变化环境下的水文频率分析及成果不确定性评估方法研究

The impact of climate change and anthropogenic activities has changed the stationary characteristics of the hydrological extreme series, thus posing a challenge on the stationary hydrological frequency analysis method which relies on the assumption that the series should be stationary. On the basis of our previous research, this application further studies the concept of Equal Reliability (ER) for the estimation of design value under non-stationary conditions. The main research contents are as follows: ① Based on the generalized additive model and Bayesian theory, the time-varying parameter probability distribution model describing the non-stationary statistical characteristic of the variables is constructed, and the ER is developed to estimate the design flood for a project to be constructed and to adjust the original design flood for an already constructed project. ②The ER is extended to multivariate non-stationary hydrological frequency analysis. Based on the copula theory, the multivariate dynamic copula joint distribution function is constructed to describe the non-stationary statistical characteristic of the marginal distribution and dependent structure, and the ER and conditional most-likely-combination method is proposed to estimate the design value in multivariate case. ③ The uncertainty assessment on the design value provided by the non-stationary hydrological frequency analysis is conducted, and the quantitative evaluation method for hydrological design reliability is proposed. The research results will form innovation in the theory and method of non-stationary hydrological frequency analysis in changing environment.

气候变化及人类活动的影响改变了水文极值系列的一致性特征，给现行基于一致性假定的水文频率分析方法带来挑战，亟需发展变化环境下非一致性水文频率分析理论与方法。本申请在前期研究基础上，进一步深入研究基于等可靠度概念的非一致性条件下设计值估计理论与方法。重点研究内容包括：①基于广义加法模型与贝叶斯理论，构建描述非一致性变量统计分布特征的变参数概率分布模型，解决等可靠度概念在待建工程设计洪水计算和已建工程设计洪水调整方面的应用难题。②将等可靠度概念拓展到多变量的非一致性水文频率分析。基于Copula理论，构建可综合考虑边缘分布非一致性和变量间相依结构非一致性的动态Copula联合分布函数模型，提出基于等可靠度概念和条件最可能组合关系的多变量水文设计值计算方法。③研究非一致性水文频率计算成果的不确定性问题,提出水文设计值可靠性的定量评估方法。研究成果将在变化环境下水文频率分析计算理论与方法层面形成创。

气候变化及人类活动的影响改变了水文极值系列的一致性特征，给现行基于一致性假定的水文频率分析方法带来挑战，亟需发展变化环境下非一致性水文频率分析的理论与方法。本项目围绕水文极值系列变异性诊断、变参数概率分布模型构建、非一致性条件下洪水设计值计算及成果不确定性分析开展了变化环境下水文频率分析及成果不确定性评估方法研究。①研究了非一致性条件下水文极值系列的趋势性/跳跃性诊断方法，尤其是针对单变量跳跃点诊断方法只能识别跳跃点位置，而无法判定系列中何种参数发生变化，提出了差异性度量指标法诊断系列中何种统计参数（均值、方差等）发生变异。②基于广义加法模型与贝叶斯理论，构建了描述非一致性条件下水文极值变量统计分布特征的变参数概率分布模型，用以描述水文极值分布特征随时间演变规律；③改进了用于变化环境下非一致性洪水设计值计算的等可靠度方法，使其可应用于变化环境下已建工程洪水设计值的复核调整；④构建了可综合考虑洪峰-洪量边缘分布非一致性和变量间相依结构非一致性的二维联合分布模型，提出了基于等可靠度方法和条件期望组合关系的洪峰-洪量组合设计值计算方法，拓宽了等可靠度方法的应用范围；⑤ 研究了变参数概率分布模型中参数估计不确定性、驱动参数变化的协变量不确定性以及两类不确定性耦合对洪水设计值的影响，提出了洪水设计值不确定性的定量评估方法。研究成果在变化环境下水文频率分析计算理论与方法层面形成创新。

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