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 Post subject: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 6:54 am 
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Climax
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Time to start a new topic pertaining to a rising and overflowing of a body of water especially onto normally dry land <The flood inundated the whole area.>; also : a condition of overflowing <rivers in flood>

http://www.kcra.com/article/water-stops ... ay/8736758
'While evacuation orders remain in place for many communities and cities around Lake Oroville and downstream along the Feather River, Lake Oroville has fallen below 100 percent capacity of 901 feet to 898.53 feet, as of 4 a.m., according to the California Department of Water Resources. At its peak, the lake was at 902.59 feet.

The flows into the lake are just under 45,000 cubic feet per second (cfs), while the outflows remain high at nearly 100,000 cfs by way of the damaged normal spillway, DWS officials said. However, officials are still looking to lower the lake another 50 feet, which could take a few days if the outflows don't increase."
Quick link to latest observations
http://www.cnrfc.noaa.gov/obsRiver.php?id=ORDC1

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 8:27 am 
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Rodger's Ridge
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If its taken 12 hours to fall 4 feet, wouldnt it take to Sat. to get to 50 ft down? 3 days after the rains start? And they'll be halting flow at times to see the damage. :?:

An OES spokesperson said Sunday that the potential failure of Lake Oroville's emergency spillway was "potentially catastrophic."

"But the dam itself is safe".

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 8:57 am 
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Climax
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Lots of factors to the equation, including rate of snow melt and freeze.
Notice the big ZERO on outflow at one point, inflow was fairly low at 14K input. Inspection time?
Whats with the missing inflow data?
http://cdec.water.ca.gov/cgi-progs/quer ... an=12hours

Date / Time RES ELE STORAGE OUTFLOW INFLOW RIV REL RAIN BAT VOL
(PST) FEET AF CFS CFS CFS INCHES VOLTS
02/12/2017 18:00 901.65 3563726 99969 42369 103022 34.76 13.5
02/12/2017 19:00 901.35 3558960 99758 40485 113169 34.76 13.5
02/12/2017 20:00 901.02 3553726 99658 37441 118405 34.76 13.5
02/12/2017 21:00 900.70 3548654 0 14784 118144 34.76 13.3
02/12/2017 22:00 900.34 3542956 99231 5237 118148 34.76 13.5
02/12/2017 23:00 900.11 3539318 99080 33762 115226 34.76 13.5
02/13/2017 00:00 899.77 3533936 98832 44890 114672 34.76 13.5
02/13/2017 01:00 899.44 3528727 98595 -- 114428 34.76 13.4
02/13/2017 02:00 899.13 3523839 99917 -- 114923 34.76 13.4
02/13/2017 03:00 898.82 3518956 99917 -- 115312 34.76 13.5
02/13/2017 04:00 898.53 3514392 99989 -- 115435 34.76 13.4
02/13/2017 05:00 898.19 3509047 99878 -- 115659 34.76 13.5

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Last edited by Spirit Tree on Mon Feb 13, 2017 9:37 am, edited 1 time in total.

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 9:12 am 
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Rodger's Ridge
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I cant read the light yellow!

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 9:39 am 
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Climax
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cheapski wrote:
I cant read the light yellow!
FIFY
Note to self - "Do not use light yellow"

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 9:55 am 
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Climax
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Latest observations for town of Gridley @ Feather River, Gridley is one of the towns under evacuation.
Already at one of the historical markers.
http://www.cnrfc.noaa.gov/graphicalRVF.php?id=GRIC1

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 10:15 am 
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Rodger's Ridge
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Torrent of water didn’t further degrade main Oroville Dam spillway

8:02 a.m. State officials said an early morning inspection of the battered main spillway revealed that ramping up the water releases did no additional damage to the main release point for the dam.

“There’s been no additional erosion on the main spillway,” said Chris Orrock, a state Department of Water Resources spokesman. “We will continue at 100,000 (cfs).”

Orrock added that while giant sandbags are being filled with crushed aggregate at a staging area overlooking the dam, it is still uncertain whether the aggregate will be helicoptered in to try to fix the erosion beneath the emergency spillway.

Read more here: http://www.sacbee.com/news/state/califo ... 79669.html

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 10:35 am 
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Rodger's Ridge
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This guy sounds more realistic.
http://www.sacbee.com/news/state/califo ... 56269.html

The Bee: If the top ​of the emergency spillway ​goes, is that basically dam failure?

Countryman: It’s not going to be the (main) embankment failure, but it’s a failure. If it does happen, there’s nothing saying that the ground is going to stay where it is. That force of water will start tearing that hill apart​,​ and it could eat back into the reservoir and drain the reservoir.

The Bee: If that happens​,​ is it a “who knows what will happen?” situation?

Countryman: Yeah, it’s speculation, but most of the speculation would be it’s not good. It will be a helluva mess downstream. I think they’re taking the right action. I think between now and Thursday​,​ when the next storm arrives, they need to get the reservoir down as low as they can. Tomorrow, they need to start grouting the hell out of that embankment to try to shut off where that leak is.


The magic number is 150k cfs because thats what the levees are built for.

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 11:49 am 
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Cornice Bowl
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Some things to keep in mind;
The levees he is talking about are the downstream levees that keep Oroville etc. from flooding. The "Failure" he is talking about is the top of the emergency spillway eroding away to a point where more than the 150k flow would be expected - NOT a full dam failure.

This is the 100 year flood scenario - the emergency spillway is not expected to come out of this unscathed. That would be like So Cal getting hit with an 8.0 earthquake. You will see damage. Structures are designed to protect life at that point. Yes it's inconvenient, but nobody has died, the emergency spillway has done its job.

I think the evacuations were prompted more because the emergency spillway is the final fail-safe.

Also worth noting; without the dam, Marysville and Yuba City would already be flooded. It happened in the 50's before the dam was built. My Mom lived in Marysville during those floods - I think she was about 12 at the time. It was HUGELY traumatic to all involved! She still remembers it and can relate it in great detail to this day.

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 12:18 pm 
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Rodger's Ridge
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Well, when they start rebranding the emergency spillway as the "auxiliary" spillway they downplay it to the public. I noticed them starting that over the weekend. Its the last protection. Thats why if you read the rest of the interview he says,

The Bee: What happens tomorrow?

Countryman: ​You’ve got this dilemma: You’ve got a broken spillway that you don’t really want to be putting large flows down. But you don’t have any alternatives now. Now, you’ve got to put more water through it​, and you’re endangering (that structure). Tomorrow, when you wake up and we can get a good view of it​, you may see that those gates are in trouble. If they’re not – if they’re making this 100,000 cfs release (and) the gates are in a safe condition – then we’re in a pretty good position to ride it out.

The Bee: That means you can lean on the spillway full throttle?

Countryman: Exactly. And the channels can handle it. They were afraid to open it up because they didn’t know the broken spillway could handle it. Now they’ve been forced to open it up, and tomorrow we’l​l​ find out
if it worked.


Apparently its holding for now.

No he wasnt talking about a total dam failure, but he said if that emergency spillway failed while the water level was really high it would still send water crashing down the channel. I'm not sure why the reporter was talking about the top of the spillway when it seems to me if there was serious erosion at the base of the structure it would topple over from being undermined (Edit: I realize now he was talking about the cement portion). Or a big crack would form and the water would force its way out from that.

IMO the emergency spillway didnt do its job since they had to go back to the 100k cfs release on the main damaged spillway. Pic of the erosion here: http://fox40.com/2017/02/12/water-no-lo ... -spillway/

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 1:07 pm 
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Center Bowl
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"I think the evacuations were prompted more because the emergency spillway is the final fail-safe"

The evacuation were prompted because the emergency spillway outflow was creating rapid uncontrolled erosion that was retreating upwards toward the concrete brim at an alarming rate, they were convinced that it would reach the rim within the hour and at that point would have a major uncontrolled release of water from the reservoir. I believe they said there would be a 30 foot wall of water racing down river. They were forced to release as much as the could down the damaged spillway to try to slow the overflow and fortunately it worked, that or the erosion hit bedrock or a more resistant layer. Another problem was that the water was starting to overflow the parking area which was not designed to handle an overflow of water from the reservoir. They will not admit to it but they got lucky. They were forced to take actions that they were not sure of the outcome of and fortunately it worked. It's funny because just a few days ago they were saying there was absolutely nothing to worry about. It reminds me of the St Francis / Mulholland Dam disaster, people down stream were guaranteed that the Dam was sound and there was no risk of collapse only to have it fail later that night and drown 450 people.


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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 1:25 pm 
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Dave's Run
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There is so much downstream protected by the levee system, failure could occur at any point.

1997 - http://articles.latimes.com/1997-01-03/ ... ther-river

And of course, it feeds into the Sacramento River, which also protects Sacramento from floods. Only the eastern parts of the city would be safe from levee failures.

PS - Carson Valley looked under water last week


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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 1:29 pm 
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There's already an unrelated levee failure.

Sacramento County are advising residents in the Tyler Island area south of Walnut Grove to evacuate due to a compromised levee, officials said Monday.

There are about 20 homes in the area, said Sacramento County Water Resources spokesman Matt Robinson. Tyler Island is protected by a ring levee.

The county expects imminent failure of the North Fork Mokelumne River levee, according to the National Weather Service.

The evacuation is unrelated to concerns about the Oroville Dam emergency spillway that has forced evacuations in cities along the Feather River.

http://www.sacbee.com/news/state/califo ... 35374.html

If you think about the huge length of the Sierra snowpack and all that water drains down to the Central Valley at some point, wow.

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 1:54 pm 
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Rodger's Ridge
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Satellite photo of Sac valley from yesterday

Image

Hi res here: http://imgur.com/a/acvW0

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 Post subject: Re: 2017 Flooding...
PostPosted: Mon Feb 13, 2017 2:01 pm 
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Waiting for comparison pic...


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