Drought management in Sri Lanka is mostly limited to relief provision due to the shortage of scientific details to develop sufficient drought risk management. Therefore, spatio-temporal variability of droughts in two cropping seasons, Yala (May–August) and Maha (October–March) in Sri Lanka, have been investigated using the Standardized Precipitation Evapotranspiration Index (SPEI). The SPEI-4 at August (SPEI-4_August) shows an apparent decadal variation over wet, intermediate, and dry climate regions in the country, which is coherent with the decadal shift of rainfall in 1999. For the Yala season, the number of drought events (SPEI-4_August < −1) in the late period (2000–2015) is higher than that in the early period (1985–1999). On the other hand, the decadal variation of SPEI-6_March is not distinguished; however, the number of drought events (SPEI-6_March < −1) in all climate regions is less after 2003 as compared to the early period. The principle component time series of SPEI-4_August and rainfall in Yala seasons (r = 0.93) have closely associated, which implies that rainfall received in the Yala season can ascribe the observed decadal variation in SPEI-4_August. In the Yala season, less moisture transport towards Sri Lanka is observed in the late period due to the weakening of 850 hPa wind circulation and increasing of 500 hPa geopotential height, which causes more moisture divergence and ultimately affects the decreasing rainfall over the country. Meanwhile, the observed rainfall variability in cropping seasons, especially in the Yala season, is characterized by the large-scale circulation at interannual (Nino3.4) to decadal-scale (Pacific Decadal Oscillation (PDO), and North Atlantic Oscillation (NAO).

斯里兰卡的干旱管理主要限于提供救济，因为缺乏科学的细节来发展足够的干旱风险管理。因此，已使用标准化降水蒸散指数（SPEI）调查了斯里兰卡亚拉（5月至8月）和玛哈（10月至3月）两个种植季节的干旱时空变化。SpeI位-4在八（SPEI-4_月）显示了在该国湿，中间，和干燥的气候区域的表观年代际变化，这是相干带大的在1999年年代际变速对于亚拉季节，数量 后期（2000-2015年）的干旱事件（SPEI-4 _August <-1）高于早期（1985-1999年）的干旱事件。另一方面，SPEI-6的年代际变化不区分_三月；但是， 与早期相比，2003年之后所有气候区的干旱事件（SPEI-6 _3月<-1）的数量都更少。的主成分的时间序列SPEI-4的_八月和降雨在也拉季节性（r = 0.93）都紧密结合，这意味着在次季接收降雨可以归于在SPEI-4观察到的年代际变化_八月。在亚拉季节，由于850 hPa的风环流减弱和500 hPa的地势高度增加，后期观测到的向斯里兰卡的水分输送减少，这导致了更多的水分散布并最终影响了该国降雨的减少。同时，在作物季节，特别是在亚拉季节，观测到的降雨变化特征是年际（Nino3.4）到年代际（太平洋年代际涛动（PDO）和北大西洋涛动（NAO））的大规模环流。 。