东江流域极端面雨量分布特征及重现期分析

Distribution Characteristics of Extreme Area Rainfall and Estimate of Rainfall During Return Periods in Dongjiang River Basin

基于1967—2021年东江流域11个国家气象站逐日降水量资料,通过百分位法确定极端面雨量相对阈值并定义极端面雨量指数统计方法,分析东江4个子流域极端面雨量时空分布特征,最后选用最优拟合分布函数估算不同重现期下的极端面雨量。结果表明,东江各子流域年极端面雨量和日数的年际变化趋势相似且均呈现不显著减少趋势,年极端面雨量日数多(少)的年份对应年极端面雨量强(弱)的年份;中上游子流域的年极端面雨量年代际变化和极端性变化特征较一致,下游子流域的年极端面雨量年代际变化特征与其他子流域相反;不同重现期下估算的子流域年极端面雨量由大到小排序为白盆珠>东江干流>新丰江>枫树坝,各子流域年极端面雨量估算值在15 a重现期尺度内呈迅速增长态势。

Based on the daily precipitation data of 11 national meteorological stations in the Dongjiang River Basin from 1967 to 2021,the relative threshold of extreme area rainfall is determined by percentile method and the exponent statistical method of extreme area rainfall is defined.The spatiotemporal distribution characteristics of extreme area rainfall in the four sub-basins of the Dongjiang River Basin are analyzed.Finally,the optimal fitting distribution function is selected to estimate the extreme area rainfall under different return periods.The results showed that the interannual variation trend of annual extreme area rainfall and days in each sub-basin of Dongjiang River Basin is similar and shows no significant decrease trend.The year with more(less)annual extreme area rainfall days corresponds to the year with strong(weak)annual polar end rainfall.The interdecadal variation and extreme variation characteristics of annual extreme area rainfall in the middle and upper reaches of the sub-basin are relatively consistent,while the interdecadal variation characteristics of annual extreme area rainfall in the lower reaches of the sub-basin are opposite to those in other sub-basins.The estimates of annual extreme area rainfall in each sub-basin under different return periods were ranked as Baipenzhu sub-basin>Dongjiang main stream basin>Xinfengjiang sub-basin>Fengshuba sub-basin.The estimates of annual extreme area rainfall of each sub-basin shows a rapid growth trend within the 15a return period.