California Drought

[dmccarty]

If I followed all the developments correctly, if that concret barrier falls, only the top 20-30 ft of the lake would drain.

Correct, but that top 20-30 feet is a BUNCH of water that would go downstream. And what kind of erosion would take place when that volume of water went over the embankment. Methinks the lake would loose more than 30 feet of water and that would be a disaster.

Later,
Dan

 

[coldsteelva]

I believe that would be 30 feet by 16,000 acres of water. Not a paltry amount of water.

 

[houstonscott]

I believe that would be 30 feet by 16,000 acres of water. Not a paltry amount of water.

The hole undermined is is another 30' below bottom of weir. Because is next to spillway it might be just washed away too.

 

[turnkey4099]

Correct, but that top 20-30 feet is a BUNCH of water that would go downstream. And what kind of erosion would take place when that volume of water went over the embankment. Methinks the lake would loose more than 30 feet of water and that would be a disaster.

Later,
Dan

Yes, that would be a real disaster. But if the dam itself were to wash out that would be a DISASTER SQUARED. From the beginning there have been wild claims of he dam failing. It isn't.

 

[dragoneggs]

I believe that would be 30 feet by 16,000 acres of water. Not a paltry amount of water.

Unless paltry = 20 billion cu ft. (if my quick math is correct) :shocked:

 

[California]

Aczlan, RedNeckGeek, thank you for your rational analyses here and your intelligent contributions over on Metabunk.

 

[buckeyefarmer]

I've been enjoying the pics on metabunk.

 

[California]

Correct, but that top 20-30 feet is a BUNCH of water that would go downstream. And what kind of erosion would take place when that volume of water went over the embankment. Methinks the lake would loose more than 30 feet of water and that would be a disaster.

If I understand what I'm reading over on Metabunk today, they are running the damaged spillway at a high rate intended to get the lake level down and provide capacity for the storm that is beginning now.
Oroville Dam Spillway Failure | Page 16 | Metabunk
So ideally water won't go over the emergency spillway in the near future while they are repairing erosion damage there and fortifying the discharge area.

Meanwhile there is concern whether the damaged primary spillway is continuing to erode. One theory is its floor collapsed where it gets steeper (halfway down) due to conditions beneath it at that location, or possibly due to the physics of this change in pitch, and if those are primary causes then migration of the damage upstream may be minimal.

The moderator on Metabunk has started a new thread focusing on just the spillway:
https://www.metabunk.org/oroville-dam-spillway-failure.t8381/page-15#post-200468

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I'm impressed with Metabunk because they are actively countering the fear/uncertainty/ doubt some others are bringing to this event. "The sky is falling!! Buy prepper supplies/firearms/gold coins from our advertisers right now while you can!! Operators are standing by to take your money!! :laughing:

 

[buckeyefarmer]

They have shown the main spillway has not gotten worse in the last couple days of high discharge. At current discharge rate they expect lake to still decrease with the current rain coming in.
They also want to clear debris backing up water to the power plant.

 

[dragoneggs]

The moderator on Metabunk has started a new thread focusing on just the spillway:
Oroville Dam Spillway Failure | Page 15 | Metabunk

=============
I'm impressed with Metabunk because they are actively countering the fear/uncertainty/ doubt some others are bringing to this event. "The sky is falling!! Buy prepper supplies/firearms/gold coins from our advertisers right now while you can!! Operators are standing by to take your money!! :laughing:

Yes, some good information over on Metabunk. Thanks for sharing. I do think it is understandable, that there is 'some' fear/uncertainity/doubt and that should be expected even though it seems the authorities are getting a handle on how to proceed in the near term to mitigate risk. As for those opportunists that are trying to scare folks into buying their products by touting dire straits... hopefully people will see through them and not over react. Prepping for a situation where you might be displaced from your home for a while does seem prudent though even if it is not likely considering the situation.

 

[downsizingnow48]

Meta bunk is commendably focused on empirical practical circumstances and avoids the foolish emotional blather that infects most forums.

 

[NoTrespassing]

'Biggest storm of winter' to unleash flooding rain in California at week’s end

'Biggest storm of winter' to unleash flooding rain in California at week’s end


"The late-week storm has the potential to be the biggest of the winter in terms of rainfall and impact to much of Southern California," according to AccuWeather Meteorologist Jim Andrews.

The storm will bring enough rain and excess runoff to cause flash flooding, which can cause major delays for motorists. Along with the heavy rain will be the potential for mudslides in some neighborhoods, especially in recent burn scar locations.


"We expect 3 to 6 inches of rain to fall in the lowlands along the coast and over the Los Angeles basin," according to AccuWeather Senior Meteorologist Ken Clark. "From 6 to 12 inches of rain is likely below snow levels in the mountains, especially along the south-facing slopes."

In the Los Angeles and Santa Barbara, California areas, much of this rain may fall in 24 hours from early Friday morning through Friday night. In San Diego, the heaviest rain will fall Friday evening into Saturday morning.

Good Luck CA
Kevin

 

[buckeyefarmer]

Hopefully the heavier rain stays south then.

 

[k0ua]

Good luck out there guys..stay safe..

 

[California]

Thanks k0ua, from everyone out here.

 

[ForestGrump]

My concern with this issue is that the geology of the dam, the spillway and the emergency spillway seem to be conflicted. It has been stated that these were built on a solid rock face. Evidently not in the case of the two spill ways, they eroded overnight. That's not solid rock. So what is the dam built on if the spillways were not built on rock. It is my opinion the geologic studies of the dam complex are suspect. I would re-evaluate the old studies and to conduct new studies. Especially since a compression earthquake has already occurred in the immediate area.

Face it, mistakes have been made both in the geology and in the construction of the dam resulting in two rather massive failures.

The dam in Big Bear is 100 years old. It was retrofitted just prior to the Landers/Big Beartwin quakes in '92 and then again after the quakes. It is now designed I believe to withstand an 8.5. It is time to do a thorough review of that dam, its geology and its construction based on current technology.

 

[aczlan]

My concern with this issue is that the geology of the dam, the spillway and the emergency spillway seem to be conflicted. It has been stated that these were built on a solid rock face. Evidently not in the case of the two spill ways, they eroded overnight. That's not solid rock. So what is the dam built on if the spillways were not built on rock. It is my opinion the geologic studies of the dam complex are suspect. I would re-evaluate the old studies and to conduct new studies.

Time will tell. When they put in the emergency spillway, they ripped down 10 feet into the rock to get to "suitable rock" for the base of the emergency spillway. That rock has not eroded, nor has the erosion reached the base of the emergency spillway.

On the main spillway, it eroded to a point, then it held up to 100,000cfs (as much water as flows over Niagara Falls every second) for 5 days before they started throttling it back today.
I suspect that the under-slab drainage for that section failed which let the fill wash out and leave the concrete unsupported. In the construction notes, they also talked about needing a different anchor system for some sections of rock (the orangeish rock) as it was weaker.

Face it, mistakes have been made both in the geology and in the construction of the dam resulting in two rather massive failures.

Massive, perhaps but not fatal to that dam and not sufficient to cause a complete dam failure like some of the chicken little crowd would have you believe.

Aaron Z

 

[coldsteelva]

The new/repaired/rebuilt spillway needs to be supported by poured columns not just the local geology (more like an aqueduct than a rain gutter)

 

[houstonscott]

Time will tell. When they put in the emergency spillway, they ripped down 10 feet into the rock to get to "suitable rock" for the base of the emergency spillway. That rock has not eroded, nor has the erosion reached the base of the emergency spillway. On the main spillway, it eroded to a point, then it held up to 100,000cfs (as much water as flows over Niagara Falls every second) for 5 days before they started throttling it back today. I suspect that the under-slab drainage for that section failed which let the fill wash out and leave the concrete unsupported. In the construction notes, they also talked about needing a different anchor system for some sections of rock (the orangeish rock) as it was weaker. Massive, perhaps but not fatal to that dam and not sufficient to cause a complete dam failure like some of the chicken little crowd would have you believe. Aaron Z

I haven't seen one post predicting the dam failing. There are many concerns that the lake could indeed drain from a failure of the emergency spillway, and cut a new channel right there.

 

[TemporaryKubotaOwnerMark]

It is my opinion the geologic studies of the dam complex are suspect. I would re-evaluate the old studies and to conduct new studies.

Agreed. We have learned a lot since those studies were done. It's just prudent to apply that knowledge by re-examining the work.

The dam in Big Bear is 100 years old. It was retrofitted just prior to the Landers/Big Beartwin quakes in '92 and then again after the quakes. It is now designed I believe to withstand an 8.5. It is time to do a thorough review of that dam, its geology and its construction based on current technology.

Just on the north side of Landers is a batholith which presents as a hill rising above the town. It's rather like an iceberg in that most of it is underground. IIRC it's around 1500 feet above the surrounding terrain, so that's a pretty big rock. I was present when a geology team from one of the big-name universities (can't remember if it was UCLA or USC) measured it to see how the quake affected it. It had moved 18 feet south and 12 feet up, IIRC. The terrain north of town showed "stretch marks", the classic horror movie cracks in the earth that swallow cars. Well, none of them was quite big enough to swallow a car, but several were big enough for a car to fall partially in. I saw them a few days later when they had gotten filled in to make the highway passable.


All that to say, given the right earthquake at the wrong place, no dam will stand. There is just too much energy involved. We should do all we can, but "all we can" has to include the recognition than an earthquake can completely take out any dam in just a few minutes.