Impact upon Navigation Conditions of River Reach between the Two Dams by Peak Shaving at Three Gorges Hydropower Station

In order to give full play to peak shaving capacity of Three Gorges Hydropower Station and reduce impact upon shipping by peak shaving operation at Three Gorges Hydropower Station (TGHY), the paper carried out a preliminary research with a 1:110 physical model on mode of daily regulation during low-flow season and mode of peak shaving during flood season of the power station. The results of the study demonstrated that impact upon navigation due to unsteady flow generated in water course between the above-mentioned two dams by daily regulation at TGHS during low-flow season is limited because regulating flow quantity and regulating capacity is relatively small. But during flood season, both peak shaving amplitude and flow quantity fluctuation amplitude of TGHS are large. As a result, flow velocity, gradient ratio and water level fluctuation along river reach between the two dams increase dramatically during peak shaving process of the power station as compared with those during low-flow season. When average daily flow quantity and peaking capacity reaches or exceeds 20000m3/s and 8 million KW respectively, flow velocity and gradient ratio at key shoals of water course between the two dams exceed the allowable values for a 10,000-ton fleet. Therefore, sail of up-bound vessel becomes very difficult.