Record floods raise doubts about China’s Three Gorges Dam

SHANGHAI (Reuters) – As China calculates the costs of its harshest flood season in more than three decades, the role played by the controversial and massive Three Gorges dam, designed to help tame the Yangtze River, has come under fire. a new scrutiny.

Amid some of the heaviest rains on record, the Chinese government says the world’s largest hydroelectric plant has reduced flood peaks, minimized economic losses and reduced the number of deaths and emergency evacuations.

But critics say the historically high water levels in the Yangtze and its main lakes prove that the Three Gorges Dam is not doing what it was designed for.

“One of the main justifications for the Three Gorges Dam was flood control, but less than 20 years after its completion we have the highest flood water in recorded history,” said David Shankman, a geographer at the University from Alabama studying Chinese floods. “The fact is, you can’t prevent these severe events.”

Ye Jianchun, China’s vice minister for water resources, said in a briefing on Monday that “detailed scheduling” of water discharges from reservoirs, particularly the Three Gorges, had been effective in controlling flooding this year.

He said 64.7 billion cubic meters of flood water has been stored in 2,297 reservoirs, including 2.9 billion cubic meters in Three Gorges.

The company that runs the Three Gorges Project also said Saturday that downstream water discharges had been cut in half since July 6, “effectively reducing the speed and extent of water level in the middle and lower reaches. under the Yangtze. ” The total amount of stored flood water had now reached 88% of the total capacity of the reservoir, he added.

But parts of the Yangtze, its tributaries, and major lakes like Dongting and Poyang have reached record levels anyway.

Fan Xiao, a longtime Chinese geologist and critic of giant dam projects, said the storage capacity at Three Gorges amounts to less than 9% of the average flood water.

“It can only partially and temporarily intercept upstream floods, and cannot help with flooding caused by heavy rains in the middle and lower reaches of the Yangtze River,” he said.

Fan said Three Gorges and other major dam projects could even make flooding worse by altering the flow of sedimentation in the Yangtze. The project’s need to generate electricity has also undermined flood control, he said.

“When people only consider using reservoirs to solve flood control problems, they often overlook or even weaken the natural ability of rivers and their lakes to regulate flooding,” he said.

Shankman said the Three Gorges Dam helps alleviate flooding during normal years, but that it is always likely to be vulnerable to more extreme weather conditions, a problem compounded by the reduction of downstream flood plains.

“The Three Gorges Dam reservoir does not have the capacity to significantly affect the most severe flooding,” he said.

“Flood water storage along the Middle Yangtze is less due to stronger levees that are less likely to fail,” he added. “Both are at stake here. This was predictable. ”