Dams and Landslides

Three Gorges landslide threat forces villagers to flee

Sutton Eaves
Three Gorges Probe
May 9, 2007

Nearly 100 villagers living upstream from the Three Gorges dam have been forced to leave their homes under threat of a landslide, which officials fear was disturbed during the filling of the dam’s reservoir last year, Xinhua News Agency reported this week.

The Yemaomian (wild cat face) landslide is 17 kilometres upstream of the Three Gorges dam in Hubei province’s Zigui county. Chinese experts identified the old landslide as unstable and prone to collapse in 2003, when the filling of the Three Gorges reservoir began. As predicted, several slides have forced residents to flee their homes since then.

Fears were raised again last month when residents of Miaohe village discovered a 200-metre fissure in the Yemaomian landslide. This week, 99 villagers from 22 households were evacuated as a precautionary measure in case the landslide, which carries an estimated 12 million cubic metres of rock and earth, drops into the Yangtze river.

Although the cause of the crack is still unclear, no major rainstorms or any significant changes in the GPS monitoring network have been recorded in the reservoir area. But a preliminary investigation cited by one local official suggests the crack was prompted by water level fluctuations in the reservoir.

“According to local people, the crack on the Yemaomian slide was caused by the fluctuation of water levels after the reservoir was filled to 156 metres last October,” Cheng Chongjun, director of the Three Gorges area administration of the Yangtze and Three Gorges Navigation Administrative Bureau, told Xinhua. “Our preliminary investigations reveal that the deformation of the slide is most likely related to these reservoir fluctuations.”

Zhao Zongzheng, a county official, said he fears that the deformation could worsen when the reservoir is lowered to 144 metres in preparation for the approaching flood season. Although the crack is currently stable, heavy rainfall or unexpected seismic activity could trigger further deformation.

Three Gorges dam, the world’s biggest, was built in a geologically unstable area prone to landslides. In 2001, a survey by the Changjiang Water Resources Commission identified 1,320 zones in the area at risk of landslides. Senior water engineers warned that impounding a huge body of water in the 600-km-long reservoir could activate at least 760 landslips many of which have since broken loose in Hubei province and beyond.

The county government said that by the end of October, new houses will be built for the Miaohe evacuees on a flat area just two kilometres from the reactivated landslide. Xinhua did not report where the displaced villagers will live between now and then.

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