利用淮河流域28个国家基本气象站建站（约1951—1958年）以来至2011年间的月值地面气象观测数据,分析了近60年来干旱的趋势特征以及极端降水特征对干旱特征的影响。对不同时间尺度（1月、3月、12月）的标准化降水指数SPI及湿润指数HI的变化特征分析表明,在1个月和3个月尺度上,春季（尤其是4月）有较一致的气象干旱化与湿润度下降倾向,而夏季（尤其是7—8月）有较一致的湿润化趋势;在12个月尺度上,流域中、西部没有显著的气象干湿变化趋势,但西部有普遍湿润化倾向,东部则同时存在气象干旱化与湿润度下降倾向。由于全流域总降水量无显著变化,而潜在蒸散发量呈减少趋势,使得淮河流域在过去60年间湿润指数（HI）总体有所增大。由于整个淮河流域的日降水量≥0.1mm日数总体呈显著下降趋势,导致降水总体有更加集中的趋势,而降水的集中程度与标准化降水指数（SPI）具有一定的负相关性,因而降水更集中使SPI趋于减小,加大发生气象干旱的可能性。%The trend of drought and its relationship with extreme precipitation events in Huaihe River basin over the last 60 years were analyzed using the observations at 28 meteorological stations during the period from the start of their observation(mostly started in 1951—1958) to 2011.According to the results of standard precipitation index(SPI) and humidity index(HI) at different time scales(from 1 month to 12 months),at 1-month and 3-month scale,there is a general tendency of drying in the spring(especially in April) and wetting in the summer(especially July and August);at 12-month scale,no trend is observed in SPI in the west and middle part of Huaihe River basin,but a widespread increase in HI is observed in western part;at 12-month scale,there is a general tendency of drying in eastern part with respect of both SPI and HI.There is significant decrease in potential evapotranspiration over the whole basin,and due to the decrease in potential evapotranspiration,HI exhibits a general tendency of increase which indicating the increase of the proportion of humid area in Huaihe River basin.There is a significant decrease of the number of rainy days(precipitation amount is greater than 0.1mm),resulting in a general tendency of more intense precipitation than the past.It is found that precipitation intensity is negatively related with SPI,as a result,the possibility of meteorological drought occurrence is increased.
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