变化环境下洪峰-洪量组合设计值计算方法研究

针对平稳性条件下洪峰-洪量组合设计值计算方法不适用于变化环境下非平稳性情形这一难题，基于时变Copula函数，构建了可综合考虑洪峰-洪量边缘分布非平稳性和变量间相关结构非平稳性的时变动态Copula多维联合分布模型，分析了洪峰-洪量联合分布规律随时间的非平稳性演变特征；基于等可靠度法和条件期望组合法，提出了变化环境下非平稳性洪峰-洪量组合设计值计算方法，实现了变化环境下指定重现期对应洪峰-洪量期望组合设计值的推求。以黄龙滩站洪峰和年最大7d洪量系列为例进行了实例分析，结果表明，洪峰-洪量联合分布规律随时间变化显著，指定重现期对应洪峰-洪量设计值的期望组合受工程使用年限影响，随使用年限的增加呈减小趋势。

Calculation method of design value combination of flood peak and flood volume under changing environment

To address the problem that the calculation method of the design value combination of flood peak and flood volume under stationary conditions cannot be applied for the non-stationary case under changing environment, this paper firstly constructs the multi-dimensional joint distribution model with time-varying dynamic Copula function, which can comprehensively consider the non-stationarities of marginal distributions and correlation structure between variables of the flood peak and flood volume. Then the nonstationary evolution characteristics of the joint distribution of flood peak and flood volume over time are analyzed. Subsequently, based on the equivalent reliability method and the conditional expectation combination method, the calculation method of design value combination of the flood peak and flood volume under changing environment is proposed, which can be applied to estimate the expected design value of flood peak and flood volume combination with a given return period under the changing environment. Taking the flood peak and maximum 7-day flood volume series at the Huanglongtan Station as examples, a case study is conducted. The results show that the joint distribution characteristics of flood peak and flood volume changes significantly with time, and the expected combination design value of flood peak and flood volume corresponding to the specified return period is affected by engineering design lifetime with a decreasing trend as the design lifetime increases.