未来气候情景下淮河中上游降水极值及其联合概率行为变化特征

极端气候变化导致水旱灾害频率和强度的改变,为探究未来气候情景下淮河中上游降水极值及其联合概率行为变化规律,以淮河干流小柳巷以上32个雨量站1961～1990年实测日降水数据为基准,集合RCP4.5情景下5种全球海气耦合模式(GCM)在2021～2050、2051～2080年的日降水预测,应用6种极端降水指数量化极端降水变化规律,基于Copula函数构造3组极端降水指数组合的联合分布,并利用Kendall重现期探讨双变量降水事件发生概率的空间变化规律。结果表明,无论在哪个未来时段,6种极端降水指数较基准期均有不同程度的增大;双变量降水事件的发生概率的空间异质性随着重现期水平的增高而增大;未来60年北部山区和研究区下游极端降水事件发生更加频繁,对淮河流域防洪排涝具有指示作用。

Changing Characteristics of Precipitation Extremes and Their Joint Probability Behaviors in the Upper and Middle Reaches of Huaihe River Basin Based on Future Climate Scenario

The changes of climate extremes can cause the variation of frequency and intensity of floods and droughts. The goal of this study is to investigate the changes of univariate and bivariate probability behaviors of extreme precipitation in the upper middle reaches of Huaihe River Basin. Based on the observed daily precipitation series of 1961 to 1990 at 32 rainfall stations above the Xiaoliuxiang hydrological station, multi model ensembles of five GCM simulations under RCP4.5 scenario of 2021 to 2050 as well as 2051 to 2080 were obtained. Six extreme precipitation indices were applied to quantify the changing characteristics of extreme precipitation. The bivariate distributions of three precipitation indices combinations were constructed by using copula functions, and Kendall return period were employed to analyze the spatial variability of the probability of bivariate precipitation events. The results indicate that no matter in which future period, the values of six precipitation indices increase, albeit to varying degrees. With the return period increasing, spatial heterogeneity of the probability of different bivariate precipitation event increases accordingly. There will be more frequent extreme precipitation in the northern mountains and the downstream region, serving as an indicator for flood control in Huaihe River Basin.