基于Copula函数的河川径流丰枯遭遇分析

Synchronous-Asynchronous encounter probability of rich-poor runoff based on copula function

【目的】研究两变量联合概率的分布问题,探讨干支流的丰枯遭遇分析方法。【方法】采用Copula函数,构建了渭河干流及其支流千河年径流的联合概率分布模型,对干支流的丰枯遭遇进行分析,并绘制了干支流联合分布等值线图。【结果】宝鸡市渭河干流年径流量的边际分布服从皮尔逊Ⅲ型分布,而支流千河年径流量的边际分布服从对数正态分布,且干支流同时出现丰水年的概率大于同时出现平、枯水年的概率。【结论】用Copula法描述干支流的丰枯遭遇问题具有可行性。

【Objective】The research studied the joint probability distribution with two variables and analyzed the synchronous-asynchronous encounter probability of rich-poor runoff of mainstream and tributary.【Method】The copula theory was applied to construct the joint distribution of annual runoff in the Wei River and the Qian River,the biggest branch of Wei River in Baoji City.The synchronous-asynchronous encounter probability of rich-poor runoff was analyzed and the contour map of the joint distribution was obtained.【Result】The marginal distribution of the annual runoff in the Wei River obeys P-Ⅲ distribution,while that in the Qian River belongs to lognormal distribution,and the synchronous encounter probability of rich runoff in both rivers is greater than the probability of poor and normal runoff.【Conclusion】It is feasible to apply Copula function to describe the synchronous-asynchronous encounter probability of rich-poor runoff in mainstream and tributary.