The researchers studied how the Zhangfeng Reservoir affects the design flood of the Hekoucun Reservoir. They found that when both reservoirs have the same flood frequency, Zhangfeng can increase the design flood volume at Hekoucun. During 100-year and 50-year floods, Zhangfeng can reduce the inflow flood volume by 4% and 1% respectively. When Wulongkou and Zhang-Wu reach have the same frequency, Zhangfeng can lower the peak flood at Hekoucun without affecting the 3-day and 5-day flood volumes.