was selected as a case study to perform the application and comparative study. In this Geheyan reservoir example, it is demonstrated that compared with structural load return period,the design standards of most likely joint design values of OR and AND return period are higher or lower systematically. Meanwhile,design standards were either over-estimated or under-estimated to some extent in most likely joint design values of Kendall and survival Kendall return period. The presented structural load return period considers the interaction between flood characteristic variables,i.e. peak and volume,and operation rules of the reservoir. Consequently,it is in accordance with the essential implication of design flood and can achieve the specified flood control standards,which will provide more scientific and reasonable basis for flood control design and risk assessment of the reservoir.