OPTIMAL OPERATING RULE CURVES FOR IMPROVING A MULTI-PURPOSE WATER ALLOCATION STRATEGY OF THE UBOL RATANA RESERVOIR

Effective water resource management is critical for sustaining agricultural irrigation and mitigating significant seasonal operational challenges, particularly at the Ubol Ratana Reservoir in Thailand. This study proposes a multi-objective optimization framework aimed at simultaneously minimizing water shortage volumes and excess water overflow. To achieve this, two advanced metaheuristic algorithms-the Genetic Algorithm (GA) and Invasive Weed Optimization (IWO)-were integrated with a reservoir simulation model to develop optimized operational rule curves. The results demonstrated that the optimized rule curves significantly enhance water management performance. The GA method yielded the lowest average water shortage volume at 380.223 Million Cubic Meters (MCM) and an average water surplus (overflow) of 396.779 MCM. In comparison, the IWO method resulted in an average water shortage of 420.188 MCM and an average water surplus of 439.690 MCM. Crucially, the practical applicability of the optimized strategy was ensured through a participatory approach used to estimate agricultural water demands and propose adaptive cropping plans. These findings offer a robust and sustainable methodology for enhancing the multi-sectoral management of water resources in Thailand.