Refining hydropower operation by dynamic control of cascade reservoir water levels with flood season segmentation

Flood limited water level (FLWL) is a critical factor in managing reservoir operations throughout the flood season. Given the growing need for renewable hydropower, there is an urgent need for new FLWL-centered policies to stimulate hydropower development. This study proposes a dynamic control framework for FLWL of cascade reservoirs based on the segmentation of the flood season (i.e., pre-flood, main flood and post-flood subseasons). Specifically, the dynamic control of reservoir water levels during the pre-flood and main flood subseasons is around seasonal FLWLs to balance flood control risk (FCR) and total hydropower generation (THG), while dynamic control of impoundment operation is implemented during the post-flood sub-season. A fivereservoir system in the Yangtze River basin was selected as a case study. The results illustrate that (1) our developed framework can offer decision-makers a balanced trade-off between FCR and THG; and (2) the optimal THG solution achieve a 3.16 % increase in hydropower generation with little increase in FCR compared to standard operating policy, while also delivering enhanced performance across other operational metrics, including impoundment efficiency. These insights are valuable for decision-makers in the Yangtze River basin and highlight the potential of dynamic control strategies for high-capacity reservoirs in other regions.