基于SPEI的四川省盆地区季节性干旱时空变化特征分析

SPEI-based analysis of temporal and spatial variation characteristics for seasonal drought in Sichuan Basin

基于四川省盆地区1961-2012年57个台站逐月气温和降水数据,利用标准化降水蒸散指数(SPEI)对盆地区近52 a季节性干旱的时空分布特征及变化趋势进行分析。结论表明,(1)在季节性增暖和少雨趋势协同作用下,盆地农区春夏秋冬四季干旱化加剧,其中秋季增温率达0.154℃·10 a^(-1),且降水以15.22 mm·10 a^(-1)的速率减少,干旱化趋势在四季中最为显著。(2)对比不同等级的干旱,秋季中旱站次的增加趋势最为突出;从1990 s后期开始春夏秋冬四季重旱和特旱站次大体上呈增加趋势,极端干旱灾害影响扩大。(3)四季盆地区域干湿分布特征和变化趋势均存在显著的空间差异,其中盆西平丘区、盆中丘陵区和部分盆南缓丘区是季节性干旱化倾向较为明显、干旱影响面积较大的地区,需要加强防灾减灾措施,以规避干旱事件增多带来的不利影响。

SPEI-based analysis of temporal and spatial variation characteristicsfor seasonal drought in Sichuan BasinBased on the data of monthly precipitation and temperature from 57 meteorological stations during 1961-2012,the inter-seasonal standardized precipitation evapotranspiration index(SPEI)was calculated to analyze the temporal and spatial variation of seasonal drought in Sichuan Basin.The results showed as followings.First,due to the seasonal increase in temperature and decrease in precipitation,the four seasons of Sichuan Basin tended to be dry,and it was especially typical in autumn.The meteorological data demonstrated that the increase rate of autumn temperature was 0.154℃·10 a-1 in Sichuan Basin,and the autumn precipitation was decreasing significantly by the rate of 15.22 mm·10 a-1.Second,compared to other degrees of drought,the number of moderate drought stations in autumn had the most significant increasing trend,and it was found that an increasing trend for the number of severe drought and extreme drought stations occured since the late 1990s,resulting in the enhancing impact of drought obviously.Third,there were significant spatial differences in characteristics of regional dryness/wetness distribution as well as the variation trend in the four seasons of Sichuan Basin.The obvious drought-prone areas impacted by drought severely were located in the flat-hilly areas in the west of Basin,the hilly areas in the middle of Basin,and the mild hilly areas in the south of Basin.To these regions,it was necessary to strengthen the corresponding drought prevention measures in time to avoid the influence of extreme drought events.