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[Oroville Dam] Please Stop Raining
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E:
http://www.latimes.com/local/lanow/la-me-ln-oroville-weather-forecast-20170216-story.html
@Pellaeon
Source?
Edit: ah I see, wasn't getting those numbers here but downstream so I don't get the same level of accuracy for that area. Also sounds like they revised it recently. Fun times...
In short, this damage is caused by cavitation, which is also how pistol and mantis shrimp hunt their prey. Basically, as millions of gallons of water rush over the concrete spillway, tiny cavitation bubbles are formed on the surface of the concrete due to the rapid changes in pressure cause by such amounts of water moving at such speed. As the bubbles collapse, they release energy that over time damages the structure, eventually resulting in the collapse seen above.
Interestingly, arreration gates can be installed to avoid this exact scenario, as was done in the 80s following similar problems at the Glen Canyon Dam in Arizona and subsequently Hoover and Blue Mesa dams, however this particular dam in Oroville never received the upgrades. They're now looking at repair costs in the billions while the preemptive fix of installing arreration gates would have cost only a few million.
Rain's started, here's the current state.
I know the practical effects of it are shitty and dangerous, but the mechanic of it is actually really neat and something I would have in no way thought of.
Monday in particular is going to be crazy
Incoming!
So Monday evening will definitely be the time to keep an eye out on the dam - if we can make it through Tuesday, I think we should be out of the woods.
https://m.facebook.com/story.php?story_fbid=1683579861668957&id=100000508772678
Per county supervisor:
Peak inflows over 100,000 cfs, but average under 70,000.
Minimal additional damage to spillway (major concern was upwards creep of the collapse)
"Nothing even resembling a problem."
Per me, they've cleared a lot of room over the last week or so to deal with storms.
Spring, with sustained runoff from the melting heavy snow over this year is more worrying.
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I was concerned your drought was gonna break in this fashion. I really was hoping for a nice extended minor deluge that the ground could've kept up with.
Glad to see things are looking a bit more under control.
and in 1000 foot tall letter above that it should read "HEY MAYBE WE SHOULD ACTUALLY FUCKING SPEND MONEY ON INFRASTRUCTURE"
-Indiana Solo, runner of blades
Good news! Hippies have volunteered to write the image in moss!
Mosses are pretty slow growing. There are two classes of moss, and the faster one can approximately double in size in ideal conditions in 6 months.
I mean, yes, but that's not really what happened here. They could have put in the aeration gates, but I don't know that California has done many of those. The federal dams have, but it seems to be mostly for the flood control dams that use the spillway much more often.
Even when that happens, I imagine the process would make for a pretty neat timelapse.
It's just how we roll. Last year we were having floods and wildfires at the same time. Nbd.
Somewhere in my possessions I have a picture from my youth growing up in West Palm, which is of a "Danger: Extreme Drought. Do not dispose of cigarette butts" sign that was posted in the drainage ditch along the highway. Everything but "Danger: Extreme Drought" was under about 3 and a half feet of water from a week of insane thunderstorms.
They dropped it 50 feet since the crisis, so they have a decent amount of a storage. They've dropped the outflow from 100k cfs to 60k since then, looks like it's only recently exceeding that in inflow (90k cfs or so)
And just think, events like this will only become more common due to global climate change increasing the intensity of weather around the world. Yay!
Yeah but once those snow caps stop forming you'll have nothing to worry about.
http://sanfrancisco.cbslocal.com/2017/02/21/rescue-crews-pull-residents-from-flooded-homes-in-south-san-jose/
It's easy to figure out. 810,714 acre-feet to 1 cubic kilometer.
Basically the same as my odds of piloting through an asteroid field while being shot at by the Empire.
Dam well.
Dunno. Storm that hasn't hit yet was expected to fuck the Bay Area and the Central Coast pretty bad but it looks like it's calmed down. Looking at the storm system it didn't look like it was really hitting further North.
I guess wait until the dry season, drain as much as they can and then bust ass to get the spillway fixed?
I wonder if they'll shore up the emergency spillway first
Vis a vis repairs: there isn't going to be much of a dry season. Runoff will continue through probably July this year, then a break until maybe oct/nov when storms usually start up.
The other thing that hasn't been mentioned here, iirc, is that there is a power plant at the base of the dam. It has been damaged during this incident, but when it's repaired and running it can pass up to 13000 or so cfs by itself, and draw much lower than the spillway.
So first order of business is fix the power plant, switch to using that instead of the spillway, then evaluate the main spillway.
To buy time for repairs to the main spillway theyll have to draw down and hope there's no major inflows during construction.
Repairs to the auxiliary spillway are ongoing and will continue.
Yeah... Snowpack is at 150% of average right now. Once that starts to melt they can't really stop operating the dam, and assuming we don't immediately return to drought conditions, it used to be normal for that area to have very wet Falls.
Yes, but it's enough to keep up with inflow outside of major storms coming through.