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KingRBPII t1_iwizday wrote

Hoover dam could use it


admiralbundy t1_iwk7xpg wrote

Unfortunately it’s more extreme events and lesser annual rainfall. So bad news bears for humanity in general.


Numismatists t1_iwkqzcq wrote

Monsoons quickly fill dams with debris. We won't be able to keep up.


unswsydney OP t1_iwiyh4w wrote

Hi r/science, cheers for having us!

A joint study from UNSW and the University of Melbourne has found existing dams will be at greater risk under climate change than what is currently assumed.

Lead author on the research, Johan Visser, said, "some of the worst floods around the world were due to extreme storms overwhelming a dam, causing it to fail and release a wall of water downstream.”

The study was published in Water Resources Research today and is available to read:


Redvomit t1_iwjhtws wrote

Industry would sure appreciate a guidance note between now and development of any updated guidelines. Glad to see PMP getting a well deserved look through


LNMagic t1_iwk7qck wrote

It looks like this study focuses mostly on the likelihood of flooding or reservoir overfilling events. Does this take into account various dam construction methods? The reason I ask is that one of Texas' largest artificial lakes is dammed by an earthworks construction which has become increasingly leaky over several decades. If it were to fail, potentially half a million people could be downstream, and the dam is 20 years older than its designed lifespan.


admiralbundy t1_iwk848b wrote

How you mean construction methods? Dams generally are not supposed to overtop and the spillway prevents this. But if the rainfall is more intense the spillway may not be large enough, resulting in overtopping (which fails the dam).


LNMagic t1_iwm3x31 wrote

With earthen dams, sometimes you get water leaking under or through the dam. If a bulge isn't handled (usually by stacking sand bags on it to counter the pressure), you could end up with a runaway erosion with catastrophic results - especially with half a million people living downstream.


IdentityCrisisNeko t1_iwkwf1m wrote

I am a civil engineer and worked with dams for a bit (though I am by no means an expert). For what it’s worth, earthwork dams are always a bit leaky. You’ve got an enormous pressure difference on one side of the dam versus the other, and that pushes water through underneath the dam. That being said, that IS a design consideration. So I wouldn’t worry.

High profile dams like that usually have a lot of eyes on them, but if you’re worried I would find out which state department is responsible for handling dams (in Indiana, the department of natural resources handles dams for example) and shoot them a FOIA request! They should have some construction records and inspection records. In the past couple of years the dam community on the whole has opted to be more transparent about dams in general so I don’t expect the report to be useless.

There’s a chance that your dam is an army core one and then I wouldn’t worry about it. The army core does a pretty good job with their dam and levies.


boopmouse t1_iwkq2dw wrote

It's not about leakage, we're having regular floods here all over the East coast of Australia bc of dams overflowing.
The dams we have are in good condition so far, but catchment and holding areas aren't large enough to hold the amount of rainfall we're getting with the increasing intensity of La Niña weather pattern.


willowtr332020 t1_iwlbyg3 wrote

Just to clarify, we'd be getting floods with or without dams. Some (not many) of the dams are there to reduce (but not completely stop) flooding affects. Wivenhoe (QLD)is a flood protection dam. Warragamba (NSW) is not, it's a water storage dam (with a side benefit of some flood reduction).

The flooding is just happening because of the wet (LA Nina) period we are having as you've suggested.

We can't insulate ourselves from flooding due to the dangerous rainfall events in the report (like PMP events). In the PMP event you mainly want the dam to safely pass the water and stay structurally sound. Dan failure is worse than any natural flood event.


[deleted] t1_iwl6fs1 wrote



Dr_seven t1_iwogwar wrote

The real danger in the US is the ones FERC doesn't supervise. I'll actually politely contest your statement that most dams are federally regulated- most dams that are smaller are regulated at the state level (or at least, in my state they all are regulated that way) and those small ones are very common.

Of course, the small dams are in horrid shape and most haven't been adequately maintained in many years. They're not as catastrophic but we are still talking inundating thousands or tens of thousands of people sometimes depending on the location.

State agencies are much worse equipped to supervise such a vast field of infrastructure and so many don't, according to the correspondence and conversation I had with some engineers at my state's dam regulator. Those guys looked shell shocked and gave me like 12 hours of presentations and materials for free, saying I was the only owners representative in years to take any real interest in the dam on our property. Statewide. As in, they could not even reach live humans connected to any deeds or paperwork for most of their dams, and much of the rest was them getting stonewalled.

Silent and in the background, but terrifying.


DaveinOakland t1_iwj2yql wrote

Is this where I pull a boomer and just pretend it's not my problem since I'll be dead?


Tower21 t1_iwjh4el wrote

If you're old or just live downstream from a dam, yes.


clownslapnut t1_iwj7db9 wrote

Hopefully we will come to realize the importance of bringing back wetlands to dampen the effects of big rainfall events. The rate of trenching/breaking up wetlands in agriculture is compounding as equipment keeps getting larger and more advanced. There needs to be monetary incentives for landowners to keep wetlands, as controls to stop trenching are totally ineffective.


ian2121 t1_iwjd9st wrote

Wetlands are great for a host of reasons but have pretty minimal effect on flood storage. Most wetlands that have been destroyed haven’t been filed in they have been ditched and tiled which doesn’t affect flood storage volumes.


IdentityCrisisNeko t1_iwkwrhc wrote

I mean it’s less about storage and slowing the flow of water. Floods have gotten worse in our modern day in part due to climate change, but also the MASSIVE amount of impervious surfaces that move water far too quickly, backing up systems, and causing floods. Wetlands may not have great storage but they do a far better job at slowing water down than agricultural fields


willowtr332020 t1_iwlddfq wrote

The flooding referenced in the article (that of dams and their ability to pass flow) is not affected by wetlands.

Yes, impervious surfaces have increased but on a large scale, that's only really affecting cities with their storm water runoff. Flooding on the large scale we are seeing in Australia is not really exacerbated by the surface impermeability. River erosion and river roughness reduction due to vegetation clearing has had some impact, but the big change is the climate.


clownslapnut t1_iwjvf0j wrote

Trenching in our area is done for the reason of getting the water off the land as fast as possible. If water sits on our crop for any amount of time, it will perish. Not trenching means that we lose huge input expenses, so that is not economically feasible.


Redvomit t1_iwjl6bf wrote

Just wanted to elaborate on what a PMP is, and how it used.

PMP is probable maximum precipitation - which is an extreme rainfall intensity estimate. The probability of a PMP is often estimated as a 1 in 10 million year event or similar. However, many rainfall methods rely on using the PMP as an upper bound of rainfall intensity to estimate events rarer than the 1% annual exceedance event.

Therefore, this research may affect many structures, particularly those that are designed with extreme events in mind - which are typically larger dams and reservoirs.


elralpho t1_iwm64d7 wrote

This is a great example (one of many) of how it would have been cheaper to meet climate change mitigation goals. Think of the billions that will now need to be spent to update all of this infrastructure in coming years.


lucymx16 t1_iwjdv50 wrote

Plus most dams are damn old.


Tigen13 t1_iwk7h3i wrote

I am not sure age is much of a factor. All that concrete amounts to tons of dirt acting as a wall. I dont think time erodes them much.

These are just my thoughts. Buildings have beems that can weaken and then cause a collapse. All long as all the weight is there the dams should work. Water being too high and flowing over the dam obviously changes things.


2055265 t1_iwkxzoz wrote

Civil engineer here, age is definitely a factor. Time eats through concrete like any other material. Water will never flow “over” a dam, there are safeties in place, if it does you have much bigger problems.

Also “beems” in building are made of multiple materials, one being concrete. I appreciate the confidence, though.


Tigen13 t1_iwsmo1q wrote

What is the usual life of a dam?

For example the hoover dam is about 80 years old. How much longer will it last or what is done to extend the life?


2055265 t1_iwua3tb wrote

~100 years

The Hoover dam is a bit of an outlier because it is such a large project. The larger the dam the longer the lifespan usually. If cracks in concrete are found they will attempt to fix them by draining the water level for a time. The Hoover dam also contains no rebar which helps a lot for longevity.

Without human intervention the dam would collapse in 3-5 years. With regular service to the turbines but no structural work I’d guess ~50 more years.

But again, the Hoover dam is a huge outlier. We have over 80,000 dams in the US. Most of these dams will be brought to the edge of their lifespan, torn down, and rebuilt rather than repaired or retrofitted.


grrrrreat t1_iwj3ova wrote

I mean, isn't this more about the original designs not capable of handling new climate regime.

Headline is written in a very problematic way.

"Dams not designed for increased catastrophic flooding"


Redvomit t1_iwjk4w0 wrote

Note the journal article is titled "The impact of climate change on operational estimates of Probable Maximum Precipitation" which is similar to your wording


Difficult-Product223 t1_iwk6oj9 wrote

So put these guys in charge…since they are perfect modelers. Solutioned!!!


Distracted99 t1_iwkih9p wrote

Or, if you're a republican, "Will these damned hoaxes ever end!"


Top-Night t1_iwkkxqu wrote

The dam in that picture looks like an accident waiting to happen


patrickkannibale t1_iwkoye7 wrote

Can anyone tell where it is? The article doenst specificate, but I want to know cause the picture triggers my anxiety


annandin t1_iwkxkqw wrote

Gordon dam in Tasmania. A very impressive piece of engineering. The water level is quite low you can see from the vegetation where it used to be up to.


Top-Night t1_iwkpc9x wrote

According to Google lens it is the Gordon Dam, located in South West Tasmania, Australia.


willowtr332020 t1_iwlhn43 wrote

In what way?

You can abseil off it, if you want.


Top-Night t1_iwljg1b wrote

I’m sure it’s totally sound and safe, it just seems like an incredible amount of force behind it abd if it ever were to fail there would be catastrophic consequences. Not sure what’s below the dam.


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charmingpea t1_iwjk6p2 wrote

Do we have any assessment of the next likely confluence of the negative IOD, a positive ASM and La Nina all at once as we do now?


Hall_Michelle t1_iwotp2w wrote

Climate change is making extreme weather events more common, so it's not surprising that we're seeing more flooding at dams. What's worrying is that this trend is only going to continue in the future.


Coreadrin t1_iwk8ok4 wrote

I'm sure it will have nothing to do with the fact that governments meant to be maintaining these will be spending all of their money on servicing the loads of debt they've run up over the last 20 years, the demographic pyramid shifting, and will probably not be maintaining these as they should.


Numismatists t1_iwks046 wrote

Climate Forcing is at-play. Can't expect a stable climate when we keep randomly injecting aerosol pollution into the Ecosphere now can we?


Zomunieo t1_iwksadx wrote

Dam it. Dam it all to heck.


FriedFred t1_iwj7hxm wrote

This feels like something you could mitigate by changing the control regime of the dam - if you lower the “full” level, then be would be more spare capacity in the event of a big rainfall event, leading to the same risk of failure as before.


ian2121 t1_iwjdqfy wrote

That’s how flood control dams are already managed.


FriedFred t1_iwjeiaf wrote

Ah, thanks - these aren't reservoirs, they're smaller dams for flow management. Makes sense now.


Redvomit t1_iwjityt wrote

No, this affects all storages designed for extreme inflows. Arguably, smaller dams and reservoirs are less affected by this specific research (but are still affected by climate change impacts)


ian2121 t1_iwjiv56 wrote

Could be old hydro power dams or irrigation dams. Depends a bit on your climate and region. Speaking of flood control dams check out the Presa Rompepicos near Monterrey Mexico.


FriedFred t1_iwjn5wl wrote

Cor, that's a massive dam - I hadn't really appreciated that you might want to build something that big for the sake of flood management, rather than because you want to store the water for later (e.g drinking water reservoirs).

Does a structure like that aim to produce constant river flow, averaging out the wet and dry seasons? Is this sort of thing only common in places with variable climates?


ian2121 t1_iwjnwmw wrote

I’m in the PNW so l don’t know a ton about it but I believe the sole purpose of that dam is to minimize flash flood damage to the city


admiralbundy t1_iwk8e1g wrote

You can lower the full supply level to create airspace or a flood mitigation zone. This would trade off the available water supply in exchange for dam safety protection.

However, almost all dams in an extreme event are filled multiple times over by the inflow, thus making any lowering of the storage prior to the event futile.

But it is a valid point and in some dams can be useful.


Omiok t1_iwjengz wrote

Not only to change the operational levels by changing the dam crest elevation or the spillway intake level, there might be a need to adapt the spillway geometry overall or to add emergency spillways. There also may be solutions by changing the land use at the upstream catchmemt area, to increase the infiltration and reduce the direct flow. Anyway, sounds like ground for work to hydrological engineers worldwide.


Tigen13 t1_iwk7pik wrote

Insurance companies have a term "acts of god" for unusual weather events in which they don't have to pay out.

Climate change will likely bring more of these. Dams may not be able to relieve enough water in time. Or you can have a Pakistan event. 10x more rain than the historical average over an extended period of time.