涝灾的发生往往是多种水文致灾因子共同作用的结果，而传统的排涝标准以超过某一量级暴雨的重现期作为排涝标准，实质上只考虑了涝灾的一个致灾因子——暴雨。这种考虑单一致灾因子的重现期标准没有反映出多种致灾因子对涝灾的共同影响，不能正确衡量涝灾发生的概率。本文以平原河网地区的排涝问题为例，采用Gumbel—Hougard Copula函数建立了暴雨和外江水位的联合概率分布模型，研究了在暴雨和外江水位共同作用下的涝灾概率、以及不同量级的暴雨和外江水位组合下的联合分布概率和条件概率。研究结果表明，考虑多种致灾因子共同作用下的涝灾概率更能真实地反映涝灾实际发生的概率，基于Copula函数构建的多变量联合概率模型，可以很方便地计算多种致灾因子的各种量级组合下灾害发生的概率。%Floods are often caused by various hydrological factors, while, traditional drainage criteria is usually defined based on the frequency analysis of rainstorm events. Such kind of drainage criteria based on univariate frequency analysis of rainfall does not reflect the joint action of multivariate hydrological factors on flooding, and it cannot measure the occurrence probability of flooding caused by various hydrological factors. Taking the drainage problem in river network area as an example, where the rainstorm and high water level in outside river are the two main factors causing flooding, the Gumbel-Hougard Copula were applied to construct the joint probability distribution model of rainstorm and water level in outside river. The occurrence probability of flooding under the two main factors were analyzed, and the joint probability and conditional probability of different combinations of various magnitude rainfall and water level were calculated. The results show that the flooding probability under joint action of multivariate hydrological factors can re- flect the true occurrence probability of flooding, and flooding probability under different combinations of multivariate hydrological factors can be easily obtained by multivariate joint probability distribution model based on Copula method.
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