青海省玉树旱涝态势变化规律分析

Change Analysis of Droughts and Floods in Yushu County of Qinghai Province

选取青海省玉树1953~2013年月降水数据,基于标准化降水指数SPI,利用频率分析、小波周期分析等方法对玉树县近61年来旱涝强度、频率分布、周期性变化等旱涝态势演变特征进行了研究。研究结果表明：（1）SPI-3、SPI-6和SPI-12三种尺度标准化降水指数对旱涝指示程度存在差别,相比大时间尺度,小时间尺度的标准化降水指数值更为分散,波动幅度更大,对干旱和洪涝的识别更为敏感。近年来,随着玉树县水土流失和沙化,当地土壤持水力程下降趋势,对干旱和洪涝较为敏感,因此玉树县可采用三种尺度标准化降水指数。（2）近61年,玉树县重旱平均发生概率为2.1%,重涝平均发生概率为1.3%。（3）未来几年,预计玉树县仍呈现偏涝趋势。（4）玉树县SPI-12以18a为主周期进行变化。

Selecting precipitation data of Yushu County from 1953 to 2013, based on standardized precipitation index（SPI）, the drought and flood intensity, frequency distribution and periodic characteristics of Yushu County were studied by using the frequency analysis, wavelet cycle analysis and other methods. The results show that（1） there are different drought and flood indicator degrees between the three scales of standardized precipitation indexes（SPI-3, SPI-6and SPI-12）;（2） In recent 61 years, the occurrence probability of severe droughts is 2.1%, the occurrence probability of severe floods is 1.3%;（3） In Yushu County, the flood frequency will increase in next few years;（4） The precipitation changes with a primary period of 18 a in Yushu County.