Flood resource utilization of cascade hydropower stations along the Han River, China, based on a multi-scenario water level drawdown method

Han River, the longest tributary of the Yangtze River, China. In the dual context of global energy shortages and carbon reduction, increasing the share of clean energy in the power supply is imperative. Hydropower, as a crucial component of renewable energy, often sees its significant potential for power generation during flood periods overlooked. This study aims to enhance the joint power generation of cascade hydropower stations under different typical flood scenarios. Firstly, a multi-scenario water level drawdown method is proposed, providing strong technical support for hydropower stations to utilize flood resources and generate more clean power. Then, typical flood scenarios are selected that take into account the relationship between the basin's flood characteristics and the critical flows specified in reservoir flood dispatch regulations. Further, a flood resource utilization scheduling framework is developed to investigate the joint power generation benefit of cascade hydropower stations adopting different credible forecast times under various operational periods. The multi-scenario water level drawdown method can timely lower the reservoir level to the flood control level. Longer credible forecast times don’t always result in better performance, and the appropriate credible forecast time should be selected based on different inflow scenarios to maximize power generation. Through the flood resource utilization scheduling framework, the joint power generation benefit of cascade hydropower stations has increased significantly for 7–1–1 (38.96 *10 4 kW·h), 8–3–1 (145.18 *10 4 kW·h) and 12–1–1 types flood (351.38 *10 4 kW·h). • A flood resource utilization framework of cascade hydropower stations. • The optimal credible forecast time that maximizes the joint power generation. • A new reservoir water level drawdown method suitable for various inflow scenarios. • Typical flood scenarios considering reservoir dispatch regulations are selected.