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 Reservoir Region narrow and where the geography is complex. The mountainous areas represent 74% of the region only with 4.3% plain area in the river valley and 21.7% hilly area. The climate of the reservoir region of the Three Gorges Project is the subtropical monsoon climate. Its location is in the transfer between the northern temperate zone and the subtropical zone, where it is hot and it rains a lot with the annual rainfall of about 1100 mm. The valley of the Three Gorges Reservoir Region below 500 m has an annual temperature 17–19 °C and, with the frost-free period annually lasts