(June 22, 2012) The threat of geological disaster in the Three Gorges Dam reservoir area has prompted authorities to call on outside experts for help.

By Patricia Adams for Probe International

The German engineering and consulting company, DMT, has announced it has been called in to investigate the causes behind the environmental risks associated with China’s Three Gorges Dam.

A year ago, China’s State Council, the country’s de facto cabinet, admitted that the dam, the world’s largest, had caused many serious problems that needed to be addressed urgently.

Chief among these urgent problems is the threat of landslides: some 5,000 sites around the reservoir have been deemed “potential danger sites” by geological authorities. The concern is that large masses of earth could slide into the reservoir and sweep people and their property to the bottom of the dam’s 660 km long, man-made lake, and might even trigger tsunamis. One deadly slide in the Three Gorges area in 2003 was responsible for killing 10 people. Two others in 2008 forced the suspension of shipping in the area and created waves that violently rocked and displaced boats.

For this reason, the Sino-German project, which is being supported financially by Germany’s Federal Ministry of Education, will examine the effects of land-use changes, erosion, and substances infiltrating water in the reservoir area and, perhaps most urgently, the movement of geological masses.

Landslides are known to be triggered by changes in reservoir levels. In the flood season, the Three Gorges reservoir is lowered to accommodate floodwaters, and in the dry season, water is reserved behind the dam to generate power. The difference between the dam’s maximum and minimum levels of water is significant and can amount to 30 metres. The impact of such dramatic and constant change is to soften and destabilize the sloping sides of the massive dam’s reservoir.

According to a recent report by Caixin Online, 254 incidents of collapsing riverbanks and 235 landslides between 2008 – when the water surface reached its maximum level of 175 meters above sea level, and 2011, were recorded by the Changjiang Water Resources Commission. Thousands of homes and about 13,800 people were affected, although no deaths were reported.

The phenomenon of reservoir-induced landslides was well known before the dam project began, but the extent of danger was discounted.

Now that the threat has become real, the Chinese government is mobilizing to address it. According to DMT’s press release, their primary assignment will be to monitor and study the potential hazards in the affected area resulting from seasonal fluctuations. To that end, DMT will employ its own state-of-the-art equipment – including a cutting-edge “Summit II Vipa” seismograph and “DMT Safeguard” software package – for the early detection and monitoring of geological risks.

To read DMT’s press release about their study click here.

Additional reading on landslides at Three Gorges

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