Integrated Approach to Modelling and Forecasting Water Balance under Climate Change in Southern Laos Using Hydrological Model

Climate change is affecting global rainfall patterns and soil moisture, leading to droughts and unpredictable weather. Southeast Asia, particularly Laos, is experiencing increased droughts due to climate change. This study examines the dynamics of the water balance in southern Laos between 2018 and 2022 and assesses the impact of deep drainage, runoff, and evapotranspiration. It provides observations on water retention, vulnerability to floods, and sensitivity to droughts in the region. The results show that 63.5% of the water balance highlights the region’s significant infiltration capacity due to sandy loam soils and limited surface sealing. Runoff makes up 30% and has sudden increases during the monsoon rains. Evapotranspiration is very low at 6.4% and is possibly regulated by the dense vegetation and tropical monsoon environment. The model evaluation metrics ([Formula: see text], [Formula: see text], [Formula: see text][Formula: see text]mm) indicate a robust simulation performance, especially during the runoff peaks. A further investigation of drought indices (SPI-6), vegetation responses (MSAVI), and runoff coefficients clarifies the relationships between precipitation, infiltration, and surface runoff. This research can help with planning water management and improving farming in areas with heavy monsoon rains.