Aging dams threaten millions of people
February 7, 2021 10:25 AM   Subscribe

"About 130 people are feared dead in northern India after a Himalayan glacier broke off and caused a high velocity surge of water down a river, sweeping away one dam in its path and damaging another," according to a report from The Guardian and many other outlets. Nobody knows yet why a chunk of the glacier broke off, but a recently published study estimates that "5 billion tons of desert dust disperses into Earth’s atmosphere every year. Some of it makes its way to the roof of the world — the Himalayas — where it warms glaciers and accelerates snowmelt." But this FPP is not about glaciers; it is about dams.

Do not misunderstand; the avalanche of water, mud, and rocks that swept down a narrow gorge in the Himalayan state of Uttarakhand today is a horrific tragedy that appears to have been prompted by environmental factors. "Hridayesh Joshi, author of Rage of the River, about a similar flooding incident in Kedarnath, Uttarakhand in 2013 which took almost 6,000 lives, said that experts and activists had already been raising questions over the dam and road projects. 'In this Himalayan area, there are 10,000 big and small glaciers so we should be very careful about building any development projects in this ecologically fragile region, especially as climate change makes it even more fragile,' said Joshi."

That is surely true. Another truth, covered in Yale Environment 360 in an article by Fred Pearce, is the looming threat to life as tens of thousands of large dams across the globe reach the end of their expected lifespans.

The World Bank estimates that there are some 19,000 large dams more than 50 years old, which suggests there will be future tragedies, according to a new report from the UN. Consider the Kariba Dam, built by the British on the Zambezi River in Southern Africa 62 years ago. "Back then, it was seen as Africa’s equivalent of the Hoover Dam. But in 2015, engineers found that water released through its floodgates had gouged a hole more than 260 feet deep in the river bed, causing cracks and threatening to topple the concrete dam, which is 420 feet high and holds back the world’s largest artificial lake.

"Downstream are some 3.5 million people, as well as another giant dam, the Cahora Bassa in Mozambique, that engineers fear would probably break if hit by floodwater from a Kariba failure. Despite the urgency, the $300-million repair work won’t be finished until 2023 at the earliest.

"Both dams exemplify the potentially dangerous mix of structural decay, escalating risk, and bureaucratic inertia highlighted in a pioneering new study into the growing risks from the world’s aging dams, published in January by the United Nations University, the academic and research arm of the UN. It warns that a growing legacy of crumbling dams past their design lives is causing a dramatic increase in dam failures, leaks, and emergency water releases that threaten hundreds of millions of people living downstream. Meanwhile, safety inspectors cannot keep up with the workload."

The UN report, Ageing Water Storage Infrastructure: An Emerging Global Risk, was linked to on the front page and can also be found here.
posted by Bella Donna (22 comments total) 30 users marked this as a favorite
 
I believe the Banqiao dam disaster alone makes hydropower among the most dangerous energy sources in the world by fatality rate.

I can’t find my original source, but there’s a striking graph in this medium article, showing Banqiao versus Chernobyl.
posted by chappell, ambrose at 11:19 AM on February 7, 2021 [6 favorites]


Wow, that Kariba Dam is scary. Learning from the Kariba Dam (NYT piece).
I poked around and the latest news is marginally optimistic but who knows. First they started remediation in 2018 and is supposedly 60% complete currently. Second the water levels hit record lows, and is barely at the minimum for power generation. Talk about a mixed blessing.
posted by storybored at 11:24 AM on February 7, 2021 [1 favorite]


In 2014 a dam in Washington State had a crack discovered which had to be repaired. This infrastructure problem is world-wide.
posted by hippybear at 11:28 AM on February 7, 2021 [2 favorites]


Once again, I wish that Marc Reisner were alive to witness and comment on this. Reisner was the author of Cadillac Desert, a book mostly on water and the American West but one that also addressed water management in America generally. The book came out in 1986 (updated in 1993) and thus is out of date, but its prophetic nature leads me to think of it whenever I contemplate, say, the growing population of the Sun Belt, and particularly the Southwest, where there really wasn't enough water to begin with. It's relevant here because of the continued reliance on dams and America's generally decaying infrastructure.
posted by Halloween Jack at 11:29 AM on February 7, 2021 [7 favorites]


It's not just the big dams you have to worry about. In the US alone there are tens of thousands of unmaintained or poorly maintained privately owned (mostly earthen) dams holding back everything from small farm ponds that might cause some property damage in the worst case to lakes large enough to inundate cities of several thousand people. Most of them aren't even regulated by the state in which they are located in any meaningful way. Only fairly recently have we even had an inventory of such structures.

Even where the lack of maintenance hasn't actually compromised the structure, they are in most cases ill equipped to deal with the increase in stormwater flows brought about by climate change. It's a damn miracle there aren't hundreds of dam breaks every year. Turns out that most of them are overbuilt enough that they don't fall catastrophically even when pretty severely compromised, but that's really just down to luck and them not yet being all that old.
posted by wierdo at 11:59 AM on February 7, 2021 [8 favorites]


Not to make this too US-centric, but we're less than a year removed from successive dam failures in Michigan, displacing thousands and flooding a city of 40,000.
posted by miguelcervantes at 12:06 PM on February 7, 2021 [5 favorites]


Not just dams for water storage purposes but tailings dams as well whose collapse often has an even greater impact. (previously).
posted by adamvasco at 12:07 PM on February 7, 2021 [4 favorites]


There's a story I heard which I would love to find more about: a sociotechincal dam safety system, I think it was in Japan. It was to protect widespread small un-staffed (hydroelectric?) dams out in the country, which under rare heavy rain weather systems, could be at risk of overflowing unless bypass valves were opened. But how to have enough trained staff on hand for the very rare occasions when they might need to open all the spillways across the land on short notice?

The solution apparently was to design a clever user-friendly dam control system so that any local farmer could reliably know when they needed to drive over, could access the facility, check what they should do, and carry out the manual spillway-opening operation themselves. Ergonomics, security, signage, and control coordination were all apparently considered. After all, who is more motivated to be sure the dam is safe than the people living downriver?

Not a solution for the capital investment and risk acclimatization problems of maintenance, but something.
posted by anthill at 12:59 PM on February 7, 2021 [18 favorites]


That’s great, anthill, because we need examples of other ways things could work.
posted by clew at 1:37 PM on February 7, 2021 [1 favorite]


It's not just the big dams you have to worry about. In the US alone there are tens of thousands of unmaintained or poorly maintained privately owned (mostly earthen) dams holding back everything from small farm ponds that might cause some property damage in the worst case to lakes large enough to inundate cities of several thousand people.

It's not just that there are countless legacy low-head dams almost everywhere in the world, but they are prohibitively expensive to either upgrade or remove. They don't offer the safety concerns that high-head dams or tailings dams do, but their collective ecological impact is huge.

In the US, if you are in a river system with ESA-listed species, there is at least a chance of being able to get the funds to design and implement fixes and removals. Outside of that, options are limited, and even within rivers with ESA species there is only funding to deal with a fraction of the legacy dams. Because removal is so expensive, they are almost invariably just left in place until or unless something happens to force dealing with it.

The videos of the water coming down the river after the glacier break are scary to watch. Such a huge volume of water and debris, traveling fast.
posted by Dip Flash at 1:45 PM on February 7, 2021 [1 favorite]


The future is a negative externality.
posted by villard at 3:31 PM on February 7, 2021


.
posted by ChuraChura at 5:02 PM on February 7, 2021 [1 favorite]


makes hydropower among the most dangerous energy sources in the world by fatality rate.

It's not as direct as pointing to a person drowned by a failed dam, but the smog emitted by coal and gas plants can be attributed to tens of thousands of early deaths in the US each year. It's not even close.
posted by Popular Ethics at 5:41 PM on February 7, 2021 [9 favorites]


The thing about deliberately constructing geology is that the design considerations really need to blow out to geological time scales. This is hard for us to do, because even as a species we're complete n00bs compared to most of the processes that operate at those scales.

To my way of thinking, the failure of imagination responsible for dam disasters is the same one responsible for global warming and the same one that will ultimately be responsible for the failure of anything a human being could possibly design for the retention and isolation of radioactive waste. We're just not very good at dealing with processes that we think of as slow.
posted by flabdablet at 11:07 PM on February 7, 2021 [4 favorites]


countless legacy low-head dams almost everywhere in the world, but they are prohibitively expensive to either upgrade or remove

Why to remove? I’m thinking of farmer-made push-up dams, but I thought the removal method was to go out in the dry season and shovel the top of the dam into the reservoir, as many seasons as it took. Annoying, but cheap.
posted by clew at 12:12 AM on February 8, 2021 [1 favorite]


Dams is it? The Mosul Dam in Iraq was built on gypsum and holds back 10 cu.km of water. What's there is the result of surveys and reports from dozens of consultant engineers from half a dozen different countries. Despite slapping in a bed of grouting 25m thick before construction and 100,000 tons more grouting since. There are still untreated voids under and around the structure and 10 cu.km of water is heavy. 2 min exec summary.
posted by BobTheScientist at 2:22 AM on February 8, 2021 [3 favorites]


Looks like I had overly high expectations of ages for dams. Fifty and sixty-two years seem downright youthful for (CE) structures.

" ... the failure of imagination responsible for dam disasters is the same one responsible for global warming and the same one that will ultimately be responsible for the failure of anything a human being could possibly design ... "

That offers a lens to focus my future expectations better.
posted by filtergik at 4:53 AM on February 8, 2021


Why to remove? I’m thinking of farmer-made push-up dams, but I thought the removal method was to go out in the dry season and shovel the top of the dam into the reservoir, as many seasons as it took. Annoying, but cheap.

So, obviously this covers a wide gamut of situations from cheap to expensive. A small earthen impoundment at the top of a dry wash is different from a concrete legacy low-head dam on a perennial stream, for example. And, it is going to vary significantly by where you are (ie, what the environmental and engineering regulations are), not just in terms of what country you are in but also whether or not the dam removal has the potential to impact endangered or other species of importance, whether there is risk to human life or infrastructure, etc. If there was upstream mining or industrial activities, then you likely have a situation of contaminated sediments behind the dam, which raises costs and complications hugely. Are there important cultural resources to consider? (The same places that make sense to build a dam were often used for thousands of years by past inhabitants; moreover, many of these dams are themselves old enough to be require cultural resource consideration and documentation.)

So at one extreme, a farmer deciding to remove a small earthen impoundment is going to be a simple DIY job, yes. But a typical low head structure removal or fix on a flowing stream is almost always a multiple year endeavor. First there is the assessment, identification, and prioritization process to determine removing that structure vs any of the other structures in the system. Let's say that is done and you are ready to apply for funding from public or private sources. You would typically apply this year for funding starting next year. Then, once funding is secured, you then hire an engineering firm to survey and design the removal. The engineering process is probably going to take between 3 and 12 months, sometimes longer; the environmental permitting can take 6 to 18 months (and much longer if there is critical infrastructure, public controversy, or other complications).

So if you were applying for funding this year, you would be designing in 2022 and hopefully doing the removal in 2023 if all goes well.

Why all that cost? Because a structure that has been in place for decades has caused changes to the stream, and you need to design the removal to not cause more problems than you solve. Fish passage, vertical and lateral stability, sediment transport, and recreational users (like boaters or swimmers) are all things that need to be considered and included in the design process. The actual removal itself is also a complicated and expensive endeavor, with a specialized construction company performing work area isolation and sediment and turbidity control as required by the permits. Usually there is a narrow window of time (defined by lowest expected impact to aquatic species) when in-water work is allowed, so all the instream work in an area occurs in the same compressed period.

The frustrating part is that most of these dams were built with zero consideration of long term effects and usually without much actual engineering involved. They were cheap to build but they are expensive to remove -- it is a classic case of pushing costs onto future generations.
posted by Dip Flash at 6:07 AM on February 8, 2021 [5 favorites]


The above isn't meant to distract from the point of the FPP, which is more about the safety issues of large dams. Those are many orders of magnitude more expensive and technically difficult to remove or upgrade than the low-head dams. And climate change is making past dam safety analyses irrelevant -- not many dams were designed to accommodate flood and debris flows from melting glaciers, for example.
posted by Dip Flash at 6:17 AM on February 8, 2021 [1 favorite]


is there...is there anywhere you can look up whether you live in the path of dam failure-related catastrophe?
posted by schadenfrau at 9:31 AM on February 8, 2021


If you're in the US, the national dam inventory is online somewhere. I've used it in the past, but don't currently have a link, sorry.
posted by wierdo at 11:28 AM on February 8, 2021 [1 favorite]


If you are in California, turns out you can check out Inundation Maps that show "flooding that could result from a hypothetical failure of a dam or its critical appurtenant structure. In 2017, the California Legislature passed a law requiring all state jurisdictional dams, except low hazard dams, to develop inundation maps and emergency action plans. DSOD approves inundation maps, and Cal OES approves emergency action plans."
posted by Bella Donna at 11:38 AM on February 8, 2021 [1 favorite]


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