Thursday, August 16 , 2018, 10:03 am | Overcast 71º

 
 
 
 

Local News

A Closer Look at Montecito’s Sweeping New Evacuation Rules

We could have an equally bad event as the Jan. 9 debris flow, scientists say

Eric Nicita, left, and Kevin Cooper, scientists with the federal Burned Area Emergency Response team for the Thomas Fire, measure the depth of the hydrophobic, or water-repellant layer in the scorched soil on the steep mountainside above Montecito. The absence of any vegetation on these slopes heightens the risk of another catastrophic debris flow like the one on Jan. 9. Click to view larger
Eric Nicita, left, and Kevin Cooper, scientists with the federal Burned Area Emergency Response team for the Thomas Fire, measure the depth of the hydrophobic, or water-repellant layer in the scorched soil on the steep mountainside above Montecito. The absence of any vegetation on these slopes heightens the risk of another catastrophic debris flow like the one on Jan. 9. (Los Padres National Forest photo)

On Jan. 7, when Santa Barbara County first issued mandatory and voluntary evacuation orders for Montecito, the National Weather Service was forecasting up to an inch and a half of rain per hour from the approaching storm, the first of the winter.

But the rain that came was much more extreme. Beginning at 3:34 a.m. on Jan. 9, the mountainside that had burned in the Thomas Fire above Montecito was hit with four bursts of intense rain; one of them dumped half an inch in five minutes.

The odds of that occurring were once in 200 years.

By 4 a.m., a massive torrent of mud and boulders was surging through the sleeping community below, overwhelming everything in its path. Twenty-one people died, and two are still missing.

“We knew we were going to have a bad storm,” county Sheriff Bill Brown told a standing-room-only crowd at the Montecito Union School last week. “What we prepared for is not what we received.”

The county Office of Emergency Management last week rolled out a sweeping change in protocol that it said would better protect all communities below burn areas in future storms.

Twenty-four hours before the arrival of any storm that is forecast to bring half an inch of rain or more per hour to those areas, Brown said, he will issue a mandatory evacuation order blanketing all of Montecito and parts of the Carpinteria Valley.

Evacuations on this scale for mountainside communities next to the ocean are unprecedented but necessary, officials said.

“Nobody’s done this before,” said Rob Lewin, county emergency manager. “This is what they do in hurricanes. Let us not be fooled that the mountains have flushed the debris from the Jan. 9 storm. The mountains are loaded.”

The protocol includes a pre-evacuation advisory 72 hours before a storm and a recommended evacuation warning 48 hours before.

In addition to communities below the Thomas Fire, the protocol applies to less populated areas on the Gaviota Coast below the Whittier and Sherpa fire burn areas, and east of Santa Maria below the Alamo Fire.

Half an inch of rain per hour is dangerous in the burn areas because it can trigger landslides and debris flows from loose boulders and soil no longer held in place by dense chaparral, scientists said.

And now that some – but by no means, all – of the debris has been flushed out of the canyons, they say, water may be able to move faster through them.

“It will now take less rainfall to move debris than it did on Jan. 9,” Brown said.

Also problematic, scientists say, is a mountainside microclimate that has the potential to ratchet up rainfall amounts and intensities in the burn areas.

It happens like this: As storms approach the coast from the north, rotating counter-clockwise, they can generate strong winds from the south. These winds drive moisture-laden air off the ocean straight into the steep east-west trending slopes of the South Coast. The moist air cools rapidly as it is lifted upwards, then packs a punch as it drops a load of rain high on the mountainside.

“Because of the extreme topography, the prediction for half an inch of rain per hour can easily result in something twice as much on those slopes above Montecito,” said Kevin Cooper, a biologist with the Los Padres National Forest who served on the federal Burned Area Emergency Response team for the Thomas Fire.

“It’s always worrisome in these situations. We could have an equally bad event as on Jan. 9; it just depends on how hard it rains.”

That’s why the trigger for evacuations is a storm forecast and not the actual amount of rain that comes, Cooper said.

“You can’t wait for something to appear, because it’s like a snow avalanche,” he said. “It looks okay until it’s on top of you.”

County records show that rainfall intensities of half an inch per hour occur at least once on the South Coast almost every year.

The risk of debris flows is greatest in the first year after a fire, but the evacuation protocol will be in place until the vegetation in the burn areas grows back, Lewin told the anxious crowd at Montecito Union School.

“We want you to live your lives and have hope,” he said. “But you have to be prepared to have a bit of a transient life. Make sure you always have a suitcase ready and your gas tank full.”

How long will it take for the vegetation to grow back in the burn area? the audience wanted to know. The unsatisfying answer was: one to five years, depending on the rain.

“Unfortunately, it’s not a simple thing,” Lewin said. 

In an interview, Cooper said he saw very few shoots of vegetation sprouting in the Thomas Fire burn area on a recent visit there. All of the trees are gone, he said, and there’s quite a bit of debris still piled up at the bottom of the creek canyons.

Artificial seeding of burned chaparral slopes has not been effective in the past, Cooper said. It can promote weeds, and if it is done too early, the seeds can be washed away in the rain. The native vegetation comes back just as fast as the seeds, anyway, Cooper said.

“There’s a great seed source still up there, and it’s growing,” he said of the slopes above Montecito. “It’s ready to recover. If we get light rains, it might be hard to walk through these burned areas next spring.”

Melinda Burns is a freelance journalist based in Santa Barbara.

Support Noozhawk Today

You are an important ally in our mission to deliver clear, objective, high-quality professional news reporting for Santa Barbara, Goleta and the rest of Santa Barbara County. Join the Hawks Club today to help keep Noozhawk soaring.

We offer four membership levels: $5 a month, $10 a month, $25 a month or $1 a week. Payments can be made through Stripe below, or click here for information on recurring credit-card payments and a mailing address for checks.

Thank you for your vital support.

Become a Noozhawk Supporter

First name
Last name
Enter your email
Select your membership level
×

Payment Information

You are purchasing:

Payment Method

Pay by Credit Card:

Mastercard, Visa, American Express, Discover
One click only, please!

Pay with Apple Pay or Google Pay:

Noozhawk partners with Stripe to provide secure invoicing and payments processing.

  • Ask
  • Vote
  • Investigate
  • Answer

Noozhawk Asks: What’s Your Question?

Welcome to Noozhawk Asks, a new feature in which you ask the questions, you help decide what Noozhawk investigates, and you work with us to find the answers.

Here’s how it works: You share your questions with us in the nearby box. In some cases, we may work with you to find the answers. In others, we may ask you to vote on your top choices to help us narrow the scope. And we’ll be regularly asking you for your feedback on a specific issue or topic.

We also expect to work together with the reader who asked the winning questions to find the answer together. Noozhawk’s objective is to come at questions from a place of curiosity and openness, and we believe a transparent collaboration is the key to achieve it.

The results of our investigation will be published here in this Noozhawk Asks section. Once or twice a month, we plan to do a review of what was asked and answered.

Thanks for asking!

Click Here to Get Started >

Reader Comments

Noozhawk is no longer accepting reader comments on our articles. Click here for the announcement. Readers are instead invited to submit letters to the editor by emailing them to [email protected]. Please provide your full name and community, as well as contact information for verification purposes only.

Daily Noozhawk

Subscribe to Noozhawk's A.M. Report, our free e-Bulletin sent out every day at 4:15 a.m. with Noozhawk's top stories, hand-picked by the editors.

Sign Up Now >