1961-2008年淮河流域主汛期极端降水事件分析

摘要

Using the daily precipitation data of rainy season (June to August) from 1961 to 2008 of 117 stations over the Huaihe River Basin, the extreme precipitation thresholds are determined for different stations by means of the percentile method, and then the time series of extreme precipitation events in recent 48 years is constructed, by which the characteristics of temporal-spatial variations of extreme precipitation events are analyzed. The results show that the inter-annual variation of extreme precipitation is remarkable over the Huaihe River Basin in rainy season, and the amount of extreme precipitation corresponds well with the droughts and floods. The frequency of extreme precipitation events greatly affects the amount of total precipitation in rainy season. The consistency distribution is the main spatial mode in the frequency of extreme precipitation events in the Huaihe River Basin, which can be divided into five main regions: central and eastern, central and north, southwest, northwest, and southern. The amount and frequency of extreme precipitation for the Huaihe River Basin have obvious increase trends in general since the 1960s, and the most significant increasing tendency occurred in the central and western Huaihe River Basin in particular. There are periodic variations of 2 to 3 years in the frequency of extreme precipitation events over the Huaihe River basin in rainy season. There occurred an abrupt change around 2003, and the frequency of extreme precipitation events increased significantly at a significant level of 0.05 since 2003.%利用淮河流域117个台站1961-2008年主汛期(6-8月)逐日降水资料,采用降水百分位数法划分极端降水阈值,建立极端降水事件时间序列；在此基础上揭示淮河流域极端主汛期降水事件时空演变特征.结果表明:淮河流域主汛期极端降水总量年际变化大,其强弱与旱涝格局基本对应.极端降水事件发生频次的多寡很大程度上影响着淮河流域主汛期降水量.一致性分布是淮河流域主汛期极端降水事件发生频次的最主要空间模态,其发生频次空间上可分为流域中东部、中北部、西南部、西北部及南部5个主要区域.极端降水事件总体上有增加趋势,特别是流域中西部地区线性增加趋势达到0.05显著水平.极端降水事件发生频次最典型周期为2～3年的震荡；2003年左右极端降水频次发生突变,2003年以后增多趋势显著.