3 Gorges Dam “Deformed Slightly” after Heavy Rains

July 21, 2020

The Three Gorges dam is discharging flood. Yichang City, Hubei Province, China, July 2. The dam has come under new scrutiny after devastating flooding over the past few weeks.

“Deformed Slightly” is not what you want to hear about the plane you are flying on, or the world’s largest dam project.

Asia Times:

In a rare revelation, Beijing has admitted that its 2.4-kilometer Three Gorges Dam spanning the Yangtze River in Hubei province “deformed slightly” after record flooding.

The official Xinhua News Agency quoted the operator of the the world’s largest hydroelectric gravity dam as saying that some nonstructural, peripheral parts of the dam had buckled.

The dam was a pet project of the late Premier Li Peng and a monumental pride of the nation when it blocked and diverted Asia’s largest river in 1997. 

The deformation occurred last Saturday when the flood from western provinces including Sichuan and Chongqing along the upper reaches of the Yangtze River peaked at a record-setting 61,000 cubic meters per second, according to China Three Gorges Corporation, a state-owned enterprise that manages the dam and the sprawling power plant underneath it.

The company noted that parts of the dam had “deformed slightly,” displacing some external structures, and seepage into the main outlet walls had also been reported throughout the 18 hours on Saturday and Sunday when water was discharged though its outlets.

But the problem of water seeping out did not last long, as the dam reportedly deployed floodgates to hold as much water as possible in its 39.3 billion-cubic-meter reservoir to shield the cities downstream from the biggest Yangtze deluge so far this year. 

It is believed that the dam’s operator must protect the central megacity of Wuhan, whose 10 million residents are still reeling from the coronavirus pandemic that erupted there in December.

Xinhua also stressed in its report that all metrics were still up to standard and all the variables being monitored fell within the design parameters. 

Meanwhile, Wang Hao, a member of the Chinese Academy of Engineering and an authority on hydraulics who sits on the Ministry of Water Resources’ Yangtze River Administration Commission, has also assured that the dam is sound enough to withstand the impact from floods twice the mass flow rate recorded on Saturday. 

Still, Wang’s remarks stoked a volley of mockery after he said the flooding could be a good thing as the dam would only become more rigid the longer it was steeped up to its top.

Zhang Shuguang, director of the Three Gorges Corp’s Hub Management Bureau, echoed Wang’s judgement, saying nothing could topple the dam in the next 500 years and that not one of the 12,000 sensors fitted throughout the humongous concrete barrier had ever flashed red on the central control panel. 

Zhang added that the dam was constructed from concrete, whose cement reacts with the water to form a hard matrix binding blocks together into a durable form. Also, as a gravity dam, it was designed to hold back water by using the weight of the material alone to resist the horizontal pressure of water pushing against it, with ample structural redundancy built in. He said each section of the dam would remain stable and independent of any other section, even if the structural integrity of one portion was compromised. 

Still, he warned that flood control measures for the entire Yangtze River Basin could not rely on the Three Gorges Dam to control flooding as his paramount task would be to ensure its own safety. 

Flood control was one of the key merits touted by Li when he rammed the 95.5 billion yuan (US$13.5 billion) project through the National People’s Congress in 1994, although almost a third of its deputies abstained or voted against the project. 

Proponents of the mammoth project to harness the Yangtze stressed back then that the dam was designed to discharge and regulate floods of “cataclysmic” proportions that might only strike once in ten centuries, when concerns over the dam’s own safety during flooding almost scuppered the plan during deliberations by the Chinese parliament.

Nikkei Asian Review:

Torrential rains that typically hit in July and August started in the middle of June this year. Video clips on social media showed rivers overflowing and submerging homes, including a three-story home in Jiangxi that collapsed and was swept away by strong currents on July 5.

Economic losses from damage to properties in 13 provinces had reached 25.7 billion yuan ($3.6 billion) by the end of June, according to an estimate by PingAn Securities. Continued flooding is expected to drag down investment in the third quarter but unlikely to affect economic output as a whole, it said.

Residents in affected areas appeared to be more concerned that the Three Gorges Dam would breach its banks with further downpours, even though authorities had released floodwater from the dam upstream on June 29.

In one video posted by a resident in Wuhan on Friday on the Toutiao Jinri news app, Yangtze River’s water level reached 28.11 meters, well above the average, even though there had been no rain in the city in recent days. Wuhan is one of the cities in the Yangtze River basin, south of the Three Gorges dam.

Dam authorities tried to reassure residents by saying in state media on July 8 that the reservoir could still hold more rain as it had only reached 149 meters of a maximum of 175 meters that it can contain.

Like others, Zhang Jianping, an activist in Jiangsu, is skeptical.

“With hindsight, I think that all those experts who opposed the buildings of the Three Gorges were right,” Zhang said on Radio Free Asia. “Since it was built, it has never played a role in preventing flooding or droughts, like we thought it would back then.”

Despite protests by residents and environmentalists, the Three Gorges Dam was completed in 2006 after a 12-year build. Millions were displaced as an area of about 600 kilometers was submerged to create the world’s largest dam and hydroelectricity facilities.


10 Responses to “3 Gorges Dam “Deformed Slightly” after Heavy Rains”

  1. Gingerbaker Says:

    This reads like the opening chapter of a Michael Crichton novel.

  2. doldrom Says:

    All the commotion is sensationalism. The dam might be a failure environmentally and may fail at its main purpose sometimes (which is to control periodic flooding), apparently due to unprecedented amounts of moisture being wrung from the atmosphere. The real story here (besides the flood damage) is the atmosphere.

    But there is nothing to collapse. It’s like damming a stream by dropping a bunch of boulders side by side. As long as the boulders are heavy enough, they will stay put, even if you remove one. The dam consists of independent blocks, just sitting there, with some cement in the (relatively tiny) gaps.

    The billions of acre feet of water impounded upstream make no difference. The pressure on the dam would be exactly the same if you had built a wall of the same height 10 yards upstream and poured the ensuing room full of water. The horizontal water pressure is exactly proportional to the height of the water. A few feet extra will not matter, not even if it were to overtop the dam.

    The only things that can go wrong would be scouring of the foundations or the flood sluices. But of course the thing was built with sluicing of the impounded water in mind. Nobody seems worried that they cannot release enough water and that the dam will be overtopped. Even that would not cause worse flooding than if there were no dam. The other thing that could happen is the collapse of the canyon walls, but nobody is suggesting that either.

    In short, there is nothing to collapse, crumble, break, erode, fail, or wash away, etc.

    Stories about Taiwan using missiles to destroy the dam are fanciful. Perhaps a nuclear explosion to create a tsunami-like wave upstream might accomplish something.

    • rhymeswithgoalie Says:

      From 7/23 Nikkei Asian Review

      One of the world’s largest, the Three Gorges Dam in Hubei Province is now holding back water from the Yangtze River, China’s longest, at a level topping 162 meters as of Tuesday afternoon. The dam was built to hold 145 meters of water.

      It isn’t a completely static structure. The pounding flow through the sluices pretty much ensure that the entire structure is continuously vibrating, which would change not only the pressure on the dam itself, but be telegraphed through the surrounding geology. (The dam is less than 15 years old, so it’s possible all of the concrete hasn’t set yet, but they may be using more modern curing accelerants than I’m familiar with.)

      As far as the impound area, remember that much of the damage might not be the dam per se, but the result of the additional water pressure into rock faults, layers or crevices, that add lubrication for slippage (aka “mass wasting”), causing a major tsunami without a nuclear bomb.

      • doldrom Says:

        True. I did mention the canyon walls. But they are never mentioned in the stories (I’ve already seen about 30).

        Contrary to most people, I think the Chinese leadership does care about China (and saving their own asses), and would be making plans if convinced there was a threat. I know people assume that the world is full of deceit and Lysenko’s outside our own privileged corner of the globe, but there are good people elsewhere as well.

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  4. rhymeswithgoalie Says:

    As long as the boulders are heavy enough, they will stay put, even if you remove one.

    When I was taking geology classes 20 years ago (after I retired), one of the field trips was to a relatively small local Canyon Lake Dam which had overtopped its spillover—as designed—for the first time. What they didn’t expect was the water to crash through the karstic spillway and carry massive slabs of limestone (tablets > 1m thick) about 1km, covering the access road with rip-rap.

    • doldrom Says:

      Rushing water has momentum. Isostatic water pressure has none.

    • doldrom Says:

      Over time there can be changes. A sapling splite granite. But not every turbulent stream/wave will dislodge every stone mass. It depends on the forces that are brought to bear. I did mention a tsunami upstream.

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