Meteorological Drought Hazard Assessment under Future Climate Change Projection for Agriculture Area in Songkhram River Basin, Thailand

The Songkhram River Basin (SRB) has recently experiencing related drought disaster and water scarcity because of reduction in rainfall and increasing high temperature. This paper presents an assessment of meteorological drought hazard of agriculture area in the river basin under future climate change projection. The study analyzed meteorological drought hazard using the Standardized Precipitation Index or SPI considering the observed daily rainfall data (1970-2010) from 6 meteorological stations and the average trend of the projected future climate change scenarios (2011-2100) from three Regional Climate Models (RCMs) under two Representative Concentration Pathways RCP4.5 and RCP8.5. The results showed that the future annual rainfall in the 21st century at Sakon Nakon weather station in SRB was reduced by -1.5% and -3.7% per decade for RCP4.5 and RCP8.5, respectively. The drought hazard assessment was quantitatively evaluated for rice and field crops based on the values of drought hazard parameters namely: standardized precipitation index SPI, distance from surface water resources and ground water yields. The weights of each drought parameter were determined by using Analytical Hierarchy Process (AHP). The result showed a change in potential drought hazard in the future in the study area of 12,880 km
²
, for SPI1 under RCP4.5; the low hazard area was 33%, medium of 22%, high of 45% in 2020s. They did not change much in 2050s but significantly changed from low to medium, medium to high and high to very high hazard respectively in 2080s. While under RCP8.5; the low, medium, high and very high hazard areas in 2020s significantly changed to medium, high and very high hazard respectively in 2050 and 2080s. A bit more significant droughts was expected to occur for SPI3 which is for field crop for both RCPs. Overall, under both RCP4.5 and RCP8.5, we can say that the droughts become more significant in the study area as the time goes on from 2020s to 2050s and to 2080s for both rice and filed crops. However, the predicted drought conditions were only based on standardized precipitation index SPI1 and SPI3 under predicted climate change conditions. In actual situations, other factors such as evapotranspiration, soil moisture conditions, change in runoff and irrigation as well as adaptation measures may change the results of this study. The temporal pattern of future drought hazard levels can be used by researchers and policy makers as a guideline for drought management and mitigation strategies in the study area.