Monsoon Rains Testing the Limits of China’s Three Gorges Dam

Water levels at China’s giant Three Gorges Dam on the Yangtze river are inching closer to their maximum after torrential monsoon rains raised inflows to a record high.

With 75,000 cubic meters per second of water flowing in from the Yangtze river on Thursday, the reservoir’s depth reached 165.6 meters by Friday morning. Up more than two meters overnight and almost 20 meters above the official warning level. The maximum designed depth of China’s largest reservoir is 175 meters.

The flow of water into the reservoir has shattered the previous record of 61,000 cubic meters per second set just last month. This is according to a statement from the Ministry of Water Resources.

Authorities raised the discharge volume to a record 48,800 cubic meters per second on Thursday. Above all to try to lower water levels, and they might have to increase it again to avoid the possibility of a dangerous overflow.

Since the floods began in June, officials have repeatedly offered reassurances that the dam could withstand what has been called once-in-a-century flooding. Some reports in state media have gone further, claiming that the dam had almost certainly prevented even worse flooding in major cities downstream. Including Wuhan, where the Covid-19 pandemic began.

Rains have Filled Three Gorges Dam Reservoir

On Friday, officials announced that the flow into the Three Gorges dam had eased somewhat. However they remained on alert. “They will do everything they can to prevent the dam from over topping,” said Desiree Tullos, a professor at Oregon State University who studies the Three Gorges dam project.

“An over topping dam is a worst-case scenario because it produces significant damage. The torrential monsoon rains can lead to the entire thing collapsing.” Rainfall in the Yangtze basin has been well over double the seasonal average this year. The floods had caused nearly 180 billion yuan (US$26 billion) in economic damages by last week. Also 63 million people have been affected.

The Three Gorges dam project, completed in 2012, was designed not only to generate power but also to tame the fierce Yangtze, the cause of many devastating floods throughout China’s history.

China’s giant hydroelectric dams have stored more than 100 billion cubic meters of floodwater this year, and shielded 18.5 million residents from evacuation, according to government figures. The Three Gorges project alone has cut downstream floodwaters by 34%, officials said.

But opponents say the flood control capability of the Three Gorges Dam is limited, and it could even make the problem worse in the long term.

Source: Reuters, AFP