摘要:By using the monthly rainfall records of Tongzi, Xishui, Zunyi for 56-63 years, the grade of droughts in the study area was judged and statistically analyzed.The percentage of different grade droughts in the total is: mild drought 47.4%~52.9%, moderate drought 26.0%~31.4%, severe drought 12.1%-14.0%, extreme drought 7.0%~10.4%.The an-nual drought occurrence frequency is: Tongzi 3.5 times, Xishui 3.4 times, Zunyi 3.6 times.The decadal occurrence of droughts showed an increasing trend as:Zunyi 0.078 times, Xishui 0.084 times, Tongzi 0.13 times.The variability of SPI in represent months of four seasons implies that the frequency and intensity of droughts has increased in recent years.The occurrence cycle of droughts got from wavelet analysis are:9~10 years, 13~14 years, 18~22 years.%利用桐梓、习水、遵义三地56-63年的降水资料,采用SPI(标准化降水指数)对遵义市赤水河上游的气象干旱进行了分级判别,利用线性倾向估计、小波分析方法分析其变化趋势和发生周期。研究结果显示,统计时段内各类干旱:轻旱47.4%~52.9%,中旱26.0%~31.4%,重旱12.1%~14.0%,超旱7.0%~10.4%。年均干旱发生的月数:桐梓3.5个月/年,习水3.4个月/年,遵义3.6个月/年。干旱发生次数变率:遵义0.078次/10年,习水0.084次/10年,桐梓0.13次/10年。三地四季代表月(1月、4月、7月、10月) SPI的变率在-0.072~0.056/10年,除1个代表月为正值外,其余三个代表月为负值,表现出不同方向的变化趋势。研究区的气象干旱存在多时间尺度特征,主要周期为:9-10年,13-14年,18-22年。由于研究区属于地形、地貌多变的山地区域,三地干旱频率和等级存在区域差异,总体变化表现为:干旱发生次数逐年增加、干旱等级逐年加重。