Construction completed on Three Gorges Dam

China: Demolition of the 580 m long protective cofferdam at the Three Gorges Dam site earlier this month marks completion of construction work on the controversial US$ 25 billion project. The 2.3 km long, 185 m high concrete gravity dam in the Hubei Province will now start to take the full strain of the Yangtze River for the first time, two years ahead of schedule.

Over 170 tonnes of explosives, split into 971 consecutive explosions set off over 12 seconds were used to demolish the 140 m tall cofferdam on 6 June. The temporary dam was built in 2003 to enable construction of the main dam to be completed and to generate electricity for the construction. Main contractor Three Gorges Project Corporation installed two layers of ‘bubble curtains' to the front of the cofferdam to prevent the shockwaves from the demolition from damaging the completed Three Gorges Dam which is located 114 m away.

More than 16 million tonnes of concrete has been used to construct the Three Gorges Dam and the final pour was completed on 20 May. Work on building the dam started in 1993 with the joint aim of controlling flooding on the Yangtze River and generating over 18000 MW of electricity per year when fully operational.

The dam is currently fitted with 26 turbines and a further six underground turbines will be added in 2009 but the hydroelectric generation will not reach capacity until the 660 km long reservoir is fully filled.

Navigation of the Yangtze River is provided by a two-way lock system which was opened in 2004 and will be replaced by a one step ship elevator, which is due to open in 2009.

Despite the dam's ability to provide electricity for over 28 million people and control previously catastrophic flooding, environmentalists claim that completion of the project has come at a high cost. According to reports in the local press, more than 100 workers were killed during the construction and over 1 million people have already been relocated and another 80000 will be moved as the reservoir reaches capacity.

Environmentalist claim that the water impounded by the dam is already heavily polluted and the construction has led to the loss of 632 km² of prime agricultural land. It is also claimed that the project's water treatment plants have failed to prevent stagnation and has led to the loss of several fish species from the river.