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August West
Trad climber
Where the wind blows strange
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Feb 19, 2017 - 09:59pm PT
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John M, that metabunk link had some good info.
Thanks
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healyje
Trad climber
Portland, Oregon
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Feb 19, 2017 - 11:11pm PT
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I would have expected more like 3-4' thick side walls a couple of feet taller and the spillway bed to be 2-3' thick with no soil under it anywhere and anchored to bedrock with piers. The existing spillway bed looks about as thick and robust as the average Las Vegas subdivision scrape-and-pour slab jobs.
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clinker
Trad climber
Santa Cruz, California
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Feb 20, 2017 - 06:23am PT
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Scott Stine, a professor of geography and environmental studies at Cal State East Bay, has spent decades studying tree stumps in Mono Lake, Tenaya Lake, the Walker River and other parts of the Sierra Nevada.
Excerpted from an article citing his work, published in the San Jose Mercury News in 2014:
Through studies of tree rings, sediment and other natural evidence, researchers have documented multiple droughts in California that lasted 10 or 20 years in a row during the past 1,000 years -- compared to the mere three-year duration of the current dry spell. The two most severe megadroughts make the Dust Bowl of the 1930s look tame: a 240-year-long drought that started in 850 and, 50 years after the conclusion of that one, another that stretched at least 180 years.
Looking back, the long-term record also shows some staggeringly wet periods. The decades between the two medieval megadroughts, for example, delivered years of above-normal rainfall -- the kind that would cause devastating floods today. But Stine, who has spent decades studying tree stumps in Mono Lake, Tenaya Lake, the Walker River and other parts of the Sierra Nevada, said that the past century has been among the wettest of the last 7,000 years.
Moral of the story(study) the trees survived. Think like a tree California!?
Yesterday we stopped by a friends house. While we were there his renter called, all excited over the neighbor below cutting down trees on the bottom of the property. For some background on this, several of the many trees on the property have fallen down recently, one destroying another neighbors fence, so when this guy asked to "take down a couple trees", my friend gave him permission.
The excited and concerned renter, "Hey, that's a lot of trees you're cutting down!"
Neighbor, "I am trying to get some winter sun to shine on my property."
Renter, "Then you should move to Arizona."
Oh boy.
:)
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justthemaid
climber
Jim Henson's Basement
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Feb 20, 2017 - 07:16am PT
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This is a great thread everyone. I read it with my morning coffee:)
@ Clinker^ Bristlecone tree ring data confirms all that BTW^^^ Right at the end of the season we installed a 30' long interpretive display up at the Schulman Visitor's Center recording 8000 years of ring widths. Extreme drought and rain periods are the norm over the millennias and the trees always recover eventually.
It's all very dramatic to us short-lived humans.
A related side to your second story- A friend in LA has a back yard with a steep hillside. The uphill neighbor sited a concern over a single dying tree (in a line of mature pine trees) on my buddy's side of the property line and asked if they could remove it. My buddy said "sure". Next thing - they came home one day and every single tree (living and dead) on the hill was removed.
Turns out the neighbor was putting in an infinity swimming pool and didn't want any trees blocking their view. ;(
Another "Oh boy"
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rottingjohnny
Sport climber
Sands Motel , Las Vegas
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Feb 20, 2017 - 10:02am PT
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Maid...that same thing happened to some friends except that no permission was granted....came home and their trees were gone....sued and got cashed out...
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neebee
Social climber
calif/texas
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Feb 20, 2017 - 12:09pm PT
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hey there say, werner... thanks for the update...
i was just going to try and see what was up...
thank you... helped so much!
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 20, 2017 - 12:33pm PT
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Here's the latest data from the CDEC website...
Storage Capacity (2,794,558 Ac ft) & Water Level (848.97 ft) holding steady. (Flood control levels SC = 2,780,000 Ac Ft & WL = 850 ft).
1 inch of rain in the last 12 hours. Inflow (57,081 cfs) just below Outflow (59,899 cfs) at the main spillway.
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john hansen
climber
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Feb 20, 2017 - 07:57pm PT
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Here is a video showing the damage under the emergency spillway the day it started over flowing.
So much erosion at only 12500 cfs .
You can skip the first 30 seconds if you want to get right to the scary stuff.
Imagine if that thing had 40,000 or even 60,000 cfs going over it..
Thanks , Werner and Jstan for the links above, looks like they have done a lot but they still have a lot of work to do to protect it so they can make it to summer.
It looks like they have lowered the water behind the dam enough to handle this storm.
https://www.youtube.com/watch?v=vzcQjvH3idU
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Don'tKnowHim
Social climber
California
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Feb 22, 2017 - 07:04pm PT
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It is my understanding that "water bonds" were issued under both "Arnold" and ol' uncle Jerry, yet the money was never spent. Where is that money now?
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 28, 2017 - 07:05pm PT
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This drone video really shows the damage to the main spillway and the underlying, exposed bedrock, now that all the soil and "soft" bedrock has been removed...
[Click to View YouTube Video]
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Reilly
Mountain climber
The Other Monrovia- CA
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Feb 28, 2017 - 07:14pm PT
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This will be the new version of "The Money Pit".
"How long?"
"Two weeks!"
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Feb 28, 2017 - 08:50pm PT
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t-tradster what do you make of those freshly-exposed blue-green rocks that weather to red?
Here's my $0.02...
From what I can tell looking at the photos/videos and reading the literature without actually standing and looking at these fresh outcrops, it looks to me like a succession of island arc, volcanic (tholeiitic basalt) and volcaniclastic rocks that have been subjected to green schist facies metamorphism in a subduction zone. These rocks are part of the Smartville Ophiolite Complex (SOC), so they've undergone a series of tectonic events that took them from a deep marine trench environment to the sierra foothills. In addition, the SOC contains sheeted basalt dikes that presumably formed in a back arc spreading center and Granodiorite to Gabbro intrusions that are exposed just east of the metavolcanic rocks. You can see this relationship in the geologic map that I posted ^^^
I suspect that some of this material has been thermally and chemically altered by hydrothermal fluids along preferential pathways such as fracture systems or faults which has resulted in "weak or soft" bedrock that was vulnerable to mechanical and chemical weathering in the current environment. The red coloration in the rock, soil, and river, is most likely associated with iron oxides commonly associated with hydrothermal alteration and chemical weathering. Other minerals that could be present include chlorite (a clay mineral), talc, and possibly epidote. Some of the red coloration is due to iron oxidation in the bedrock matrix and some is due to staining of the bedrock rock from the adjacent, iron rich soil.
Although the bedrock is mostly dense and hard metamorphosed basalt, it is highly fractured, faulted, and in some places altered by hydrothermal fluids. My guess is that the main spillway was located on a major segment of bedrock that exhibited some of these weaknesses and became vulnerable to failure due to recent (last 10K years) weathering and then > 100K cfs water with tremendous erosive capacity.
http://gsabulletin.gsapubs.org/content/99/6/779.abstract
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stunewberry
Trad climber
Spokane, WA
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Feb 28, 2017 - 09:11pm PT
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Also interesting in the video as the flow just about stops how much erosion is actively happening along the right (facing downstream) side just below the lip. Lots of boulders still being dislodged and the water turns to mud, while the left side stays pretty much clear.
If there is that much active erosion going on as the flow stops, why didn't it erode all the way to the gates when the flow was 100K cfs?
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feralfae
Boulder climber
in the midst of a metaphysical mystery
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Feb 28, 2017 - 09:25pm PT
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Does the amount of erosion present any concerns about the integrity of the dam and its adjoining wings of native stone? Could that amount of erosion destabilize the physics of the configuration of the dam, especially with the level of the water behind it?
Am I worrying about nothing?
Thank you
feralfae
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