Recently, a group of scientists announced that an atmospheric ‘river’ of tropical moisture could create storms that last weeks, leave behind 10 feet of rain, and cause massive destruction. Total estimated damage could exceed $300 billion.
The last time the region was struck by such heavy storms was in 1861. Those storms, which lasted 45 days, flooded Sacramento was so severely that the capitol had to be moved temporarily to San Francisco.
It was that storm that researchers used in their simulations of what could come.
Their computer models showed that much of the Central Valley could be inundated; Sacramento would be flooded; and Los Angeles, San Diego, San Francisco, and Orange Counties could all be left with heavy property damage.
And the scientists say that California has the potential to see an even more powerful storm.
Even if the storm doesn’t come, this report should serve as a wake-up call to California cities. Earthquakes aren’t the only danger facing our state.
In Sacramento, work has been underway for the past several years on strengthening the levees.
“It’s been coming down from the Office of Emergency Services at the National level,” says Diane Margetts, the spokeswoman for Sacramento County building department. “They’ve been told to build a 200 year [storm] protection.”
When asked about the scientists report, Ms. Margetts commented that it’s called the “Noah’s Ark” storm.
In that case, she said the question becomes, “[if] you can realistically build up for a 300 or 500 year storm. That would be extrodinarily expensive.”
Ms. Margetts did mention that the County has plans in place to deal with the stages of the storm: before, during and after.
“It comes down to asking residents to look at their own flood risk. They need to have a plan, they need to know their plan, and they need to prepare.”
Sacramento County offers a website, www.stormready.org, as a resource to residents to help them prepare.
And while Sacramento faces the risk of floods, areas in Southern California, which are already reeling from last month’s mudslides, would face the dangers of storm water runoff.
Areas such as San Diego County are constantly preparing for the storms like the ones that struck last December.
“Our crews spend all year preparing for the storms,” said Michael Drake, the public affairs officer for San Diego County Public Works. When a storm hits, they’ll implement their storm patrols.
“Our crews work 12 hour shifts to provide 24 hour coverage,” Drake said.
According to Drake, last December, an intense storm struck before Christmas that left low-level water crossings underwater. There were a lot of trees on the roads and boulders came tumbling down. Crews reacted quickly and were able to recover.
But when it comes to a 500 year storm in the area, Drake said he could only speculate about the effects.
But when a winter storm could put the Santa Margarita Bridge entirely underwater, its effects could be substantial.
Los Angeles’ storm water drainage system is designed to remove up to 183,000 cubic feet of water per second. This water flow is equivalent to 40 million garden hoses turned on to full pressure.
The water that doesn’t make it into these systems is absorbed by the ground, which can soften the soil and lead to large-scale mudslides.
Laguna Beach suffered from heavy flooding and landslides in December after four days of rain dropped just over 6 inches of rain.
The storm scientists predicted would be twenty times as powerful.
The frequency of these storms, according to the scientists, is likely to increase as La Nina conditions occur more often as a result of climate change.
The scientists were careful to note, however, that while these storms are plausible, they would be extreme examples. They were hoping to raise awareness about the need to prepare for all varieties of catastrophes, not just earthquakes.