Dam Burst Feared After Qinghai Earthquake, China

On April 14, 2010, an earthquake measuring at 7.1 (6.9 according to the US Geological Survey) struck Yushu County in the largely Tibetan area of Qinhai Province. The tremor, whose epicenter lies near the high mountain town of Jiegu in Yushu County on the Qinghai Plateau, killed 1,700 people and seriously injured 11,000.

The earthquake has highlighted civil society's concerns regarding dam safety and earthquake-related dam bursts. According to Chinese news reports, the Changu (or Thrangu in Tibetan) hydropower dam was damaged by the earthquake, and is "at the risk of collapse at any time." The Changu (Thrangu) Project is located upstream of the county seat, Jiegu, and is clearly visible on Google Maps. If the dam breaks, it would endanger the lives of more than 100,000 people living downstream.

Yushu County, on the upper reaches of the Yangtze River, is a hotbed of planned dam building in China. As we know from more than 100 documented cases around the world, high dams can trigger earthquakes. There is strong evidence linking the devastating Sichuan earthquake of May 2008 to the Zipingpu Dam. There is no evidence that the latest quake is linked to dam building in the area. However, the serious seismic risks call for utmost caution in building further high dams in western China.

Dams on the upper Yangtze, Mekong, and Salween rivers. (Tashi Tsering, http://tibetanplateau.blogspot.com)

Several very large dams are currently being built on the middle reaches of the Yangtze, downstream of Yushu County. There are also plans to build at least 81 large dams on the upper reaches of the Yangtze, the Mekong and the Salween rivers in Qinghai Province and Tibetan Autonomous Region. Two hydropower projects – Nieqiahe and Lagong – have already been built on the Upper Yangtze in Yushu County. Eleven more hydropower projects are under active consideration on the same stretch of the river. In addition, the 302-meter-high Tongjia Dam is being considered as the starting point of the Western route of the South North Water Transfer scheme in Yushu County.

China's older dams have a very bad safety record. Between 1954 and 2003, 3,484 of the country's 85,300 dams collapsed. China's dam critic Fan Xiao warns that the country's "poorly built and dangerous reservoirs are time bombs waiting to explode in the event of a severe flood or other unexpected occurrence". New dams, such as those planned on the Upper Yangtze, can be built to withstand very strong earthquakes. However, the homes, offices and public buildings in their vicinity are not built to the same safety standard. They can be severely affected by earthquakes triggered by dams and by the overtopping of reservoirs.

Given the experience with earthquakes and dams, high dams in seismically active regions such as Southwestern China should only be built if (1) the seismicity around the dam sites is continuously monitored, (2) water levels are not allowed to fluctuate quickly, and (3) all buildings in the reservoir areas are seismically retrofitted before the reservoirs begin filling. As Chinese geologists have informed International Rivers, none of these conditions are currently fulfilled in Chinese dam projects.