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Three Gorges Project (TGP)


China Yangtze Three Gorges Project (TGP), as one of the biggest hydropower-complex project in the world, ranks as the key project for improvement and development of Yangtze River. The dam is located in the areas of Xilingxia gorge, one of the three gorges of the river, which will control a drainage area of 1 million km 2 , with an average annual runoff of 451 billion m3 . The open valley at the dam site, with hard and complete granite as the bedrock, has provided the favorable topographical and geological conditions for dam construction.

Map of Yangtze Basin

Although the TGP Reservoir is not the reservoir with the biggest capacity in the world, its reserved flood control capacity can help cut flood peak by 27,000 ~ 33,000 m3/s, the biggest for a water conservancy project in the world.

When the TGP is completed, the flood control standard of the middle and lower reaches of the Yangtze, especially the Jingjiang Section, will be largely upgraded from the present level of preventing under-10-year floods to that of preventing 100-year floods. So 15 million people and 1.5 million hectares of farmland in the Jianghan Plain are relieved from flood threats, and devastating plagues of massive death caused by big floods are avoided.

Floods records of Yangtze River (1931, 1935, 1949, 1954, and 1998)
1931....
The flood in 1931 struck an area of 130,000 km2 with 3.39 million ha farmland and 1.8 million houses inundated, 28.55 million people affected, and 145,000 people killed, causing approximately an economic loss of 1.345 billion YinYuan.
1935....
The flood in 1935 hit an area of 89,000 km2 in the middle and lower reaches of the Yangtze River, with six provinces, Hubei, Hunan, Jiangxi, Anhui, Jiangsu, Zhejiang and 10 million people affected, 1.51 million ha of farmland inundated, 142,000 people killed, causing approximately an economic loss of 0.355 billion YinYuan.
1949.... The flood in 1949 inundated 1.81 million ha farmland, affected 8.1 million people and cost the lives of 5699 people in the middle and lower reaches of the Yangtze River.
1954....
The damages caused by the flood in 1954 in the middle and lower reaches: totally 3.18 million ha farmland and 4.27 million houses inundated, 18.884 million people and 123 counties and cities affected, 33169 people killed and the interruption of the Beijing-Guangzhou Railway for 100 days.
1998....
The flood in 1998 struck a large area of the Yangtze Valley. The country went all out to fight against the flood for nearly 3 months with large quantities of people and materials employed. More than RMB 13 billion worth of flood-fighting materials were dispatched from all around the country, and about 6.7 million people and hundred thousands of soldiers took part in the fighting. However, the flood still caused great losses with 239,000 ha farmland inundated, 2.316 million people affected and 1526 people killed in the four provinces of Hunan, Hubei, Jiangxi and Anhui.

Biggest Flood Control Benefit in the World

Although the TGP Reservoir is not the reservoir with the biggest capacity in the world, its reserved flood control capacity can help cut flood peak by 27,000 ~ 33,000 m3/s, the biggest for a water conservancy project in the world.

When the TGP is completed, the flood control standard of the middle and lower reaches of the Yangtze, especially the Jingjiang Section, will be largely upgraded from the present level of preventing under-10-year floods to that of preventing 100-year floods. So 15 million people and 1.5 million hectares of farmland in the Jianghan Plain are relieved from flood threats, and devastating plagues of massive death caused by big floods are avoided.

Remarkable Navigation Benefit
Backwater of the TGP reservoir goes as far as to the southwest metropolis Chongqing, therefore it improves 660 km waterway, and largely enables 10000-tonnage fleets to navigate between Shanghai and Chongqing. The annual one-way navigation capacity of the Yangtze at the dam will be upgraded from ten million tons to fifty million tons.

Comprehensive Project Construction of the Biggest Scale
The construction of the main body of the Three Gorges Water Conservancy Complex includes the following work: rock-and-earth excavation of 102.83 million m 3 , concrete placement of 27.94 million m 3 , rock-and-earth refill of 31.98 million m 3 , metal frame installation of 256500 tons, installation of twenty-six 700 MW turbine-generator units (not including the six 700MW units in the Right Bank Underground Powerhouse under construction), and etc. Except the index of rock-and-earth refill, all the preceding indices are the biggest among water conservancy projects which are already built or under construction.

Its Buildings with Biggest Indices
  Dam
The TGP dam is a concrete gravity one, made of 14.86 million m3 concrete, the biggest amount in the world. The maximum flood discharge capacity of the dam is 116 ,110 m3/s, biggest in the world.
 Power Plant
The TGHP is of dam toe power house. The installed capacity of a unit and annual power generation of the TGHP are the biggest respectively. The transmission lines of two ±500 kV DC circuits and eleven 500 kV AC circuits are the biggest scale in the world.
 Three Gorges ship lock
The following indices are the biggest in the world: total water head of 113 m, inland river ship lock of five stages, a lock chamber's effective dimension of 280 m×34 m×5 m (length × width × minimum water depth on the sill), inland river ship lock with capacity to accommodate 10000-tonnage fleets, maximum operating water head 49.5 m for a gate of its water exchange system, maximum water fill/discharge amount of 260000 m 3 , maximum side slope excavation of 170 m, in height and etc. The operating water head exceeds the world record.
 Ship lift
Single-way and one-step vertical ship lift with counterweight is employed in TGP complex, consisting of upstream and downstream approach channels, upper and lower lock heads and ship chamber section with a total length of about 6000 m. The ship lock will allow a maximum 3000-tonnage ship passing through. The ship chamber has outline dimensions of 132 m (L) × 23.4 m (W) × 10 m (H) and effective water area in it is 120 m (L) × 18 m (W) × 3.5 m (D). The maximum lifting height is 113 m and total lifting weight about 12800 tons.
Compared with the ship lifts home and abroad that are built or under construction, TGP's ship loft ranks the first in the world in terms of the main technical parameters. Due to the large scale of construction, complicated operating conditions and high requirements in safety and reliability, TGP's ship lift also ranks the first among the world's ones built or under construction in terms of design, manufacture and difficult extent in construction.

Metal Works with Biggest Indices

The TGP metal works include 386 gates of various kinds, 139 hoists of various kinds, 26 penstocks, all of which add up to about 256500 tons. The overall work quantity ranks the top among the world's hydraulic projects built or under construction.

The following indices are also the biggest in the world: the penstock's inner diameter of 12.4 m, the maximum height of ship lock miter gate of 38.25 m, and operating water head of 36.25 m, single gate's weight of 850 tons.

The Relocation Population and Difficulty of Resettlement
According to a 1992 survey, the TGP reservoir impoundment will inundate 632 km 2 of land, including 24500 ha of farmland and citrus land, and affect habitats of 844100 people under submergence. It was planned to relocate a population of 1.13 million people. The relocation and resettlement of TGP reservoir migrants is a world record in scale and in difficulty.