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Exclusive: Dam's flood capacity 'limited'
By Hu Yinan
Published: Jul 23 2010 9:21
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Cao Guangjing, chairman of the China Three Gorges Corp.

BEIJING — The flood control capacity of the Three Gorges Dam, the world's largest hydropower project, is designed to be limited, a senior engineer said on Thursday amid mounting concerns over the project's ability to manage floods.

The multi-billion dollar dam was designed to withstand floods with water flow of 83,700 cubic meters per second, covering the Jingjiang River area and the Chenglingji region in Hubei and Hunan provinces, Zhao Yunfa, deputy director of the China Three Gorges Corp's cascade dispatch center, told China Daily.

"The dam's flood-control capacity is not unlimited … it has a capacity of 22.1 billion cu m and protects, by design, a limited area … any flood with water flow exceeding 122,000 cu m per second would put the dam's own safety at risk," he said.

As China's main reservoir on the Yangtze River, the dam on Tuesday passed its first and largest test by sustaining a water flow greater than the flood of 1998, which killed 4,150 people across the country.

The flow of water into the dam's reservoir peaked at about 70,000 cu m per second. The dam, which was completed in 2008, discharged water at about 40,000 cu m per second.

Zhao's explanation came amid growing concern over the controversial dam, which officials hope would play a pillar role in flood control and clean power generation.

In the past few days, members of the public have been hotly debating online posts comparing four reports of the dam's flood-control capacity.

The first, released in June 2003, claimed that the dam "could fend off the worst flood in 10,000 years". The second, dated four years later, changed that number to "the worst flood in 1,000 years". In October 2008, the number was again modified to "the worst flood in 100 years."

On Tuesday, a report on State broadcaster China Central Television's website was titled "The Three Gorges Dam's capacity to store floodwater is limited". The story urged the public not to "lay all hopes on the dam".

In an exclusive interview with China Daily that same day, China Three Gorges Corp's chairman Cao Guangjing said he can "absolutely guarantee" that the dam is capable of withstanding "the worst flood in 100 years".

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