摘要
Abstract
The aim of the research is to improve the understanding of the temporal and spatial characteristics about precipitation in Yanan.The annual and spatial distribution characteristics,the interannual and spatial variation characteristics of precipitation are analyzed based on precipitation data from 15 rainfall stations in Yanhn from 1956 to 2015.The methods,such as a moving-average,accumulative anomaly,R/S analysis,Mann-Kendall test and wavelet analysis,are used here.The results show that:the annual distribution of precipitation in Yan'an is extremely uneven,precipitation is mainly concentrated in the flood season (June to September),and the precipitation in flood season accounts for 70％ of the whole year precipitation;the annual precipitation shows a decreasing trend of " increase-decrease-increase "fluctuation,whose decline rate is about 8mm/10a,and the annual precipitation changed abruptly in 1969 and the sequence of precipitation has a positive continuity;the first main period of annual precipitation change is 31 years,and it can be forecasted that precipitation of Yan'an in the next few years will decrease according to the periodic feature of 15-year scale;the spatial distribution of precipitation in Yan 'an is uneven,which is characterized by "the southeast is more,and the northwest is less ",and the difference value is more than 130mm.The precipitation in most areas of the city has been declining,the area which declined most quickly is the southwest of Zhidan County,while the precipitation in the south of Huanglong mountain area increased slightly.关键词
降水/时空特征/R/S分析法/Mann-Kendall检验/小波分析/延安市Key words
precipitation/spatial-temporal characteristics/R/S analysis/Mann-Kendall test/wavelet analysis/Yan'an City分类
建筑与水利
