Abstract: Salt tide intrusion has always been an important factor of water supply safety in the Xijiang River Basin, and reasonable reservoir operation becomes a key measure to suppress saltwater and fill freshwater. This study develops a real-time optimal operation model for the cascade reservoirs in the Xijiang River basin to maximize both the cascade’s total power output and the lower limit of saltwater-suppressing flows, considering power generation benefits and the saltwater-suppression goal for the downstream Wuzhou section. The results show that the basin should increase power output mainly by raising the Yantan reservoir’s water stage and the risk of salt suppression, while the other reservoirs be responsible for reducing this risk and ensuring the saltwater-suppression flowrate. With the basin inflow at a frequency of 90%, a loss of 0.06% in the cascade power output leads to the suppressing flow to be increased up to 3163 m3/s at Wuzhou in operation period. With a 95% basin inflow, the power output will be increased by 330,000 kW·h, while the saltwater suppression guarantee level increased to a period of three days. The results reveal how the saltwater control risk to transfer between different reservoirs, enhancing water supply safety for the Pearl River delta and the Greater Bay area.

Key words: saltwater intrusion suppression, cascade reservoirs, multi-objective, optimal operation, risk