基于Copula的韩江支流丰枯径流频率分析

Analysis on Drought and Flood Flow Probability in Hanjiang River Tributary Based on Copula Function

以往的重现期推求基本上是采用单变量频率分析方法划分洪旱,无法考虑丰枯径流与丰枯历时引起的联合变化。以韩江最大两条支流梅江及汀江为例,采用常用Gumbel-Hougaard Copula函数,计算枯水历时和枯水烈度、丰水历时和丰水烈度的联合重现期和同现重现期,探讨两支流丰枯径流变化规律,分析两支流丰枯变化原因。结果表明:(1)梅江枯水事件发生频率比汀江小,但干旱一旦发生,其严重程度比汀江大;(2)在单变量设计重现期为100年一遇的情况下,梅江、汀江枯水历时与枯水烈度、丰水历时与丰水烈度的联合重现期在52~64 a之间,比单变量重现期小36~48 a。推求多因素影响下的联合分布与联合重现期,为梅州市科学确定洪旱重现期,提高水安全保证度提供依据。

The univariate frequency distribution results derived from traditional methods is unable to reflect the true frequency distribu- tion under changing environments. In this paper, we will focus on two largest tributaries of Hanjiang River（ Meijiang river and Tingjiang river） and use Gumbel - Hougaard copula function and daily streamflow data to analyze the probability Variation of drought and flood. The results showed that. （1）The frequency of drought inMeijiang basin was lower than Tingjiang basin, but once the droughtoccurred, it would be more serious than Tingjiang basin. （2） If univariate designedtohundred - year return period, the joint return period of the drought duration and drought intensity, flood flow duration and flood degree were between 52 years and 64 years, less than univariateret- urn period（ 36 years to 48 years）. Calculating the joint distribution and joint return under the influence of multi - factors, it will provide a basis for determine of drought - flood return period and improvement of water safety in Meizhou.