|The Yangtze River in China is the World’s third longest river. In 1997, that country began work on what will eventually be the world’s largest dam and largest concrete structure, when it is finished in 2009. The Three Gorges Dam, in Hubei province, is a massive undertaking, as you will soon see.|
The dam will be built across the 3 Gorges section of the Yangtze River. It will be 600 feet high, and a staggering 1.2 miles wide. Requiring 12 years and tens of thousands of workers to build it, the dam will cost $29 billion, and will create a 370 mile long lake, requiring the flooding of thousands of villages, and hundreds of towns and cities, and displacing over one million people.
The Yangtze River, near 3 Gorges, before construction began
The Yangtze is a huge river. At 3700 miles in length, it apparently disgorges enough water into the Yellow Sea each year to cover the United States to a depth of one foot! Only the Nile and the Amazon rivers are longer than the Yangtze. The river not only moves a lot of water, but is also very unpredictable; its height varies considerably from season to season, and there is frequent flooding along its banks. About 400 million people live along its banks; over the years, millions of them have had their homes destroyed by flooding, and many thousands have died. Millions of acres of crops have been destroyed.
The 3 Gorges dam is needed to help control the level of the river downstream, so that flooding will no longer be a problem. It is also going to be a major source of electrical power for China, producing 18,000 megawatts, or the output equivalent to about 15 nuclear power plants!
However, the project has had some big hurdles to overcome. 1,000-year-old stone inscriptions have had to be removed from riverbank walls, and relocated to higher ground. But more importantly, between one and two million people will need to be relocated, before the reservoir fills and floods their towns and villages.
Construction has already begun on new villages.
The river will rise to between 135 and 185 metres at this location, rising to
the level shown, just under the level of the bridge (which will be demolished).
This town will be completely submerged.
The city of Wushan; the water level will be up to the red line.
After the dam itself is completed in late 2003, the level of the river behind the dam will begin to rise. Ships will start to use the lock system, to bypass the dam, and power will be generated as portions of the power plant are completed.
The first step, however, was to build a cofferdam from rock and dirt, to temporarily divert the river around the construction site. This was completed in 1997. (picture at left). Factories were built on-site, to prepare the steel and concrete. A new channel including ship locks, for ships to get past the dam, was also constructed. The Three Gorges Dam will have a pair of locks capable of raising 10,000-ton ships up from the river to the reservoir. (constructing the locks, at right)
What remains is the completion of the dam (it is already higher than the cranes used to lift materials), and the construction of the power generating station. The cofferdam came down in early 2002. Flooding of the reservoir will begin in 2003. Meanwhile, buildings in towns and cities where the reservoir will be , including a thermal power plant, government offices, and apartments, are being demolished to clear the waterway for safe passage of ships after the area is flooded. Water levels are set to rise up to 175 metres.
By 2009, 115 towns, 4,500 villages, 4,000 hospitals and clinics, 40,000 tombs, 100 bridges and 2.87 million tonnes of garbage will be submerged. 1,087 ancient relics are to be moved.
There is also concern that the giant lake will become a cesspool, as one billion tons of industrial and human waste are projected to flow into the reservoir. At least 30 million tons of industrial solid waste have already piled up on the banks of the river. The dam will prevent pollutants from being flushed to the sea, and funds have yet to be allocated for waste treatment.
However, officials state that China plans to spend nearly $4.8 billion to prevent pollution, with a 10-year plan that includes building more than 260 waste-water treatment plants and 200 garbage treatment facilities. Facilities will also be built to collect waste from ships and 42 ecological protection projects will be carried out. The upper reaches of the Yangtze River will be widely reforested.
‘Paper mills, fertilizer plants, wineries, mines, and other heavy polluters will be closed if they fail to meet the pollutant emission standards set by the state’, stated one official.
|3 Gorges Dam Facts: