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halfmanhalfbronco

Large part of California could become a vast inland sea in the next 40 years.

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Climate change has increased the chances of a mega flood 200%.  100 inches of rain could fall in a very short period of time.  This last happened in 1846.

https://www.science.org/doi/10.1126/sciadv.abq0995

"These massive floods, which experts say would turn California's lowlands into a "vast inland sea," might have previously happened once in a lifetime in the state. But experts say climate change is increasing the likelihood of these catastrophic disasters, causing them to occur more like every 25 to 50 years."

@SJSUMFA2013 still want to secede?  

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On 8/12/2022 at 3:05 PM, halfmanhalfbronco said:

Climate change has increased the chances of a mega flood 200%.  100 inches of rain could fall in a very short period of time.  This last happened in 1846.

https://www.science.org/doi/10.1126/sciadv.abq0995

"These massive floods, which experts say would turn California's lowlands into a "vast inland sea," might have previously happened once in a lifetime in the state. But experts say climate change is increasing the likelihood of these catastrophic disasters, causing them to occur more like every 25 to 50 years."

@SJSUMFA2013 still want to secede?  

Sort of. 

First of all, it (being the "inland sea" thing) last happened in the early 1860s not 1846.

Second, it would create a temporary inland sea in some places, which would be mitigated to some extent by existing infrastructure. The infrastructure has already mitigated it in past versions of these massive precipitation events. The water would run off pretty quickly in relative terms, though causing a lot of damage. 

These types of events have already happened since then... 1997 being the last real big one, but there were also some in the late 60s and I think one in the 80s?. The question is if they become more frequent or if they become more intense. 

I wouldn't mind a couple in the next 20 years or so. We need to recharge some of our aquafers and get the suitcase farmers out of here. 

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On 8/12/2022 at 4:16 PM, smltwnrckr said:

Sort of. 

First of all, it (being the "inland sea" thing) last happened in the early 1860s not 1846.

Second, it would create a temporary inland sea in some places, which would be mitigated to some extent by existing infrastructure. The infrastructure has already mitigated it in past versions of these massive precipitation events. The water would run off pretty quickly in relative terms, though causing a lot of damage. 

These types of events have already happened since then... 1997 being the last real big one, but there were also some in the late 60s and I think one in the 80s?. The question is if they become more frequent or if they become more intense. 

I wouldn't mind a couple in the next 20 years or so. We need to recharge some of our aquafers and get the suitcase farmers out of here. 

 

What would the cost to infrastructure and lives be do you think?

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The loop in this thread looks pretty devastating @smltwnrckr

https://www.cnn.com/2022/08/12/weather/california-megaflood-study/index.html

"

The area with the most destruction would be the Central Valley of California, including Sacramento, Fresno and Bakersfield, the study's authors project. The Central Valley, roughly the size of Vermont and Massachusetts combined, produces a quarter of the nation's food supply, according to the US Geological Survey.
A flood with the size to fill this valley has the potential to be the most expensive geophysical disaster to date, costing upwards of $1 trillion in losses and devastating the state's lowland areas, including Los Angeles and Orange counties, according to the study.
That would be more 5 times the cost of Hurricane Katrina, the current costliest disaster in US history."
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On 8/12/2022 at 3:17 PM, halfmanhalfbronco said:

 

What would the cost to infrastructure and lives be do you think?

Oh, I dunno. It depends where it happened, how it happened and what infrastructure failed. I'd have to look at what happened in 1997 and extrapolate. Lot of ag land would be inundated, a lot of cows would die. 

The question really is whether the intensity of the event would cause the infrastructure to fail. If you got multiple dams to fail and multiple levee breaks, it would be a bad bad deal. 

It's definitely a concern, especially considering that a lot of Valley development has happened in floodplains. But the "vast inland sea" thing is more of a headline grabber than an accurate portrayal of what it would be like. 

 

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On 8/12/2022 at 3:20 PM, halfmanhalfbronco said:

The loop in this thread looks pretty devastating @smltwnrckr

https://www.cnn.com/2022/08/12/weather/california-megaflood-study/index.html

"

The area with the most destruction would be the Central Valley of California, including Sacramento, Fresno and Bakersfield, the study's authors project. The Central Valley, roughly the size of Vermont and Massachusetts combined, produces a quarter of the nation's food supply, according to the US Geological Survey.
A flood with the size to fill this valley has the potential to be the most expensive geophysical disaster to date, costing upwards of $1 trillion in losses and devastating the state's lowland areas, including Los Angeles and Orange counties, according to the study.
That would be more 5 times the cost of Hurricane Katrina, the current costliest disaster in US history."

The flood wouldn't fill the valley. It would flood a bunch of lowlands in parts of the valley and probably to do Sacramento what Katrina did to NO.

Look at the wording... it says the kinds of floods that occur once a lifetime would now occur more frequently. But there have not been any floods that have filled the valley in basically two lifetimes. And even then, the flood of 1862 and generally valley flooding in the middle to late 19th century was exacerbated by the hydraulic mining in the Sierras. That flood is the high water mark (pun intended) for floods in CA after European arrival. The question is whether that level flood is the kind we see more of, or if we see floods like 1997 happening every 10 years or so. And if its the earlier, the question is what the infrastructure does to mitigate it, as well as the fact that entire mountainsides are not flowing down with the floodwaters as was the case in the 1860s. 

We have to start thinking about this in terms of development planning and infrastructure in CA, definitely. But there's a level of alarmism in this that should be discarded in that planning. 

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On 8/12/2022 at 3:25 PM, ridgeview2 said:

On the bright side, at least we will finally be out of a drought. :shrug:

I hate to be that guy...

But, actually, the flood of 1862 followed and then was followed by some of the most brutal drought years in the history of the state. 

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I'll take a look at this study more carefully soon. But one of my main questions is how the lower volume of snowpack squares in all of this. These huge flood events happen when you get a very cold, snowy early winter which builds up the snow pack in the sierras, and then an extended series of warmer atmospheric rivers coming through which not only drops a sh*tload of rain but also melts a sh*tload of snow very quickly below like 6000 or 7000 feet. You need both for these mega floods to happen. But if we are going to have diminishing snowpack below 6,000 feet or so, you're taking an important part out of that equation. 

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On 8/12/2022 at 4:01 PM, CPslograd said:

https://www.tularebasinwatershedpartnership.org/history.html
 

Largest lake by surface area west of the Mississippi.

Build more water now to prepare for the 100 year flood.😀

An event like that impacting the Southern sierras would fill Tulare and Buena Vista lake basins first. For the people outside of those basins, it would be the upside of the environmental desecration that came out of draining our lowlands. 

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On 8/12/2022 at 3:43 PM, smltwnrckr said:

I hate to be that guy...

But, actually, the flood of 1862 followed and then was followed by some of the most brutal drought years in the history of the state. 

yikes-rachel-dratch.gif

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On 8/12/2022 at 3:23 PM, smltwnrckr said:

Oh, I dunno. It depends where it happened, how it happened and what infrastructure failed. I'd have to look at what happened in 1997 and extrapolate. Lot of ag land would be inundated, a lot of cows would die. 

The question really is whether the intensity of the event would cause the infrastructure to fail. If you got multiple dams to fail and multiple levee breaks, it would be a bad bad deal. 

It's definitely a concern, especially considering that a lot of Valley development has happened in floodplains. But the "vast inland sea" thing is more of a headline grabber than an accurate portrayal of what it would be like. 

 

Not to mention the state has significantly upgraded their reservoir infrastructure to be able to handle more extreme precipitation events.   Folsom Dam protects much of Sacramento on the American River and it has been significantly updated with the ability to release water in anticipation at a much higher rate.   

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On 8/12/2022 at 5:00 PM, sactowndog said:

Not to mention the state has significantly upgraded their reservoir infrastructure to be able to handle more extreme precipitation events.   Folsom Dam protects much of Sacramento on the American River and it has been significantly updated with the ability to release water in anticipation at a much higher rate.   

True, tho there are some. pretty gnarly accounts of how close things got to being overwhelmed on the American River system at folsom and elsewhere in 1997. So catastrophic failure would change the calculus.

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On 8/12/2022 at 4:05 PM, halfmanhalfbronco said:

Climate change has increased the chances of a mega flood 200%.  100 inches of rain could fall in a very short period of time.  This last happened in 1846.

https://www.science.org/doi/10.1126/sciadv.abq0995

"These massive floods, which experts say would turn California's lowlands into a "vast inland sea," might have previously happened once in a lifetime in the state. But experts say climate change is increasing the likelihood of these catastrophic disasters, causing them to occur more like every 25 to 50 years."

@SJSUMFA2013 still want to secede?  

Good. Fresno needs a thorough cleansing 

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On 8/12/2022 at 4:26 PM, smltwnrckr said:

An event like that impacting the Southern sierras would fill Tulare and Buena Vista lake basins first. For the people outside of those basins, it would be the upside of the environmental desecration that came out of draining our lowlands. 

Sometimes in the spring you get a feel for how spectacular it must have been here at certain times of the year.  
 

 

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On 8/12/2022 at 6:56 PM, CPslograd said:

Sometimes in the spring you get a feel for how spectacular it must have been here at certain times of the year.  
 

 

I've been more and more getting into finding wetland and grassland areas in the valley and visiting in spring and winter. Underrated cool places out there.

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