As Gretchen Weber reported on KQED's Climate Watch blog Friday, the U.S. Geological Survey has released a report underscoring storms of near-biblical proportions that have over the course of millenia repeatedly hit the Sacramento Valley, turning it into what Weber calls "an inland sea." The USGS calls this catastrophic potentiality the "ARkStorm Scenario," which, Weber writes, 'comes from the term 'atmospheric rivers,' meteorological phenomena that draw moisture from the tropics and funnel it into temperate regions." (Though associations with Noah can't be unintentional, I'm thinking.)
According to geological evidence cited in this USGS Multihazard Demonstration Project report, just such a tempest has pounded the area in the above-mentioned years. If you don't believe it, check out historic flood photos from 1862 Sacramento, embedded in this Sacramento Bee article about last week's Cal State Sacramento conference on the subject:
California has more risk of catastrophic storms than any other region in the country – even the Southern hurricane states, according to a new study released Thursday...
In the study, researchers used computer models and a composite of three historical storms to estimate a worst-case event: a torrent of tropical rain for nine straight days.
It amounts to a 500-year storm. In the lingo of disaster managers, that does not mean it happens only once every 500 years, but that it has two-tenths percent chance of occurring in any given year.
The Central Valley and the Sacramento region are likely to suffer the worst effects because they lie within a funnel for the state's biggest rivers.
Here's a video on ARkStorm put out by USGS, replete with enough scary music and graphics to make the producers of An Inconvenient Truth take note.
On Friday, Gretchen Weber interviewed USGS Director Marsha McNutt about the project. McNutt says the state is not yet ready to cope with this level of storm, but that the agency's work on earthquake preparedness can serve as a model for how to gradually update disaster planning for such a catastrophe.