云南省日极端降水概率特征及时空变化研究

不同重现期的暴雨设计值是推求设计洪水的基础。选取云南省29个气象站1960―2014年日降水资料,采用极大值法和超门限峰值法2种选样方法构成研究数据序列,通过K-S检验、L-矩法和日极端降水等值线图等方法分析了云南省日极端降水的概率特征及时空变化。结果表明,Wakeby分布函数较好地拟合了云南日极端降水序列;不同重现期下,云南省日极端降水量高值区位于滇南江城、勐腊一带,低值区位于滇西北德钦、中甸一带,极端降水量从南向西北呈阶梯状递减。分别计算不同重现期下的日降水量,时段极大值法设计值均大于以日极端降水资料95th分位数作为阈值的超门限峰法设计值。多数气象站基于Wakeby分布计算出的日极端降水设计值大于PⅢ分布函数设计值。

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

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.