Do dams pregame?

Submitted ⁨⁨3⁩ ⁨days⁩ ago⁩ by ⁨AA5B@lemmy.world⁩ to ⁨[deleted]⁩

This is a stupid question mostly because I don’t know where to ask it. Also it seems like an obvious thing but I’ve never read any news mentioning ……

I was just reading an article going over recent flooding catastrophes and one thing that stood out was a dam adding to the high water by having to release water while the flooding was still happening.

But can’t dam operators see a storm forecast and start drinking, er draining, ahead of time? It’s seems like you could make a big difference in controlling flooding with just a day or two pregaming. That can’t be profound, so why does it never seem to be mentioned? It could be a significant factor on many floods, a critical use for NWS data, forecasts, warnings, so where are the news mentions?

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FuglyDuck@lemmy.world ⁨3⁩ ⁨days⁩ ago
short answer is yes, they do.

But like in texas, they didn’t have enough warning and accurate enough information on how much to let out. you can blame that on trump’s NWS/NOAA/Airforce. (the AF provides access to satellites operated by the military, and that’s stopped for whatever reason.)

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- AA5B@lemmy.world ⁨3⁩ ⁨days⁩ ago
  This needs to be more public
  
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fuckwit_mcbumcrumble@lemmy.dbzer0.com ⁨3⁩ ⁨days⁩ ago

But can’t dam operators see a storm forecast and start drinking, er draining, ahead of time?

Yes, they already do this. When rain is expected they lower the levels of the dam. Even just smaller rainfalls not quite flooding territory. But there’s only so much water you can drain before it starts causing problems for the dam.

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thevoidzero@lemmy.world ⁨2⁩ ⁨days⁩ ago
As others have mentioned they already do that to a degree they can with the uncertainty of forcast. It’s called Forcast Informed Reservoir Operation (FIRO).

Important thing is that the forecast is uncertain farther you go in future, and smaller the area you’re looking at. So the policies will have to take that into account, you can’t simply empty your reservoir because if your forcast is wrong and you don’t get enough rain, then you don’t have the precious water anymore for dry season. But if you’re wrong on the other side you get flood issue.

Satellite data and a lot of ground sensors are in place that help us better forcast the future storms along with improved computation and technology, but nothing is sure, and it might get worse with current situation. We already have problems because of previous funding cuts causing us to lose so many sensors.

Also a fun fact, we’ve had dams for so long that we don’t know the natural flows for so many rivers so we can’t calibrate our models well. Basically we built dams long before we started measuring the rivers. I’ve been meaning to publish this, but it’s just stuck in a draft for almost a year now :(

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- AA5B@lemmy.world ⁨2⁩ ⁨days⁩ ago
  Thanks for lots of good detail I’ve never seen befire
  
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  - thevoidzero@lemmy.world ⁨2⁩ ⁨days⁩ ago
    Flood control is very close to my area of research. My research involves effect of dams on river water and I don’t get to talk about it often, so it was fun. But I haven’t actually worked on a dam control or made policies, so my work is more theoretical what ifs.
    
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litchralee@sh.itjust.works ⁨2⁩ ⁨days⁩ ago
For an example of when a dam is teetering upon catastrophic failure, with operators stuck between a rock and a hard place, see the 2017 Oroville Dam crisis: en.wikipedia.org/wiki/Oroville_Dam_crisis

This was covered in a Plainly Difficult video on YouTube, as well as other channels like Practical Engineering (also on YT).

Essentially, in that situation, the operators were discharging water until they found the main spillway was becoming damaged (uncovering shoddy work from decades ago). But the amount of rain meant that using the never-tested emergency spillway might actually damage the dam foundations. So in the end, they had no choice but to use the main spillway, as the less worse of two awful choices.

Known only after the fact, 2017 was a particularly wet year in California, coming after years of drought conditions. So holding onto water within the reservoir wasn’t imprudent. But a flaw in the main spillway, and lack of testing of the backup, made a bad situation worse.

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- AA5B@lemmy.world ⁨2⁩ ⁨days⁩ ago
  So they were relying on 47 year old charts, not updated for climate change, to guide their operations. That seems mighty suspicious
  
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givesomefucks@lemmy.world ⁨3⁩ ⁨days⁩ ago
Dams are set up in an area that a large amount of surrounding area naturally flows water into.

That’s why dams are constantly letting water out, even when it hasn’t rained.

So like, so X is the total amount of water before the dam overflows. You’d want to keep normal level at X - 25%. But if a storm is coming in they do pre-emptively open the floodgates and go down to X - 50% or whatever.

One of the big problems is these large storms last so long, days rather than hours. And even if they open the floodgates at the dam to help the lake, it makes it worse for people along the river it feeds into.

There’s no simple solution, we already started doing all that decades ago. It’s what was hiding the problem and why so many ignored it and it got so bad.

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Proprietary_Blend@lemmy.world ⁨2⁩ ⁨days⁩ ago
open.spotify.com/episode/05YjJrYAzD6u2wDOLaYLLM

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- AA5B@lemmy.world ⁨2⁩ ⁨days⁩ ago
  Cool, it’s on my queue. I don’t generally listen to podcasts but a bunch of their titles look interesting . Thanks
  
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