Characterization of Hydro-meteorological Extremes and Climate Change Projection for Predicting Water-induced Disasters in Songkhram River Basin, Thailand

Extreme climatic and hydrologic events cause water-induced catastrophes which correspond to damage and loss to life, economies, and properties. Water resources and rivers around the world are influenced by several climatic, topographical, and human factors which are further worsened by the impact of climate. This study examines the regional variability and the trend in hydro-climatic extremes and their historical, and future projections for the Songkhram River Basin in northeast Thailand. To describe the extremes, a total of 22 hydro-climatic indices were chosen out of which 8 hydrological computed indices were Indicators for Hydrological Alteration, and 7 were related to temperature and rainfall calculated using Climpact. For the historical period (1990-2019), the results showed rising trends in rainfall and temperature extremes, with a rate of increase of 30-35% in RX1day (monthly maximum 1-day rainfall), 4-10% in R95p (very wet days rainfall amount), and 10-50% in warm nights from the base period until the mid-century. Hydrological extremes demonstrate an upward trend in the magnitude with the rate of increase of 10-90% in 1,3, & 7-day maximum flows, and a drop in annual lowest flows by -80-10% 1, 3, & 7-day minimum flows. Results also show that the duration of high flow is decreasing and low flow is increasing. In addition, as a result of the direct association between hydro-climatic extremes, floods and droughts are anticipated to rise in the future.