甘肃省近48年春旱时空变化趋势分析

Temporal and Spatial Variation Trend Analysis of Spring Drought in Gansu Province in Recent 48 Years

甘肃省春旱频发,针对已有的文献对春旱趋势特征研究的不足,选取甘肃省境内的30个气象台站1962—2010年的月降水数据,基于标准化降水指数,采用Mann-Kendall非参数趋势检验法和小波分析等方法对甘肃省春季SPI的时空变化特征和周期特征进行研究.结果表明:甘肃省春季SPI以-1.16/10 a的速度下降,春季干旱呈加快趋势;甘肃省春季干旱发生频率为41%,中旱以上发生频率约为20%,重旱以上发生频率约为3.6%;春季SPI以13 a为主周期变化;全省春旱呈现自西北地区向东南地区加速的趋势,其中以陇南地区春旱加速趋势最为明显.研究结果可为甘肃省抗旱减灾提供决策参考.

Spring drought in Gansu province emerges frequently. Because of the insufficient in the study of spring drought trend charac-teristics, selecting monthly precipitation data from 30 meteorological stations from 1960 to 2008 and using Mann-Kendall non-parametric trend analysis and wavelet analysis, spatial and temporal variation together with the periodic feature of spring drought in Gansu province are investigated on the basis of the spring standardized precipitation index （ SPI）. The results indicate as follows： Firstly, the spring SPI decreases with a rate of - 1.16/10 a, which means a increasing trend of spring drought in these years; Secondly, the frequency of spring drought occurrence is 41% in Gansu province, the frequency above medium drought is about 20% , and the frequency above se-vere drought is about 3.6% ; Thirdly, the spring SPI varies with a primary period of 13 a; Fourthly, Gansu province suffers spring drought with a gradual increasing trend from northwest to southeast, especially in Longnan area, spring drought has a most obvious in- creasing trend. The results could provide a decision reference for drought control in Gansu province.