Multi-objective optimization of seasonal emergency storage in cascade reservoirs for enhanced drought resilience and hydropower synergy

Optimizing the seasonal emergency storage capacity (SESC) of cascade reservoirs is crucial for enhancing water supply and hydropower generation (HG), particularly in the face of extreme drought events. However, this task becomes exceptionally challenging due to the complex interplay of spatiotemporal drought variability and the topographically intricate nature of the basin. This study presents a multi-objective optimization framework for enhancing SESC in cascade reservoirs to simultaneously improve HG and drought resilience. Using a dynamic drawdown strategy, the model incorporates spatiotemporal drought variability and reservoir constraints. Applied to a five-reservoir cascade on the Yangtze River, the model outperforms the standard operation policy (SOP), yielding an 8.7% increase in hydropower output, a 45.5% reduction in river drought duration, and a 4.5% improvement in low-flow conditions. The framework offers robust decision-making support for climate-adaptive water resource management.