Is China's 3 Gorges Dam Safe?

In this video, I discuss what we know about potential safety problems associated with the 3 Gorges Dam on the Yangtze River in China. To put the potential issues with this dam into context, I describe the main types of dam structures and what have been some notable dam failures.

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[larryscott]

There are several dams upstream from 3 Gorges which could fail and cause over topping. So 3G dam is dependent on several lesser older dams. And that’s the true hazard.

[bbokdoong]

The failure of the 3 Gorges dam could result in the failure of some 20 nuclear powerplants downstream.

[timkenyon]

Hydrogeologist here....1) the dam in Italy should be considered tt be a rather spectacular example of proper design and construction in that it survived the landslide-generated tsunami. That was not a failure of the dam, it was a failure to consult competent geologists on the ramifications of the reservoir (or to heed their input), which in my experience, is not unusual. 2) Considering the number of dams worldwide, even in the developing world, the relatively small number of failures (and the even smaller number of catastrophic failures) compared with number of dams suggests that dams are a very safe way to meet the needs of flood control, power generation and navigation.

[Odin]

I can tell you that its a weird feeling living at the mercy of a dam. Wolf Creek Dam in Kentucky sits on the Cumberland River and holds back the largest reservoir in the Eastern US. Well several years ago it started having very serious problems. They said that if that dam failed and the lake emptied that it would devastating all the way along the course of the river. Well I live not quite a mile from the Cumberland River, so it felt like this danger just hanging over my head that I could do nothing about. I can only imagine what's like in the cities down river from the Three Gorges Dam if there really are problems with it.

[Mrbfgray]

Visited Teton dam weeks after it failed. Surreal to be looking at the idealic "info-board", visitor overlook, with all the joyful benefits of the dam then look at actual dam below half missing.

[spnrx]

While it wasn’t a massive dam, the collapse of the Baldwin Hills dam in Los Angeles city was a result of saturated soil and building the dam near an oil field. This dam was in a highly populated area an was a miracle that the death toll was as low as it was.

[stischer]

Interestingly, growing up I was told that the Medina Dam holding back Medina Lake in Texas is used to show engineers how NOT to build a dam.

[karlmckinnell]

Love to see a comprehensive analysis of the upstream dams on the Yangtze. The cascading effects of an upstream failure would be as devastating as it would be unfathomable.

[RovingPunster]

IMO the main problem with major dams in China is NOT tofu dregs construction, but rather incompetent and/or corrupt mismanagement of their water resources.

The whole point of a dam is to mitigate both flooding and droughts by properly timing the release of water for both. You release during droughts, and (most importantly) BEFORE torrential rains and monsoon like weather patterns, so that there is enough spare storage capacity to absorb the huge inflows.

Instead, it seems like theyve been doing the exact opposite . . . hoarding water during droughts in order to sell it to farmers, keeping reservoirs at or near capacity all the time, and mostly just releasing during floods to prevent overtopping. Seems insane to me.

Compare and contrast that with the comparatively excellent practices on display in California. Night and day.

[hypsyzygy]

After the Italian dam disaster they assumed the dam had failed. When they went to check, the dam and its lake were intact and peaceful. That puzzled them.

[jonchowe]

I remember in the early days of the pandemic there were DAILY "rumors" and "reports" that 3 Gorges was buckling or breaking; so far, no sign those were true. It was some fascinating propaganda. Thanks for a level headed take! Praying this damn dam never breaks; the devastation would be like a world war, but over in hours.

[BA-gnqb]

A fish swam right into a cement wall and said "Damn!"

[ehsnils]

The aerial photos gives different deflection depending on the photo angle. The actual deflections aren't likely to be visual. If the deflections were as bad as the photos says then the dam would already have collapsed.
A landslide upstream of the dam is probably the most immediate risk. I'm not sure about how large a landslide can be upstream though. The largest landslide I know of was the Storegga slide (occurred somewhere around 6225–6170 BCE, so that's why you wouldn't hear of it in the news) outside Norway that caused a severe tsunami. But if there's a landslide with a tsunami that cracks the dam then it would be tough.
If the dam collapses then I suspect that it would have an effect all the way to the sea including Shanghai, but most of it would impact the basin in which Jingzhou and Wuhan are located.
I don't think that they have the tofu level construction on this dam since it's too important. There may still be construction flaws but those are harder to detect and likely to be rarer. If you live downstream of that dam you wouldn't want to cheat too much.

[allentisthammer]

Thank you, it is refreshing to listen to an articulate competent engineer sticking to what's known and what's not.

[oswynfaux]

The "inflection" is just the varying height of the structure showing in the skewed shadow because the satellite was not directly overhead

[audistik]

While some may not be satisfied with “I don’t know, ” I appreciate your honest and objective analysis of what can and can’t be known.

[BramBiesiekierski]

The water in the missiles story is not a literal happening. It is a metaphorical saying that has been lost in translation. Eg, there is not literally water in the missiles. But rather the missiles have been "watered down", meaning that along the way various individuals may have fraudulantly stolen, counterfeited or in other ways corrupted the missile program.

[barryminbiole]

As an engineer, I truly appreciate your balanced presentation of relevant facts and judgments.

[kvline]

One other commanding thing about rolled earthfill dams' reservoirs, such as Ft. Peck, Garrison Dam, Oahe, Ft. Randall, Big Bend Dam and Gavin's Point is that they not only fill up with water, but silt carried in the water. Several of these dams' reservoirs will be due for dredging soon. The U. S. Army Corps of Engineers was surprisingly informed that they should not commence dredging operations until major ceramic and porcelain manufacturers were consulted. They mentioned the high particulate material was justifiably worth "mining" for its concentration of high-quality silt for use in industrial ceramics. The Chinese face a similar threat with silting of the Three Gorges Dam. The Yangtze River is filled with particulate earth matter not to mention other debris, as the Missouri River carries, and eventually the reservoir will "silt up."

[PilgrimBangs]

I had seen one of those doctored pictures of the dam showing it was bowing. I was completely fooled, glad you cleared that up. I didn't know about any cracks though. Thanks for you doing this video.