1960—2019年永定河流域降水演化特征

Precipitation Evolution Characteristics of Yongding River Basin in 1960-2019

基于永定河流域内及周边53个气象站1960—2019年逐日降水资料及其插值数据,采用多种变异诊断方法研判永定河流域降水演化特征,结果表明:1)年降水量存在下降趋势,夏季降水量下降趋势显著,春季、秋季、冬季降水量呈上升趋势;2)在空间上,年降水量在大部分地区呈不显著的下降趋势,官厅水库以下较小的范围呈显著下降趋势,春季、秋季和冬季降水量基本呈不显著上升趋势,仅在部分区域呈不显著下降趋势,夏季降水量与其他季节相反,在流域大部分范围呈下降趋势;3)降水要素存在突变性,突变后年降水量的变化为极小值增大、极大值减小,7—8月降水量的变化为整体降低。

Based on the daily rainfall data and interpolation data of 53 meteorological stations in and around the Yongding River Basin in the past 60 years,the evolution characteristics of precipitation in the Yongding River Basin from 1960 to 2019 were analyzed by various variation diagnosis methods.The results show that a)the annual rainfall in the Yongding River Basin has a downward trend.On the seasonal scale,the summer rainfall has a significant downward trend,and the spring,autumn and winter rainfalls have an upward trend.b)In terms of spatial distribution,the annual precipitation shows an insignificant downward trend in most areas,a significant downward trend in a small area below the Guanting Reservoir,and an insignificant upward trend in spring,autumn and winter,only an insignificant downward trend in some areas.On the contrary,the summer precipitation shows a downward trend in most areas of the basin.c)After the abrupt change of precipitation,the distribution function of annual precipitation increases at the minimum value and decreases at the maximum value,and the distribution function of precipitation in July and August decreases as a whole.