Space-time characterization of droughts in the Mae Klong River Basin, Thailand, using rainfall anomaly index

Abstract

Drought is a slow-onset natural hazard that has major social, economic, and environmental consequences. This study examined the temporal and spatial characteristics of meteorological droughts in the Mae Klong River Basin, Thailand, during 1971–2015. The rainfall anomaly index (RAI) was calculated for 3, 6, and 12 months using monthly observed rainfall data from eight stations. The RAI results showed the presence of multiple drought events ranging from moderate to severe conditions over the study period. Trend analysis was carried out for the drought duration, magnitude, and intensity using the Mann-Kendall test and the Sen’s slope method. Increasing trends were found for drought intensity for both the 6- and 12-month time scales. The performance of RAI was assessed by comparison with the standardized precipitation index (SPI). In general, a high correlation (Pearson’s coefficient r>0.93) was found between RAI and SPI. Cohen’s Kappa test indicated fair agreement between the results of the two drought indices. The findings of this study are expected to help decision-makers better manage the basin’s water resources.