I have read about a super wet year in the 1850s (?) that caused tremendous flooding in the entire central valley that lasted for months — turned it north and south into a giant inland sea.
If California were to have that sort of year again, do you think (as I do) that the majority of these structures built in the era prior to the last 40 years will stand the test?
Hi KC Burke,
Yes, there was an event that went for 40+ days of rain & 10 to 15 ft of snow up in the mountains that combined to yield a “megaflood”.
Scientists have released research publications on this phenomenon and they dubbed it “ARkStorm” (play on the wording of Noah’s Ark).
https://pubs.usgs.gov/of/2010/1312/of2010-1312_text.pdf
Below is an excerpt as the doc is sizable (download).
Notice the 2nd paragraph in the excerpt.... Then think of the current situation. There is more than 10 to 15 ft of snowpack. The recent wave after wave of “atmospheric rivers” inundating California... hmmm sounds like the same lurking scenario of water volumes.
Oroville Dam Specifications’ hydrological flow references, regarding floods, are in the upper right corner. I believe the larger numbers of “standard project flood” to “Spillway design flood” were intended to handle the worst case scenario encountered in the winter of Dec 1861-Jan 1862 - even if these cfs flow numbers are not present (they may have estimated that megaflood cfs flow for the Feather River basin).
== excerpt:
The hypothetical storm depicted here would strike the U.S. West Coast and be similar to the intense California winter storms of 1861 and 1862 that left the central valley of California impassible. The storm is estimated to produce precipitation that in many places exceeds levels only experienced on average once every 500 to 1,000 years.
Extensive flooding results. In many cases flooding overwhelms the state’s flood-protection system, which is typically designed to resist 100- to 200-year runoffs. The Central Valley experiences hypothetical flooding 300 miles long and 20 or more miles wide.
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