Compromising power generation and flood control: Optimizing flood operating water levels in mega reservoirs

Optimizing the joint operation of adjustable flood operating water levels for mega reservoirs in flood seasons presents a significant opportunity to utilize floodwater potential, boost hydropower output, and mitigate carbon emissions. However, this task is highly complex due to uncertainties in dynamic flood forecasts and forecast accuracy, compounded by the intricate nature of hydraulic connections, storage adjustments, operational protocols, and flood prevention points in mixed mega reservoirs. This study introduces a novel multi-objective operation framework for flood operating water levels in mixed mega reservoirs, emphasizing hydropower generation and flood prevention. Seven mixed mega reservoirs within the Yangtze River Basin were investigated, using the standard operation policy as the baseline. Results demonstrate the effectiveness of the proposed method, showing prominent comprehensive benefits such as a 6% improvement in hydropower production, a 28.7% reduction in spillage, and a 6.1% decrease in carbon emissions under the maximal hydropower output scheme compared to the standard operation policy over the entire flood season. This study provides scientific and technical support for dynamically managing flood operating water levels in mixed mega reservoirs. Stakeholders and policymakers are furnished with pre-experienced operational strategies considering potential flood risks and advantages across dynamic flood forecast scenarios.