Yangtze River – Three Gorges Dam | The Water Page

THE CONSTRUCTION PROJECT:Excavation: 102.6 million cubic meters of earth and stone (134 million cubic yards).Concrete: 27.2 million cubic meters (35.5 million cubic yards).Steel reinforcing bars: 354,000 tons.Dam height: 185 meters (607 feet).Dam length: 2,309 meters (1.4 miles) divided into three parts. In the center will be a 484-meter spillway section with 23 bottom outlets and 22 sluice gates. On the left and right of the spillway will be two giant power stations (see below).Timing: Phase 1 began in 1994 and ended in 1997 with the initial diversion of the Yangtze River. Phase 2 began in 1998 and is due to end in 2003 when the water level rises to 156 meters (511 feet) and the dam starts generating electricity. Phase 3 should end in 2009 when the water level reaches 175 meters (574 feet) and full power generation begins.THE DOWNSIDE CONSEQUENCES:Water pollution in the dammed Yangtze will double _ at least _ as the dam traps more than 50 types of pollutants from mines, factories and human settlements that were formerly flushed out to sea by the swift Yangtze currents.About 1,300 archaeological sites will be moved or flooded.Critics contend that the heavy silt in the river will form thick deposits near the upstream end of the dam, clogging the major river channels of the city of Chongqing. Facing Inundation: 632 square kilometers (244 square miles), 19 cities, 326 villages, including 27,000 hectares (66,700 acres) of farms and orchards.Facing resettlement: 1.1 million to 1.9 million people.THE FUTURE RESERVOIR:Average width: 1.1 kilometers (0.7 miles).Length: 600 kilometers (370 miles).Storage: 39.3 billion cubic meters of water (51.4 billion cubic yards).Water level: elevated 175 meters (574 feet) above Yangtze River surface.Runoff: 451 billion cubic meters (589 billion cubic yards) of Yangtze River water will flow into the reservoir annually.Silt: The muddy Yangtze will discharge 530 million tons of silt into the reservoir in a typical year.THE ELECTRICITY:Machinery: The two power stations flanking the dam’s central spillway will operate 26 of the world’s largest turbine generators, 700 megawatts each.Capacity: Total generating capacity will be 18,200 megawatts, or as much as big 18 nuclear power stations.Transmission: Fifteen 500,000-volt transmission lines will send electricity to Shanghai and elsewhere throughout East China, Central China and eastern Sichuan Province.Output: 84.7 billion kilowatt hours of electricity annually, equivalent to burning 40 million tons of coal.THE SHIPPING:Ship lock will consist of five locks, each 280 meters (918 feet) long and 35 meters (114 feet) wide, with a water depth of 5 meters (16.4 feet). Supposed to handle 10,000 ton barges.Ship lift will be a one-stage vertical lift capable of carrying a 3,000-ton passenger or cargo vessel.River shipping through central Yangtze estimated to increase from 10 million to 50 million tons annually, with transportation costs cut by 30-37 percent.THE FLOOD CONTROL:Dam sponsors say the reservoir’s 22.1 billion cubic meter (28.9 billion cubic yards) flood control storage capacity should lessen the frequency of big downstream floods from once every 10 years to once every 100 years.THE RANKINGS OF WORLD’S TEN LARGEST HYDROELECTRIC PROJECTS(in megawatts of installed generating capacity)Three Gorges, China: 18,200Itaipu, Brazil and Paraguay: 12,600Grand Coulee, United States (Washington State), 10,100Guri, Venezuela, 10,100Tucuruii, Brazil, 7,500Sayano-Shushensk, Russia, 6,400Krasnoyarsk, Russia, 6,100Corpus-Posadas, Argentina and Paraguay, 6,000LaGrande 2, Canada, 5,300Churchill Falls, Canada, 5,200