基于非对称乘积Copula函数的城市雨洪遭遇风险分析

Risk analysis of urban rain-flood encounter based on asymmetric product Copula function

针对沿江城市暴雨与外江洪水诱发的内涝问题,对城市雨洪遭遇特性开展研究。以广东省肇庆市端州区为例,利用长系列实测降水量和西江流量数据,分别采用对称和非对称乘积Copula函数构建雨洪联合分布,采用赤池信息准则和图形评价法选择最优Copula函数进行雨洪遭遇风险分析。结果表明:非对称乘积Frank CopulaⅡ函数拟合效果最优;以暴雨为主的组合中,端州区发生较大量级暴雨时,西江发生洪水的条件风险概率相对较高;以洪水为主的组合中,不同洪水重现期雨洪联合风险概率均略大于相应西江洪水出现频率。

Aiming at the urban waterlogging problem induced by urban rainstorm and outer river flood,the characteristics of urban rain-flood encounter were studied.Taking Duanzhou District of Zhaoqing City,Guangdong Province as an example,rain-flood joint distributions were constructed with symmetric and asymmetric product Copula functions,respectively,based on long series of measured rainfall data and Xijiang River streamflow data.The optimal Copula function was selected by Akaike information criterion and the graph evaluation method for rain-flood encounter risk analysis.The results show that the asymmetric product Frank Copula II function has the best fitting effect.In the rainstorm-dominated combination,the conditional risk probability of Xijiang River flood is relatively high when heavy rain occurs in Duanzhou District.In the flood-dominated combination,the rain-flood combined risk probability under different flood recurrence periods is slightly greater than the corresponding frequency of Xijiang River flood.