(April 14, 2009) The threat of a massive landslide has prompted government authorities to issue an emergency warning to boat operators plying the Three Gorges reservoir, according to Chinese news sources.

Hundreds of boats carrying thousands of tourists pass by the landslide area every day, which is in the heart of the 600-kilometre long reservoir at Shuirang Village near Guling Town of Yunyang County.

The Liangshuijing slide , as it is known, measures 600 metres wide, 300 metres long, and an average of 20 metres high, with a total volume of 3.6 million cubic metres.

Fifty-five residents were evacuated last November, when a chunk of the landslide broke loose from the river bank after the reservoir was nearly filled to its final height of 175 metres. Since then the landslide has continued to move, prompting a team of geologists from the State Geological Survey Bureau to begin monitoring the slide around the clock.

According to China News Service (April 7), several government departments, including the State Geological Survey Bureau, are now on the scene trying to contain the slide.

Tourism authorities in Chongqing insist the reservoir is still safe, the coastguard boats have reported no casualties or injuries, and navigation remains normal.

Zhou Shihong, vice director of Chongqing Land Resources Bureau, is quoted by China News Service as saying the activation of the Liangshuijing landslide is the most dangerous incident to occur along the Chongqing section of theYangtze since the Three Gorges reservoir was filled late last year.

In fact, the dam operators started filling the reservoir to 175 metres last September, but stopped at 172 metres due to mounting concern over geological disasters in the area. The reservoir has since been lowered to around 160 metres, which officials say has reduced erosion of the river bank and the threat of more landslides.

Since the Yangtze was first dammed in 1997, the reservoir was to be filled in stages: first to 135 metres in 2003, second to 156 metres in 2006, and to its final height of 175 metres by September 2009.

Ying Yueping, deputy chief engineer of the SGSB, was quoted by China News Service saying the deformation of the landslide appears as an extended crack that is getting bigger but it would not block the waterway of the Yangtze [Three Gorges reservoir] and even if the slide occurs, it would have no impact on navigation.

Mr. Ying’s statement contradicts an earlier report by China News Service on April 5th, which said that the Liangshuijing slide would block part of the waterway should it fall into the reservoir and poses a serious threat to boats going up and down the reservoir.

Xinhua offers similarly contradictory statements from officials. A report from April 8th quotes an expert panel from the Ministry of Land and Resources saying that if the landslide does fall into the Yangtze, it could cause waves of 5 to 10 metres high within 3 to 5 kilometres of the slide. Other officials are quoted saying the river is safe but navigation would be banned in the event of heavy rain.

Caijing magazine (April 7) quotes an unnamed official with the Chongqing Land Resources Bureau saying that 150 geological disasters have been recorded in the Three Gorges reservoir area since the final stage of filling began last September. The incidents have affected more than 9,000 people to date, and caused economic losses amounting to US$49 million.

Geologists expect the landslide problem will only get worse now that the reservoir has been filled, according to an internal report by the Changjiang [Yangtze] Water Resources Commission under the Ministry of Water Resources, cited by Caijing.

The magazine also quotes an unnamed expert with the Changjiang Water Resources Commission explaining how the Three Gorges dam, originally built to help control floods downstream of the dam, has made flooding worse than ever along the reservoir shore upstream of the dam: According to the dam’s operating mode, the Three Gorges reservoir will be lowered to 145 metres each spring and then raised to 175 metres each fall. This 30-metre fluctuation in water level is very similar to what would be experienced during a flood of 100 year-frequency. In other words, such a huge fluctuation in water level would occur once every 100 years or so before the Three Gorges reservoir was filled. Now the 100-year flood happens every year.

Numerous Chinese experts warned the Three Gorges dam would increase flooding and trigger landslides upstream of the dam before the project was approved in 1992 but proponents dismissed the problem.

Grainne Ryder, Probe International, April 14, 2009