Integrated WEAP-Hippopotamus Optimization Framework for Climate-Resilience Reservoir Operation: A Case Study of Ubolrat Reservoir, Thailand

Climate change leads to reservoir management challenges especially in areas with high risk of drought and flood. Traditional reservoir rules curves are inappropriate for addressing variation of reservoir inflow. This study presents an integration framework between GCMs from CMIP6 (ACCESS-CM2, MIROC6, and MPI-ESM1-2-LR) under SSP245 and SSP585 scenarios and WEAP, which is validated in accuracy for reservoir inflow and storage capacity. This integration contributes to Hippopotamus Optimization (HO), a technique used to develop Resilience Reservoir Rule Curve (RRRC) for Ubonrat reservoir during 2024-2055 employing dual-objective function that emphasizes the reduction of water shortage and water excess. The results indicate that RRRC developed by HO is more efficient and suitable than Honey Bee Mating Optimization (HBMO) and existing rule curve. After testing the RRRC with historical inflow and future inflow from three GCMs under SSP245 and SSP585, it can reduce average water shortage and demonstrate outstanding efficiency in water excess management. This potential reflects its adaptability under future variation of hydrological condition. This crucial finding illustrates that the integration framework can develop resilient rule curves under uncertainty. HO integrated with various models can be implemented as an optimal framework and have high potential for reservoir operation planning under climate change. The developed methodology can be implemented in other reservoirs to gather additional factors for sustainable promotion of water resource resilience.