200-Year Flood in Calif. More Devastating Than Major Quake, USGS Says
By COLIN SULLIVAN of Greenwire
Published: January 20, 2011
A massive California rain event -- one expected to occur once every 200
years -- would far surpass destruction caused by a "Big One" earthquake,
causing more than $700 billion in damage and hobbling the state's
economy for decades, federal scientists are warning.
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The 1861-62 winter storm -- what scientists call an "atmospheric river storm" -- lasted for 45 days, producing precipitation that exceeded what some areas would experience once every 500 to 1,000 years. The flooding was so bad it reduced taxable land by a third, bankrupted the state government and left parts of the Central Valley looking more like an inland sea than the fertile farming area that today forms the backbone of the state's economy.
So USGS ran a scenario based on two recent storms, in 1969 and 1986, acting as if the accumulation of both occurred back to back. They found that rain would fall several feet deep, flood 9 million homes and probably overwhelm thousands of miles of levees and reservoirs.
USGS Director Marcia McNutt called the scenario "hypothetical but very plausible" given California's historical rainfall trends as well as the predicted effects of climate change, which some say could heighten the likelihood of widespread flooding. The point of the study, she said, is to help emergency planning efforts, as one dollar spent pre-emptively avoids hundreds spent later, she said.
"If we had a catastrophic disaster that takes down the California economy, that is a problem of national significance," McNutt said.
Lucy Jones, the primary architect of the ARkStorm test at USGS, added that the strength of such a storm is comparable to a intense hurricane but could leave behind far more damage as the atmospheric river keeps dumping water after a longer period. She noted that California is the only state outside of the hurricane-prone Southeast that tends to see rainfall as large as, say, 16 inches over a three-day period.
"This has to happen at some point," Jones said. "How prepared are we? That's essentially unanswerable. No flood control system can be or should be built to withstand every possible storm."
'Serious questions'
ARkStorm report in hand, USGS held a conference last week with the Federal Emergency Management Agency and the California Emergency Management Agency to sound the alarm and try to get parties thinking about what comes next.
Participants included more than 100 academics who participated in the process over the last two years, including researchers from the physical sciences as well as economists and social scientists.
The study itself looks at prehistoric geologic flood history in California alongside climate projections and flood mapping to try and point to the areas most likely to get hit hardest. Most of the damage would come from flooding, with as much as one-fourth of all houses in California damaged on some level.
The report notes an initial $300 billion estimate in damage would likely be exceeded as serious flooding hampers the Central Valley, Orange County, Los Angeles County, San Diego, the San Francisco Bay area and other coastal communities. The report says:
- Demand surge (an increase in labor rates and other repair costs) could increase property losses by 20 percent.
- Agricultural losses and other costs to repair lifelines, drain flooded islands and repair damage from landslides, brings the total direct property loss to nearly $400 billion, of which $20 billion to $30 billion would be recoverable through insurance.
- Power, water, sewer and other lifelines experience damage that takes weeks or months to restore.
- Flooding evacuation could involve 1.5 million residents in the inland region and delta counties, and business interruption costs could reach $325 billion in addition to the $400 billion in property repair costs, bringing ARkStorm's pricetag to the neighborhood of $725 billion.
Also detailed in the report are the first-ever landslide susceptibility maps for California, with hotspots identified along active coastal ranges, which have long been highly vulnerable to fatal slides in the middle of population centers. Environmental damage was also assessed, given the likelihood that a series of storms akin to 1861-62 would overwhelm wastewater treatment facilities, refineries, mining operations and other industrial sources.
Jones said the report, which did not look at effects on marine life, would at the very least bring severe runoff from industrial sources that would be carried into urban areas in a swirling mix.
"It's not something we usually talk about before lunch," she said. "It's an appalling mix."
Establishing a warning system
The conclusion for emergency planners is that such a scenario, many times worse than a Hurricane Katrina, would likely involve "decades of recovery" rather than months or years, said Nancy Ward of FEMA.
So the ARkStorm project reached out to emergency planners, businesses, universities, government agencies and others who prepare for major natural disasters, much like the "ShakeOut" earthquake scenario, published in May 2008 by USGS, looked at the effects of a 7.8 earthquake on the San Andreas Fault in Southern California.
"This is not just a 72-hour response, this is not just months of recovery," Ward said of the ARkStorm scenario.
While comparisons to earthquake planning are inevitable in California, the experts said the type of rainfall assessed in the report would trump the biggest of quakes, including the 1906 trembler in San Francisco that burned much of the city to the ground and killed more than 3,000 residents.
Mark Jackson, of the National Weather Service, noted that an 1861-level rain event would be felt up and down the state, while a repeat of the 1906 quake -- which measured about 8 on the Richter scale and ruptured 296 miles of the San Andreas Fault -- would be more localized, even if devastating.
ARkStorm, he said, "is not just what happens in your backyard. It would have a domino effect all the way through."
Jackson is currently engaged in trying to set up a warning system similar to the categories widely invoked to describe hurricane intensity. The floods in Southern California in December, for instance, measured about 20 "Mississippi atmospheric rivers" (about a Category 2 or 3 storm), while ARkStorm would easily surpass 50 Mississippis, he explained, comparing the amount of likely rainfall to the length and width of several Mississippi rivers.
A crucial challenge is simulating the network of remote sensors meteorologists use to detect wind speeds before a hurricane makes landfall. The same system does not exist in the Pacific to measure likely rainfall, but Jackson said NWS is working on new technologies.
"We're in the very early stages of a work in progress," he said.
Click here to link to the ARkStorm report.
Sullivan reported from San Francisco.
end quote from:
200-Year Flood in Calif. More Devastating Than Major Quake ...
Hopefully, this isn't the year for it. I was searching for news on flooding and when I put in "Flooding in California" into Google Search this was one of the articles that came up.
People on the Truckee River and near St. Helena which already received 9 inches of rain the other day are worried about flooding right now
Here is an article on the Truckee river plan:
If the Truckee River Floods, here's the plan
News10.net - 5 hours ago
An evacuation center for the Town of Truckee has been set up by the American Red Cross and emergency agencies in case the Truckee River ...
Truckee River expected to flood near Truckee; evacuation plan put in place for residents
5:16 PM, Dec 1, 2012 | 0 comments
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TRUCKEE, Calif. - An evacuation center for the Town of Truckee has been set up by the American Red Cross and emergency agencies in case the Truckee River floods Sunday morning.
The National Weather Service issued a flood warning for the Truckee River near Truckee and is scheduled to remain in effect from Sunday morning through Monday morning.
The Truckee River near Truckee reaches flood stage at
4.5 feet. According to the NWS, the river is expected to rise above
flood stage by Sunday morning and continue to rise to almost 7.7 feet by
late Sunday morning. The NWS predicts the river should fall below flood
stage in the Truckee area by Sunday evening.
The Red Cross, the Town of Truckee and the Nevada and
Placer County Offices of Emergency Service is established the
evacuation center, Nevada County Emergency Services Program manager
Victor Ferrera said. The center has been set up in the Administration
Building of the Tahoe Truckee Unified School District at 11603 Donner
Pass Road and is scheduled to open at 6 a.m. and remain open as long as
it is needed.
Emergency officials are advising residents, visitors and all motorists:
-
Not drive a vehicle into areas where the water covers the roadway. The water depth may be too great to allow your vehicle to cross safely
-
To pay special attention in areas beneath recent burn scars as these areas will be susceptible to debris flow
-
Residents in affected areas should take active precautions, monitor conditions closely and evacuate the area if needed
Sand and sandbags are available at the following locations near Truckee:
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Old Squaw Valley fire station, 1810 Squaw Valley Road
-
North Tahoe Fire Station 52, 288 North Shore Blvd, Kings Beach (Intersection of Hwys 267 & 28)
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Truckee: Truckee Fire Station 92, 11473 Donner Pass Road
-
Truckee Ranger Station parking lot, 10811 Stockrest Spring Rd
Sand and sandbags are also available at various
locations throughout Placer County, Nevada County, and Truckee. For a
complete listing, please visit the following website:
Make an evacuation plan- what to take, where to go, how to stay in touch
- If you think you might need to evacuate, go. If you delay, you will probably be trapped
- No matter what happens, stay out of the water. Debris in flood runoff and high flows make it extremely dangerous to attempt to retrieve objects or rescue people
- Stay calm, think clearly and be decisive
- When in doubt, call 911 and ask for help
If the Truckee River Floods, here's the plan
CBS Local- Flood warning in effect for Napa and St. Helena
Napa Valley Register - 4 hours ago2012-12-01T19:42:00Z 2012-12-01T21:27:59Z Update: Flood warning in effect for Napa and St. HelenaKERANA TODOROV and HOWARD YUNE Napa Valley ...Update: Flood warning in effect for Napa and St. Helena
Downtown Napa mostly expected to dodge bullet
SATURDAY - DECEMBER 1, 2012 - NAPA, CA - Pedestrians bustle past sandbags lining the facade of Yo'Belle yogurt shop on Main Street in downtown Napa on Saturday. Napans spent the day getting ready for more coming rains after a flood warning was issued early Saturday morning. After four straight days of already heavy rain, heavier rains are expected to sweep into the area on Sunday, pushing the Napa River to flood levels. Lisa James/Register
Updated at 7:42 p.m.: RiverPointe Napa Valley resort on Lincoln Avenue has been evacuated and 37 modular cottages moved.
The Napa River is projected to rise 2 feet above flood stage in St. Helena and near Oak Knoll Avenue on Sunday, but no major flooding is expected in downtown Napa, according to city officials.
The National Weather Service has issued a flood warning for the Napa River in St. Helena and the Napa area, with peak river levels expected on Sunday afternoon.
The warning was first issued shortly after 10:30 p.m. Friday for the St. Helena stretch of the Napa River, with the Napa area added at 5 a.m. Saturday. The warning remains in effect until 8 p.m. Sunday.
A wind advisory was issued until 10 a.m. Sunday, with wind gusts reaching 30 miles per hour at lower elevations and up to 50 miles per hour at higher elevations.
Barry Martin, a spokesman for the city of Napa, said Saturday afternoon the city’s projections indicate the flood control improvements that have been completed “should accommodate the expected water flows, and that the Napa River will remain mostly within its banks in areas south of Lincoln Avenue.”
Martin continued, “If rainfall totals reach the maximum predicted, there may be minor flooding near the Lincoln Avenue Bridge, and, as designed in the flood project, the lower portion of Veterans Memorial Park may be inundated. As a precaution for public safety, Veterans Memorial Park and the Riverfront promenade, as well as the Oxbow Preserve park, will be closed to the public throughout (the) day Sunday.”
Three to 4 inches of rain was expected at lower elevations and up to 8 inches of rain at the higher elevations, according to the city. The heaviest rainfall is expected between 6 a.m. and noon Sunday.
The forecast calls for the river in the Napa area to peak at near 27 feet Sunday afternoon, according to the National Weather Service. Flood stage is 25 feet.
In St. Helena, the river is expected to exceed the flood stage of 16 feet at noon Sunday, then crest at 18 feet before falling in the evening. The Napa River was measured at 4.6 feet at 1:30 p.m. Saturday, according to the National Weather Service.
The city of Napa has set up a self-serve sandbagging operation on Freeway Drive, just north of Napa Premium Outlets, that is open around the clock.
At flood stage, minor flooding is expected in the lowest areas along the river, including some rural roads. But at 18 feet, moderate flooding is expected along the lower areas of towns, primary and secondary roads.
“We are keeping a close eye on the river and will continue to do so throughout the weekend,” said Napa County Emergency Services Manager Kerry Whitney.
RiverPointe Napa Valley, a resort on Lincoln Avenue, was evacuated Saturday afternoon and 37 modular cottages were being moved, according to front office manager Dana Richardson.
CalFire’s Yountville station was ready to respond to flooding in low-lying areas.
Yountville Town Manager Steve Rogers on Saturday said Yountville’s public works and public safety personnel are on high alert. CalFire has a swift water rescue crew on standby in Yountville.
In St. Helena, police Sgt. Chris Hartley said police are keeping a watch on the river, checking the gauge by the Pope Street Bridge. Sandbags are being distributed at the end of Library Lane and at Crane Park, he said. The police department has contacted St. Helena’s neighborhood watch representatives and reached the manager at Vineyard Valley, a mobile home park that has flooded in the past.
“If something happens, we’re prepared,” said Hartley, who nonetheless was hopeful that the recent multimillion-dollar flood control improvements completed on the Napa River will prevent flooding problems.
On Saturday, as a precaution, county-owned vehicles were moved from the county’s yard on Water Street in Napa, Whitney said. And across Soscol Avenue, parents and students at St. John the Baptist Catholic School on Napa Street placed dozens of sandbags by the school’s and church’s entryways.
According to the weather service, a hazardous-weather outlook covers the Bay Area through the weekend, and a flash flood watch is in effect until early Monday.
As of 5 p.m. Saturday, the storms since Thursday had brought 2.5 inches of rain to the city of Napa’s corporation yard on Jackson Street, according to county gauges.
Mount Veeder recorded 7.7 inches, Mount St. Helena 6.9 inches. Hopper Creek next to Highway 29 received 7.8 inches, and Yountville Cross Road 6.6 inches. -
