The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in Yiling District,Yichang, Hubei province, China. The Three Gorges Dam is the world’s largest power station in terms of installed capacity(22,500 MW). The dam is the largest operating hydroelectric facility in terms of annual energy generation, generating 83.7 TWh in 2013 and 98.8 TWh in 2014, while the annual energy generation of the Itaipú Dam in Brazil and Paraguay was 98.6 TWh in 2013 and 87.8 in 2014.
Being the world’s largest hydropower project, this dam has created many “Firsts” such as the
- Most efficient dam in flood control
- The most difficult construction work
- The largest migration project in the world.
CONSTRUCTION
The dam project is composed of the dam, the hydropower stations and the navigation facility. It measures 607 feet tall and the top is 3,319 yards wide. It has taken 17 years to finish the construction of the whole project, which started in 1992 and includes three stages.
- The first stage took five years from 1992 to 1997. During this period, the cofferdam construction and the excavation of a diversion channel in the first stage were finished. Meanwhile, a temporary ship lock on the left bank of the river and some preparation work was also completed.
- The second stage lasted six years from 1998 to 2003, was undertaken at the same time as the construction of the permanent ship lock and the navigation buildings. The power station facilities construction and the installation of machinery on the left bank were also completed.
- The third stage of the project began in 2003 and has been completed in 2009. During this period, the installation of all machinery, the construction of the power station and the dam on the right bank are finished. Now, a 3,861 square miles canyon-reservoir dam is presented to the world.
Layout of Three Gorges Dam
Spillway
The Three Gorges Project is designed with a concrete gravity dam with a crest elevation of 185 meters and maximum height of 175 meters. The dam axis runs 2, 309. 47 meters long, which is even longer than the noted Grand Coulee Dam of US.
- The 483-meter spillway, located in the middle of the main dam, has 23 bottom outlets dimensioned at 79 meters. Each of its 22 surface sluice gates measures 8 meters wide. The maximum discharge capacity of the TGP is 116,000 cubic meters, the biggest in the world.
- Left Powerhouse Two powerhouses, flanking the spillway, accommodate altogether 26 sets of turbine-generators. As the world’s biggest unit ever made, each has a generating capacity of 700MW. The 643.6-meter-long left powerhouse, 60 meters longer than the 584.2-meter-long right one, houses 14 sets of generators. With all these huge generators, the TGP is designed to generate electricity of 84.7 TW/h.
BENEFITS OF THREE GORGES DAM
POWER GENERATION Hydropower is clean energy and environmental friendly. The operation of the Three Gorges hydropower station can reduce the emissions of ten million tons of carbon dioxide, one to two million tons of sulfur dioxide, 300,000 to 400,000 tons of oxynitride, 10,000 tons of carbon monoxide and 150,000 tons of dust.The total capacity of the Three Gorges Dam Project is 18.2 million kilowatts and the annual power generation is 84.7 billion kilowatt hours, which greatly relieves the electricity pressure in middle and eastern China. NAVIGATION
Located in the middle reach of Yangtze River, the Three Gorges Dam will largely improve the waterway conditions from Yichang City to Chongqing City. In the dry season, the water in the lower reaches of Gezhouba Water Control Project can get ample supply, and the navigation in the upper and middle reaches of Yangtze River will be well developed. TOURISM After the completion of the dam project, visitors will be delighted to see a wonder in the Yangtze River where a calm lake sits among the steep gorges
PROBLEMS CAUSED BY GORGES DAM
SEDIMENT PROBLEM
Sediment problem is always a heavy emphasis on the discussion of the Three Gorges Project. It is measured that the river sediment concentration of the upper stream is about 1.2kg per cubic meter. The total sediment passing the dam site is above five hundred million a year. Before the dam project, the mud and sand deposited largely in Jingjiang River, which has lifted the water level and menaced the safety of Jianghan (Yangtze River and Hanjiang River) Plain and Dongting Lake Plain ENVIRONMENTAL PROBLEM The Three Gorges Project has a great influence on the environment and ecology of the reservoir area and the Yangtze River. The biggest concern is the pollution of the reservoir. After the water storage, due to the steady state of the fluent, the contaminant cannot down rush in time and store up in the reservoir, which would deteriorate water quality and cause refuse floating, and probably trigger the epidemic. At present, some towns have started collecting potable water in other area, and while a great number of migrants are opening up the wasteland, the soil erosion and water pollution are growing in intensity. MIGRATION PROBLEM Migration problem is the biggest difficult point of the Three Gorges Dam Project. The fund for migration covers 45% of the total investment. After the water storage, about 129 cities and towns including Wanxian and Fuling are flooded. The migrants surpass 1200,000, relating to 20 cities and counties in Hubei and Chongqing. They were allocated to Hubei (outside the reservoir area), Chongqing (outside the reservoir area), Anhui, Hunan, Sichuan, Jiangxi, Jiangsu, Zhejiang, Shanghai, Fujian and Guangdong provinces to make a living. LANDSCAPE LOSS the water storage of the Three Gorges Dam, the rising Yangtze River has flooded a part of the landscape. Scenery changes a lot compared before the dam construction. According to a survey, the flooded natural scenery includes Military Books and Precious Sword Gorge, Dragon Gate Gorge, Ox Liver and Horse Lung Gorge, Hanging Monk Rock, Bayan Gorge, Guandao Gorge, Water Curtain Cave and Phoenix Spring. The flooded cultural sights include Quyuan Temple, White Crane Ridge, Daxi Culture, Zhangfei Temple, Dachang ancient city, Fengjie ancient city, Kongming Tablet, Chalk Wall, Mengliang Stairway, Dragon Backbone Stone and Qutang Gorge ancient plank road. The partly submerged natural landscape includes Bawu Gorge, Dicui Gorge, Wu Gorge, Qutang Gorge, Kongdong Gorge and Luyou Cave.
FOR VIDEO SHOWING THE CONSTRUCTION CLICK HERE
CIVIL ENGINEERING 
