Three Gorges Dam dam. An important function of the dam is to control flooding, which is a major problem for the seasonal river of the Yangtze. Millions of people live downstream of the dam, with many large, important cities like Wuhan, Nanjing, and Shanghai situated adjacent to the river. Plenty of farm land and China's most important industrial area are built beside the river. The reservoir's flood storage capacity is . This capacity will reduce the frequency of major downstream flooding from once every ten years to once every 100 years. The dam is expected to minimize the effect of even a "super"
Three Gorges Dam tonnes each and are designed to produce more than 700 MW of power. The designed head of the generator is . The flow rate varies between depending on the head available. The greater the head, the less water needed to reach full power. Three Gorges uses Francis turbines. Turbine diameter is 9.7/10.4 m (VGS design/Alstom's design) and rotation speed is 75 revolutions per minute. This means that in order to generate power at 50Hz, the generator rotors have 80 poles. Rated power is 778 MVA, with a maximum of 840 MVA and a power factor of 0.9. The generator produces