Temporal and Spatial Distributions of Droughts in Southwestern China in 1960-2011

Based on meteorological data of 130meteorological stations in the southwest of China from 1960to 2011,we have calculated standardized precipitation index(SPI)on different time scales,adopted the Mann— Kendall trend analysis method and inverse distance weighted interpolation method,and analyzed the spatiotemporal variation characteristics of drought in the southwest in the past 52years.The results indicate as follows:(1)In the aspect of annual variation,there was a notable inter-annual fluctuation in the southwest of arid region,and the linear trend was more obvious.Especially the drought frequency has significantly increased in the past 12years.In most areas,the drought index showed a decreasing tendency,with the most obvious decrease in autumn,while that in winner was opposite.(2)In the spatial distribution of the southwest,the spring drought mainly distributed in Hengduan Mountains,Guangxi Hilly,the east of Sichuan Basin and the southern part of Guizhou Plateau.The summer drought was mainly located in the north of Hengduan Mountains,Zoige Plateau,the western and southern part of Sichuan Basin,the central part of Yunnan Plateau hilly,and Guangxi Hilly.The areas with higher incidence of autumn drought were mainly located in the south of Yunnan Plateau,the southwest of Hengduan Mountains,Guizhou Plateau and Guangxi Hilly. The winter drought mainly concentrated on the Zoige Plateau and the southwest of Sichuan Basin.