清江流域近60 a日降水特征变化分析

Analysis of daily precipitation characteristics over Qingjing River Basin in recent 60 years

基于清江流域11台站1961―2020年期间逐日降水数据,按小雨、中雨、大雨、暴雨降水强度分类,采用线性趋势分析、突变检验等方法分析了各类降水频率、贡献率的变化趋势及其对清江流域降水变化的影响。结果表明:1)近60 a来,清江流域年降水量主要受大雨频率的影响;2)年降水量、年降水日数分别以3.0 mm/(10 a)、0.96 d/(10 a)的速率下降,其中中雨贡献率下降趋势最大,夏季降水量、降水日数及各等级降水贡献率、频率均呈上升趋势,其中暴雨贡献率上升趋势最大;3)春、秋季降水量在20世纪70年代后期突变为下降趋势,二者突变的内在因素分别是暴雨频率和大雨频率的突变;4)降水量、降水日数在高于流域平均海拔区域呈明显下降趋势,二者分别主要受暴雨雨量变化、小雨日数变化的影响。

Daily precipitation data during 1961-2020 from 11 national meteorological stations over the Qingjiang River basin are used in this study.The trends and variations of the contribution and frequency for 4 kinds of precipitation(light rainfall,moderate rainfall,heavy rainfall and torrential rainfall),as well as their impacts on the precipitation variations are analyzed based on linear trend estimate and mutation test methods.The results show that:1)in the past 60 years,the annual rainfall was mainly influenced by the heavy rain frequency.2)The amount and days of annual rainfall decreased at a rate of 3.0 mm/(10 a)and 0.96 d/(10 a),respectively,and the moderate rainfall contribution rate decreased the most.The amount,frequency,and the contribution and frequency of each grade of summer rainfall showed an increasing trend,among which the contribution rate of rainstorm was the greatest.3)Spring and autumn rainfalls showed abrupt changes in the late 1970s,the internal factors of both abrupt changes were the abrupt changes of torrential rainfall frequency and heavy rainfall frequency,respectively.4)The amount and the number of precipitation days of annual precipitation showed obvious decreasing trends in the region above mean elevation of the basin,which were mainly influenced by the changes of torrential rainfall and light rainfall days,respectively.