Statistical Analysis and Spatio-temporal Variation of Extreme Rainfalls in Yunnan Province

ZHANG Sufan; WANG Long; YU Hang; WEI Qiong; GAO Rui

doi:10.13522/j.cnki.ggps.2017.05.003

Abstract：Estimating extreme rainfall intensity under different return periods is critical in all hydraulic structure designs.In this paper we calculated the statistics and spatio-temporal variation of extreme rainfalls in Yunnan Province from the rainfall data measured daily from 1960-2017 at 29 weather stations across the province.Time series of extreme rainfalls at each station wascreated firstly using the maximum-value method and the peakthreshold method respectively,and we then analyzed itsspatio-temporal variation in the province using the K-S test,L-momentand the contour map of the extreme rainfalls.The results showed that the daily extreme rainfall series in the province can be described by the Wakeby function.Spatially,the daily extreme rainfall peaks in the south of the province at Jiangcheng and Mengla,and troughsin the west of the province at Deqin and Zhongdian.That is,the daily extreme rainfall decreases from the south to the northwest across the province.We also calculated the daily extreme rainfalls under different return periods and the results showed that the extreme rainfalls calculated using the maximum-value method were higher than those calculated using the peak-threshold method with the 95th interquartile.Also,in most of the weather stations,the daily extreme rainfalls calculated using the Wakeby function are higher than those calculated using the PⅢ distributed function.