长江流域极端降雨事件时空分布特征

近年来,许多学者对中国的极端降水进行了研究,但对长江流域极端降水的研究多集中在日时间尺度强降水事件,从不同子流域极端降水事件入手的研究较少。利用1961～2017年长江流域各子流域面雨量资料,根据面雨量的分布曲线确定长江流域各子流域极端降雨事件判断的阈值,得到各子流域极端降雨年份,分析极端降雨事件的时间变化特征,以及不同子流域间极端事件的相关关系。研究表明:①20世纪60年代长江上游极端多雨事件频发,70年代以全流域极端少雨为主,80年代极端多雨事件中心转移至长江中下游,90年代长江上游变为极端少雨事件中心,2000年以来,长江流域处在由少雨向多雨转变的年代际背景中。②当子流域发生极端少雨事件时,流域其他流域大部也是以降雨偏少为主,空间的一致性较好。但是子流域发生极端多雨事件时,存在大部分地区少雨的情况,会出现旱涝并存的情况。

Spatial and temporal analysis of extreme precipitation events in Yangtze River Basin

In recent years, many scholars have studied extreme precipitation in China, but for the Yangtze River Basin they only focused on heavy precipitation events of daily scale, less research are related to extreme precipitation events in different sub-basins. Based on areal rainfall data in various sub-basins of the Yangtze River Basin from 1961 to 2017, the threshold values of extreme precipitation event judgment for various sub-basins of the Yangtze river basin are determined according to the distribution curve of areal rainfall, so the extreme precipitation year of various sub-basin are obtained. The temporal variation characteristics of extreme precipitation events as well as the correlations of extreme events in different sub-basins are also analyzed. Studies show that: in the 1960s, extremely heavy rain events occurred frequently in the upper reaches of the Yangtze River; in the 1970s, the whole basin was dominated by extremely little rain; in the 1980s, the extreme heavy rain center transferred to the middle and lower reaches of the Yangtze River; in the 1990s, the upper reaches of the Yangtze River became the center of rainless events; since 2000, the Yangtze River Basin has been in the interdecadal background of the transition from the little rain to the heavy rain. When the basin has an extremely rainless event, most of the sub-basins are also dominated by little precipitation, with good spatial consistency. However, in the case of extreme heavy rain events happening in one sub-basin and there is little rain in most other basins, the drought and flood coexist.