You’ve heard of The Big One. Now meet The Other Big One – a massive statewide flooding catastrophe that could cripple California for months or years.
Researchers think a megaflood is just as likely to hit the state as a 7.8 magnitude earthquake, and has the potential to cause three times as much damage. San Diego County alone would suffer $25 billion in losses under a doomsday “atmospheric river” scenario created in 2011 by dozens of researchers during which a series of heavy storms would slam the northern and central parts of the state.
Nearly the entire neighborhood of Mission Beach would under water. Large numbers of residents would lose power and sewage service. Landlines, internet connections and cell phones could stop working for 15-20 percent of customers. And both I-15 and I-5, the two main routes to the north, wouldn’t return to full service for months.
The scenario assumes that California would be hit by a series of storms just as it was during the Civil War when the Great Flood of 1861-1862 boosted L.A.’s annual rainfall to 66 inches, forced the relocation of the state capital and produced a massive inland sea in the Central Valley.
Does the scenario the researchers modeled still hold up six years after it was released? Absolutely, the researchers say, with one putting it this way: “This past winter reassured me of this again and again.”
Michael Dettinger, a research hydrologist with the U.S. Geological Survey and one of the authors of the megaflood report, said it’s clear that climate change is exacerbating the risk of a such an event. Nonetheless, the 2011 report doesn’t appear to have focused many minds or prompt any major changes in how we prepare for disasters in California.
We Stand Up for You. Will You Stand Up for Us?
As is the case in Houston, Much of San Diego's vulnerability is due to landowners and developers pushing to allow building in floodplains and elected officials allowing it to occur. Much of Mission Valley should never have been developed, certainly not without floodways and bridges. As a responder to major flooding events in the 1980s and 1990s, it was quite evident to me that most of the places that flooded were places that should not have been inhabited. But because major flood events occur irregularly, memory fades.
Every flood spawns at least some new preparations for the next flood. Some big and some small improvements add up over time and make us less likely to suffer the same results. For example since 1800s we have built dozens of reservoirs in San Diego County that can help moderate the effect of heavy storms. These structural changes will slow the water into many of our valleys. There are some areas in SD County that are still very prone to flooding and that just can’t be improved. Sorry about that.
Also we have done some truly idiotic stuff. The flood channel is Mission Valley has been vastly overbuilt, and flood levels that happened as recent as the 1960s-1970s, would cut off access to many homes and businesses and put many of them underwater if they happened now.
I hope that if there is a big flood that we will NOT allow rebuilding in flood prone areas, and will learn the lesson of where we should and should not build.
Here's what the 1984 book "Sea Cliffs, Beaches, and Coastal Valleys of San Diego County, Some Amazing Histories and Some Horrifying Implications" says:about the "Noachian Deluge" of 1861-1862:
"The great Sacramento and San Joaquin valleys of California were turned into a lake abut 200 miles long and 20 to 60 miles wide.:"
"In February 1862, the Los Angeles, San Gabriel, and Santa Ana rivers merged. Government surveys at the time indicated that a solid expanse of water covered the area from Signal Hill to Huntington Beach a distance of approximately eighteen miles."
"In San Diego the flooding coincided with a storm at sea, which backed up the water running into the bay from the San Diego River. As a result, the river cut a new channel into San Diego Harbor."
Although the probability of a similar deluge may be one in 500 to one in 1000 in any one year, the probability of getting two such storms back to back in two years is much reduced. It's like tossing a penny. Yes, it's a one in two chance of either side of the coin turning up. But two tosses in
a row getting the same side is one in four. Similarly for a catastrophic storm.
This is a timely and sobering article for all to read.
Since you can't trust local government, it's down to the consumer. You want to live on a sandstone bluff overlooking the ocean?
Don't whine when the bluff crumbles into the sea.
Want to live at sea level near water?
Don't whine if you get flooded out. You knew the job was dangerous when you took it, Fred.
And if you buy a home on a pad scraped out of a hillside?
@barb graham or continue pouring billions of dollars in new structures at the small single runway "international" airport - which is @14' ASL.
Guess that's just another catastrophe that I'll have to add to my nightmare list. I don't think it will outrank homeless, who are invading us like hordes of zombies, or N. Korea taking us out because of our military facilities. It's good to be old...