基于滑动Copula函数的金沟河流域径流-气温关系变异诊断

为探究变化环境下金沟河流域径流和气象因素的关系变异情况,根据八家户水文站1964—2016年的水文气象数据,采用极点对称模态分解(ESMD)方法、Spearman相关分析和滑动Copula函数对流域内水文气象要素进行了分析。结果表明:金沟河流域的径流序列整体上呈微弱的减小趋势,降水和气温序列呈增加趋势,ESMD趋势项反映出金沟河流域的径流、降水和气温序列均呈非线性趋势变化;降水和气温序列的突变时间分别为1983年和1997年,径流序列的突变时间为2002年和2015年;滑动Copula函数不同窗口下的相关系数显示径流-气温关系变异时间为1997年,联合序列的最佳Copula函数由1964—1997年阶段的Gauss-Copula函数变异为1998—2016年阶段的Gumbel-Copula函数。气候变化和人类活动是造成金沟河流域径流-气温关系变异的主要原因。研究结果有助于了解金沟河流域内水文气象要素的变化特征及径流气象要素的关系变异时间,可为流域内的其他水文计算提供参考依据。

Variation Diagnosis of Runoff-Temperature Relation in Jingou River Basin Based on Sliding Copula Function

To explore the variation of relations between runoff and meteorological factors in Jingou River basin under varying circumstances, we examined the variations of hydrometeorological factors and the variations of relations between meteorological factors and runoff by using ESMD (Extreme-point Symmetric Mode Decomposition), Spearman's correlation analysis, and sliding Copula function based on the hydrometeorological data of Bajiahu hydrological station from 1964 to 2016. Results suggest that the runoff series of Jingou River basin displays a weak decreasing trend in general, while the precipitation and temperature series show an increasing trend. The ESMD trend item reflects that the runoff, precipitation and temperature series of Jingou River basin vary in a non-linear trend. The precipitation series and temperature series change abruptly in 1983 and 1997, respectively, while runoff series in 2002 and 2015. The correlation coefficients under different windows of the sliding Copula function indicate that the runoff-temperature relation varied abruptly in 1997. The optimum Copula function of the runoff-temperature joint series varied from the Gauss-Copula function in 1964-1997 to the Gumbel-Copula function in 1998-2016. Climate change and human activities are the dominant reasons for the variation of runoff-temperature relation in Jingou River basin.