长江中下游地区是我国重要的粮棉油产地之一，但是频繁发生的旱涝灾害经常造成该区域作物减产。本文利用长江中下游地区72个气象站的逐月气象观测数据，采用标准化降水指数(SPI)、正交经验分解函数（EOF）等方法，结合GIS技术，分析了近50a长江中下游地区旱涝时空变化分布特征。结果表明：长江中下游地区的旱涝SPI3空间格局既有全区一致的现象，也存在区域内部南北、东西方向的差异,但是其主要特点依然为纬向分布型。由于受气候影响，长江中下游地区夏秋两季旱涝灾害交替发生，但以涝灾为主。

The middle and lower reaches of the Yangtze River are important production bases of grains, cotton and oil crops in China, where droughts and floods occur frequently, which often result in the reduction of crop output. In this paper, based on the monthly meteorological data of 72 meteorological stations in the Yangtze River region, the temporal and spatial variation in droughts and floods of the Yangtze River region in near 50 years was analyzed using standardized precipitation index (SPI), empirical orthogonal function (EOF), and geo-statistical analysis combined with GIS technology. The results showed that the spatial distribution pattern of droughts and floods SPI3 in the Yangtze River region was almost the same in the whole region, but there was a difference in the south-north direction. Due to the climate, droughts and floods in Yangtze River region appeared alternately in summer and autumn, and the flood disaster occurred mainly in the critical period of growth and development of crop.

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