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labrat
Trad climber
Erik O. Auburn, CA
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Feb 16, 2017 - 04:37pm PT
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^^It's a great video of how things go right when correctly engineered. It did exactly what it was supposed to do.^^
Look up the Teton Dam video if you want to see one that went bad.
Added the video
https://www.youtube.com/watch?v=cdOGPBnfoKE
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Mule Skinner
Social climber
Bishop
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Feb 16, 2017 - 04:50pm PT
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Maybe this will wash all the crank out.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 16, 2017 - 05:21pm PT
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Awesome Cali dam history .ppt labrat ^^^ thanks for posting
Over on the Metabunk thread, they still seem confident that the folks down stream of the Oroville dam are safe...
The concern would be with the "cliffs" in the waterfall region, the lower down ones are not too important. The most important one would be by the transmission towers (although they are going to move them anyway).
Given the pounding and spray already, I suspect that some rain isn't going to do much damage. The hillside is relatively stable and has been there for decades (if not thousands of years). Maybe a bit more surface erosion.
Looks like the latest weather forecast just got worse...pineapple express on its way
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aspendougy
Trad climber
Los Angeles, CA
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Feb 16, 2017 - 08:48pm PT
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With that much water already there, and more on the way, there is a chaotic element which makes it difficult to predict the final outcome. It is very interesting to read about 1861, what happened back then. The dams make for much better overall control now versus back then, but on the other hand, there are many more people now living downstream in vulnerable places.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 16, 2017 - 09:13pm PT
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Read more here: http://www.sacbee.com/news/state/california/water-and-drought/article133030359.html#storylink=cpy
I think this is exactly what you were getting at when you talked about the flood procedures of the Oroville Dam earlier in this thread. Frankly I was surprised to read that the operating procedures were not updated after the '97 flood, and it turns out, the '86 flood as well.
I posted a link to one of Willis' papers up thread.
The comment that DWR should speculate about the future, and so ignore what we know about climate change, is sort of beside the point.
The fact is that the dam flood diagrams were constructed with the weather records from 1910 to about 1960.
We could certainly update these to incorporate the weather history since 1960, and even have a periodic review (every 5 years? every 10 years?) and update with the additional information.
Further, studying climate change has brought a large body of history of California weather through paleoclimatology, I think there are annual reconstructions of rain patterns going back 1000 years, and perhaps 10000 years. It is hard to understand how that information wouldn't firm up our knowledge of flooding, and provide important information for flood control.
Finally, everyone may have missed the fact that the flood control diagrams do not use any forecast information.
The flood control considers the average daily precipitation of the past 6 weeks. Certainly in the old days, even as recently as 1997, the winter got cold enough that most of the precipitation fell as snow as the winter progressed. You can see in the 1997 the very nice "spring runoff" bump in the reservoir. That bump represents water stored as snow, and the flood diagrams assume that historic cycle, a cycle which is increasingly rare.
The prescriptions are predicated on the idea that the "conservation pool" is sufficient to store any additional inflow and avoid what happened, and recall that what happened is that they filled the reservoir to the flood control limit but were unable to raise the outflow sufficiently high to compensate for the next storm.
This is an important point, the dam was built to provide a fixed "conservation pool", which is basically the height of the spillway gate. And this was designed with the data they had on hand at the time.
Flood control, however, means reducing the dam capacity during periods of high inflow. And if you unlucky, this could mean you miss out on storing water, water which can be sold, and also used to generate electricity that could be sold... so there is an inherent conflict of interest between the flood control operations of the dam, and the water storage operations.
This bit them big time on the last storm. The flood control diagram doesn't make use of the fact that we have a 5 day storm coming in...
here is the forecasted flow rate ranges for the next 10 days:
from http://www.cnrfc.noaa.gov/espTrace.php?id=ORDC1
the inflow from the last storm was 155497 cfs, and over 100000 cfs for 4 days...
this storm looks more like the early January storm which had 3 days around 90000 cfs, and filled to the flood control limit... so a lot of water...
my point is that this forecast is not used in make flood control decisions.
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Ken M
Mountain climber
Los Angeles, Ca
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Feb 16, 2017 - 09:30pm PT
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Back to the dam, any experts here want to chime in on the subject as to why the emergency spillway has nothing but dirt underneath it...
Remember that this was built back in the time of essential parity between the parties, both State and National.
These things are typically planned using the "lowest bidder" concept, which back then included significant graft and corruption.
On top of which, Repub always fought for the cheapest possible building costs (keep taxes low).
A great combination of factors that have led to inadequate engineering, inadequate upgrading, and inadequate testing of the actual built facilities.
What could go wrong???
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TLP
climber
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Feb 16, 2017 - 09:40pm PT
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Interesting thoughts, Ed, ones I agree with very much. I did notice that your previous contribution noted that their actions are determined by the past 6 weeks' data, not forecasts. It may well be that when the rules of the game were established, they were good with stream gauges and temperature, (in fact, probably had more of the former than we now do) so could be pretty solid about calculated inflow based on that data in hand. Short-/medium-term forecasts weren't nearly as good back a few decades as they are now.
Your last graph there from AFPS has a puzzling aspect which I could probably figure out by going there, but if you know the answer quickly, that would be dandy. The blue dots for "Dist Mean" are all well below the minimums, not to mention the range, SD, and max. Are those means for the date from the period of record?? Because they certainly can't be means of the forecast ranges. (Can they?)
FWIW - different subject here - California has always had periodic rain-on-snow events, ever since the first records and no doubt before there were numerical records, I'm sure there are anecdotal reports of them from say the mid-1800s. And some of those have been huge. The expectation is that we will henceforth be having more, and/or bigger rain-on-snow events. Formerly, these might have been discounted as being just the really rare oddball, and not adequately addressed in management prescriptions, but they're not, they're a regular thing.
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neebee
Social climber
calif/texas
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Feb 16, 2017 - 09:43pm PT
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hey there, say, all... just checking out, the shares, here...
say, labrat, :O
oh my, NEVER had heard of that...
terrible, :O (the dam) :(
though, thank you for sharing in the info...
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neebee
Social climber
calif/texas
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Feb 16, 2017 - 09:44pm PT
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hey there say, timid... thanks for the update...
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TLP
climber
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Feb 16, 2017 - 09:52pm PT
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Back to the dam, any experts here want to chime in on the subject as to why the emergency spillway has nothing but dirt underneath it...
There is more to it than stated by Ken M. Whatever the case was in the 1960s when it was built is not that relevant. This issue was raised by written public comments during relicensing in roughly 2005, maybe even an appeal or litigation (not sure about either of those). FERC ignored those comments, without a doubt because the big water customers, like LA MWD, didn't want to pay the cost of building a proper armored auxiliary spillway, and they have clout or buddies. Now all state taxpayers, not just those water users, will pay for both the emergency repairs and new spillways afterward.
That said, there are other big dams with unarmored emergency spillways: New Don Pedro and/or New Melones, maybe others. I bet people will be taking a close look at those, as well as the primaries, this summer.
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 16, 2017 - 10:08pm PT
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Your last graph there from AFPS has a puzzling aspect which I could probably figure out by going there, but if you know the answer quickly, that would be dandy. The blue dots for "Dist Mean" are all well below the minimums, not to mention the range, SD, and max. Are those means for the date from the period of record?? Because they certainly can't be means of the forecast ranges. (Can they?)
the blue dots and red bars are the mean and standard deviation for the forecast flow rates... for some reason the plot I originally put up was a bit wonky... I reran the forecast and got the plot currently on that post.
this makes much more sense as the means are within the min/max limits...
not sure what happened before.
as for weather records before 1910, I suspect that there doesn't exist enough information to infer the watershed area for the Feather River system. I haven't looked though. But certainly not much information before the mid-1800s.
That situation has also changed, see for instance:
Prolonged California aridity linked to climate warming and Pacific sea surface temperature
How unusual is the 2012–2014 California drought?
Anthropogenic warming has increased drought risk in California
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john hansen
climber
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Feb 16, 2017 - 10:21pm PT
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I was kind of unsure to post this, because I dont have the link where I saw it, but I had read that the emergency spill way was built on - "mechanically compacted soil".
If you look at the photos of the erosion below the E spillway it looks as thou this could be the case. Soil with cobbles , the same as the main dam.
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August West
Trad climber
Where the wind blows strange
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Feb 16, 2017 - 11:26pm PT
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The prescriptions are predicated on the idea that the "conservation pool" is sufficient to store any additional inflow and avoid what happened, and recall that what happened is that they filled the reservoir to the flood control limit but were unable to raise the outflow sufficiently high to compensate for the next storm.
Is the above in reference to what just happened or '97?
For what just happened, the primary thing that wrong is that the main spillway had an unexpected problem that led to the events that caused the flow over the emergency spillway. Without the erosion on the main spillway, they could have released enough water through the main spillway and nobody on ST (or CA media) would be talking about Oroville.
I agree they should redo their operation books, take into account that rain is more likely than it used to be and take into account that 5 to 10 day weather forecasts are, way, way better than they were 20 or 30 years ago.
But farmers have huge political clout and there is hell to pay when CA goes into a drought with full reservoirs. If a drought started after a spring in which they lowered the reservoirs but the rain veered too far off track...
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Ed Hartouni
Trad climber
Livermore, CA
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Feb 16, 2017 - 11:29pm PT
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TT, the flood control diagram says they have to get the capacity down to 2780000
Is the above in reference to what just happened or '97?
what just happened
I agree (and said up thread) that there are limits to how much they can release down stream... but the point of the flood control diagrams are that they prevent floods from happening...
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August West
Trad climber
Where the wind blows strange
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Feb 16, 2017 - 11:41pm PT
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There seems to be some misunderstanding of the Sacramento releases from Keswick Dam on Lake Shasta and it's relation to the Feather River.
Currently, Keswick Dam is releasing the maximum that can be sent downstream. The Sacramento is at or near flood stage in most of Tehama County..
The Feather River joins the Sacramento near the little farm town of Nicholas, off the Garden Highway about 30 or so miles upstream of Sacramento.
This meeting of the rivers may become the new problem area if the Sunday, Monday rain event meets or exceeds precipitation predictions.
They have been dropping the water level at Oroville and Shasta still has some space in it. None of the people I've talked to informally have expressed any concerns about the storms being big enough to threaten anything downstream of where the Feather comes into the Sacramento.
The main question seems to be is how much will have to be released down the main spillway and how much damage it will cause.
The damage to the emergency spillway certainly spooked them (as it should). Which is the silver lining in all of this. The damage to the main spillway created a situation where a relatively small flow went over the emergency spillway and showed that there is a real problem that needs fixing. Without the original damage, the emergency spillway would, presumably, have continued to be ignored and some day in the future its first use might have been at a much higher flow with a catastrophic outcome.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 16, 2017 - 11:42pm PT
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TT, the flood control diagram says they have to get the capacity down to 2780000
at 80K cfs that's ~48 hours to achieve the flood mitigation target before the pineapple expess arrives
looks like there could be some flooding
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rick sumner
Trad climber
reno, nevada/ wasilla alaska
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Feb 16, 2017 - 11:52pm PT
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With what we can now confidently reconstruct of weather extremes of the past, sometimes thousands of years, dam construction, maintenance, and eventual deconstruction and replacement is a necessary place to employ a healthy dose of the precautionary principle. One major failure can negate decades of benefits. At this point I hope your governor can put his toy train away long enough for the neccessary investment to keep further potentially catastrophic existing infrastructure failure at bay. Maybe the residents should demand it.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 17, 2017 - 12:11am PT
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looks like the pineapple express arrives Sunday night carrying 10 inches in ~ 24 hrs
DWR plans to reduce Outflow to 60K cfs on Saturday. My guess is that they've decided to risk some flooding rather than risk further damage to the main spillway knowing full well that any use of the emergency spillway is to be avoided. If the main spillway exhibits additional signs of damage (e.g., significant headward erosion or fracturing of the surrounding bedrock) during the next couple of days, that will probably trigger another evacuation.
http://www.latimes.com/local/lanow/la-me-ln-oroville-weather-forecast-20170216-story.html
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