The Three Gorges Dam, China

The Three Gorges Dam is currently under construction in the Yangtze river and it will be the largest hydraulic project in the world. The project is located between the cities of Chongqing and Yichang (Hubei Province). Its construction began in 1993 and is expected to be completed in the year 2009. After 14 of the 17 years that the construction will last we can mention that the project is in its final phase.

The proposal for the construction of this dam dates none other than that in the year 1919, though its eventual adoption it has been delayed until 1992. The Three Gorges Dam will be the largest in the world, and it will overwhelm the Qutang, Wu [photo] and Xiling fluvial gorges, reaching nearly 200 kilometers long. The width of the gorge varies from 300 to less than 100 meters in the straightest area. The seasonality of rainfall in this region causes great changes in the water levels of these gorges. The reservoir produced by the dam will overwhelm over 250 km2 of land.

On the one hand it is seek to regulate the flow of the Yangtze river, avoiding the severe floods which occur frequently in the nearby of that river (the third longest river in the world). On the other hand, the dam will be used for power generation. It will have 26 turbines of 700,000 kW each, adding a total of 18.2 GW. The energy production could reach the 84,000 million kWh annually. Controlling the flow of the Yangtze River is an old aspiration of China, spurred mainly by the floods that sometimes have taken the lives of hundreds of thousands of people. The control of the river also enables a better use for its navigation, with the resulting economic impact.

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The concrete dam conforms to the type of gravity prey. The dam has 183 meters above ground and 2,310 meters long.

The constructions have been divided in three stages:

- 1st Stage (1993-1997): During this phase, it was built a temporary channel to divert river navigation while also beginning to build the first barrier containment of the waters. It was also built at this stage complementary infrastructures and endowments.

- 2nd Stage (1997-2003): The channel was cut provisionally, returning the waters to its natural river-bed so starting the accumulation of the waters. During this phase it began the installation of the first generation equipment, which started to produce electricity in 2003.

- 3rd Stage (2004-2009): During this phase they are completing the work of the massive concreting of the dam’s wall, because in the less sensitive areas there was only built the necessary structure to stand the early years of accumulation of water. It is also being installed the remaining generating sets.

Despite the enormous difficulties that were found during the process, the first 2 phases were completed on schedule, and the latest is in its projections, so the entire infrastructure will be ready by the target date of 2009.

As in any large project, not everything is progress and benefits. The construction of this infrastructure has huge environmental and social impacts of enormous characteristics. In the flooded fields are located sites of high ecological value, historic and prehistoric archaeological sites, as well as 15 cities and hundreds of small villages with a population of about 1,800,000 people who are being or have already been relocated, mostly in new neighborhoods built in the city of Chongqing. These kinds of impact are those that have generated more controversy around the project as well as other related to embezzlement.

Among the cultural property threatened by the reservoir there are more than 60 sites with relics of the Paleolithic Age and paleontological fossils, more than 80 sites of the Neolithic age, about 100 ancestral burials and over 450 significant tombs. There are also about 300 constructions of structures of imperial Ming and Qing Dynasties (1368-1911).

Among the threatened relics there are four classified as “State Treasures.” These four wonders are the town of Dachang (almost all the houses are between 300 and 400 years), the Zhang Fei Temple (1800 years old), the village of Shibao [right] (one of the most complex wooden structures in the world) and the inscriptions on Baiheliang hydrometric.

The Chinese government has opted for different options with respect to these historical treasures. Zhang Fei Temple will be moved completely including vegetation adjacent to a new location safe from the waters. Shibao village will be surrounded by a dike with a pier, leaving an island visited within the reservoir. In the case of Baiheliang and Dachang the authorities have chosen to build replicas in the vicinity, so that the original buildings won’t be saved from the flooding.

About to the environmental problems we are faced with the accumulation of sludge, because landslides are common in the region due to the rains. The sludge would be present at the reservoir, which retain the natural flow of the river would prevent the auto cleaning of these sediments, drastically worsening the quality of the water. Chinese technicians have been working on a system to avoid this problem and apparently have developed a method to reduce partly of its impact, which has been tried effectively in other large dams in the country. The dam carries therefore a decline in the quality of the water and in addition the disappearance of much of the landscape and vegetal mass in the area.

But, without doubt, the worst is for the native fauna, where we can find the Chinese dolphin, a river dolphin species which is estimated to be less than 100 copies at the moment, and the Chinese sturgeon, a true living fossil that has been living since 200 million years ago. Many other species would be severely affected by the tremendous changes in ecosystems that leads the project.

Despite all the problems and controversies, the dam has been carried out and is now close to its completion. In less than 3 years, will be completed this huge engineering project named by some as the “second Chinese wall”.