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What's going on in Oroville?


dgul

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Well, it is only mini-doom for a Sunday night, but it looks like the Oroville dam in northern California is close to breaching.  They're evacuating the town, etc.  It seems pretty chaotic.  They're expecting something doomy to happen in the next few hours*...

Live news reports here:

http://www.kcra.com/nowcast

For those catching up, the main spillway is broken, and they're using the emergency spillway, which all of a sudden seems to be structurally unsound.

[*or maybe no doom will happen.  You just can't tell.]

 

 

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What they seem to be saying is that the main spillway is being heavily damaged and this is being worsened by the volume of water being allowed trhough it, so will cost a lot to repair, and the emergency spillway, a wide area where the lake is reservoir is allowed to overtop, may begin to be damaged so the flow here will be much higher, and if a section falls away from this area then there could be a 30ft wall of water powering down into the valley.

So the main dam isn't at risk but the sidewall is and this is 30ft high.  I don't blame them for evacuating even if the rain has stopped.  

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15 minutes ago, Frank Hovis said:

What they seem to be saying is that the main spillway is being heavily damaged and this is being worsened by the volume of water being allowed trhough it, so will cost a lot to repair, and the emergency spillway, a wide area where the lake is reservoir is allowed to overtop, may begin to be damaged so the flow here will be much higher, and if a section falls away from this area then there could be a 30ft wall of water powering down into the valley.

So the main dam isn't at risk but the sidewall is and this is 30ft high.  I don't blame them for evacuating even if the rain has stopped.  

I've seen Evan Almighty. They need an arc.

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Trump will get the blame.

California is a bizarre state. Companies and people are fleeing it due to its high taxes but those taxes rarely seem to be spent on any infrastructure. There has been no longterm plan for anything it seems such as water provision, roads, rail. Crazy. But most of its population feel the need to lecture everyone else in the US on how to do things.

They are desperate for water but when it rains they don't have enough dams to hold the water.

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3 minutes ago, The Masked Tulip said:

Trump will get the blame.

California is a bizarre state. Companies and people are fleeing it due to its high taxes but those taxes rarely seem to be spent on any infrastructure. There has been no longterm plan for anything it seems such as water provision, roads, rail. Crazy. But most of its population feel the need to lecture everyone else in the US on how to do things.

They are desperate for water but when it rains they don't have enough dams to hold the water.

Have you read The Grapes of Wrath.
 

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26 minutes ago, rollover said:

That's what they think:

Image result for oroville overflow

 

Now:

Image result for oroville overflow evacuation

 

Your second picture is the emergency spill way; it's there for the water to pour over like that.  The problem would be if that eroded and fell away and then you have that level of water (which I presume to be the 30 ft quoted) pouring down that, eroding further and getting faster.  Even then you're only top-slicing the water level, you're not emptying the reservoir from the bottom as would happen if the dam failed.

It's not the main dam that's at risk as that is 20ft higher than the spillway, so not over-topping and eroding its base, and there is a big ridge between it and the two spillways.

It's dramatic and evacuating the populace is wise.

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That's a serious amount of water erosion from just a few days worth. The damaged spillway has cut into that ridge base a lot which will serve to weaken the dam. .

They've then used the auxiliary/emergency spillway but again they've got a lot of erosion damage there and a new storm front is hitting on Wednesday with the lake now at full capacity. 

The question is will it hold up until summer. How much more rain and corrosion can the surrounding hillside take.  If that ridge starts giving way there goes the dam. 

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That ridge looks nice and soild in the photo but plenty of times in California large amounts of soil have just rapidly eroded. The stuff, when baked hard, is like cement but it can quickly crumble and fall away when saturated.

Any moment now an earthquake will be along just to complicate things a bit further.

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13 minutes ago, Frank Hovis said:

Your second picture is the emergency spill way; it's there for the water to pour over like that.  The problem would be if that eroded and fell away and then you have that level of water (which I presume to be the 30 ft quoted) pouring down that, eroding further and getting faster.  Even then you're only top-slicing the water level, you're not emptying the reservoir from the bottom as would happen if the dam failed.

It's not the main dam that's at risk as that is 20ft higher than the spillway, so not over-topping and eroding its base, and there is a big ridge between it and the two spillways.

It's dramatic and evacuating the populace is wise.

You are correct.

There is damage to the auxiliary spillway dam weakened by rain.

The Oroville weather forecast doesn't look good, more rain on the way. google

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14 minutes ago, workingpoor said:

From what i have heard about traffic levels in California it is gridlock city on a good day, those sitting in queues of cars would do better taking off for high ground on foot no? 

Was it Malibu that got fined a few years back because it had signs directing people to escape a tsunami on foot but the signs pointed to dead ends or the local Hollywood celebs had allegedly blocked the escape routes. I recall reading something along those lines. But the advice ws to escape on foot upwards as opposed trying to do it in a car.

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