Drought characterization in the Mae Klong River Basin, Thailand, using Standardized Precipitation Index

Drought is a creeping natural hazard with a slow-onset and has serious social, economic, and environmental impacts. This study investigated spatial and temporal characteristics of meteorological droughts in the Mae Klong River Basin during the period 1971-2015. Using monthly observed rainfall data for eight stations, the Standardized Precipitation Index (SPI) was calculated for 3, 6, and 12 months. The Mann-Kendall and Sen's slope tests were used to calculate the trends in the annual total rainfall and drought characteristics such as duration, magnitude, and intensity of drought events. Results for climate variability showed that the Mae Klong River Basin has been facing dry years with annual rainfall below a minimum threshold of 1114 mm for the covered period. Results of SPI indicated occurrence of several drought events over the covered period ranging from moderate to severe droughts. More drought events occurred in the lower region of the basin, which is more intense in terms of water demands in the basin. Trends of annual total rainfall were found to be decreasing in the lower region of the basin. Trend analysis of drought characteristics found decreasing trends in drought magnitudes and durations for majority of the stations; however, increasing trends were found for drought intensities. Results of this study could help water resources planners in formulating effective strategies for better management of water resources in the basin.