Equal proportion flood retention strategy for the leading multireservoir system in upper Yangtze River

Eleven large reservoirs located on the upper Yangtze River were selected and constituted a watershed-scale multireservoir flood control system with the Three Gorges Reservoir (TGR) playing a key role. To overcome drawbacks of the present heuristic flood release rules for individual reservoirs, an improved Equal Proportion Flood Retention (EPFR) strategy with its clear implementation procedure was proposed. Two simulation models were developed: (i) Model I represents the current strategy to simulate the system actual behavior; (ii) Model II involves the joint operation using the EPFR. Ten different shapes of design flood hydrographs were used for demonstration. Compared with the present strategy (Model I), the EPFR (Model II) can help cooperation reservoirs avoid the situation of storing floodwater ahead and make their flood storage capacity used adequately, simultaneously guarantee the flood prevention standard of Jingjiang reaches to 100-years and result in an obvious reduction (10.34% in average) of excess flood volume at Chenglingji.