基于SPEI的开都河流域干旱时空演变特征分析

Spatial and Temporal Evolution Characteristics of Drought in Kaidu River Basin Based on SPEI

基于开都河流域5个国家基本气象站1961—2020年的逐日气象资料,计算了年和季节为主要时间尺度的SPEI指数数据,并利用Morlet小波分析、Mann-Kendall检验、趋势归因等方法,研究该区域的干旱时空演变规律及其原因。结果表明:近60年,除冬季外,其余时间尺度上的开都河流域均呈干旱化趋势。在空间分布上,流域的年和夏季变化一致,自北向南呈“偏湿—偏干”趋势;春季与秋季变化趋势相同,自西向东呈“偏干—偏湿”趋势;冬季则整体呈“偏湿”趋势。气温是开都河流域干旱变化的主导因素,但流域北部地区干旱变化以降水影响为主,南部地区则受气温影响为主;和静与焉耆区域除冬季外,气温对干旱趋势的贡献均远高于降水贡献,表明该区域干旱化较为严重。开都河流域各时间尺度上的干旱均基本2~6 a一遇,干旱特征多以轻旱为主,中旱次之。其中,春季不仅是重旱事件发生最多时期,还是流域干旱事件发生的主要时期。

Based on the daily meteorological data from 5 national meteorological stations in Kaidu River Basin from 1961 to 2020,the standardized precipitation evapotranspiration indexes(SPEI)on annual and seasonal time scales were calculated.Morlet wavelet analysis,Mann-Kendall test,Trend attribution and other methods were used to analyze the spatial-temporal evolution rules of drought and its reasons in this basin.The results showed that the basin presented an aridity trend during the past 60 years except for winter.Spatially,from north to south in basin,the distribution characteristic was“wetry”trend both year and summer.From west to east in spring and autumn,there was a“dry-wet”trend.The overall trend in winter was“wet”.Temperature was the dominant factors of the dryness changes in the Basin.However,the drought change in the north region and the south region were affected by precipitation and temperature respectively.Except the winter,the contribution of temperature to the dryness trend in Hejing region and Yanqi region exceeded that of precipitation,which indicated that these regions were severely arid.The different time scales drought occurred every 2 to 6 years in basin,which were mainly light drought or moderate drought.Besides,spring was not only the event-prone period with the serious drought,but also the main periods for drought events occurred.