Dams and Landslides

China Three Gorges dam faces major flood test

(July 19, 2010) (Reuters) – China’s massive Three Gorges dam is facing a major test of the flood control function that was one of the key justifications for its construction, as torrential rains swell the rivers that feed it, state media said Monday.

Much of China has been suffering flooding and landslides after weeks of torrential downpours. At least 146 people have died since the start of this month, as a result of the rains, and another 40 are missing.

The peak flow of water hitting the giant reservoir on the Yangtze River, China’s longest, will be higher than in 1998 when devastating floods killed over 4,000 people and forced some 18 million to relocate, the official China Daily said.

Engineers have raised the rate at which water is being sluiced out of the reservoir, to make room for new waves of floodwaters expected this week.

“The levels of this flooding will be higher than the historic floods of 1954 and 1998,” Wei Shanzhong, Head of the Flood Control and Drought Administration office for the Yangtze River, told state Television.

“The rain in the gorges area will have an immediate affect on the water flow, to around 70,000 cubic meters (per second).”

Overall however, the flood this year is expected to be shorter than the 1998 disaster.

When the flood-tide hits, locks that allow shipping on the reservoir up to the city of Chongqing, a southwestern hub, will be closed if the water comes faster than 45,000 cubic meters per second, the China Daily report added.

The dam was given the go-ahead by the government in 1992, against unusually visible domestic opposition — with environmentalists warning the reservoir could turn into a cesspool of raw sewage and industrial chemicals trapped behind the dam, and feared silt could also cause problems.

The government justified its decision to push ahead by citing massive clean power generation and flood control were cited as the reasons it was pushed through. If it fails in the latter task it will add to concerns about the dam’s overall cost and impact.

However even if the dam succeeds in its role of holding back deadly floodwaters there may still be problems downstream where continuous rains have also weakened dikes. Further north at least 20 people are missing after a landslide last night in a mountainous corner of Shaanxi province, around 400 km (250 miles) from the provincial capital of Xian.

Altogether over 38 million people have been affected and over 1.3 million have had to be evacuated, because of the weather, the Ministry of Civil Affairs was quoted as saying by the China Daily.

Emma Graham-Harrison, Reuters, July 19, 2010

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