SoCal Officials Bracing for Potential Damage from Winter of Heavy Rains

Recent satellite images of the Pacific Ocean reveal the power and potential dangers of the El Niño weather pattern. At least four storms were brewing, the farthest still getting going in Asia, and all aimed at California. It’s this pattern—a series of back-to-back-to-back storms seemingly arriving on a conveyor belt—that concerns officials bracing for potential damage from the predicted winter of heavy rains.

“El Niño storms: it’s steady, not spectacular. But it’s relentless,” said Bill Patzert, climatologist at NASA’s Jet Propulsion Laboratory in La Cañada Flintridge. “As this goes on for many weeks, you start to soak the hillsides, then you get more instability. And then you can get serious mudflows—2 to 3 feet in height.”

The Southern California areas at most immediate risk are those recently burned by wildfires—such as the Camarillo Springs community in Ventura County, Silverado Canyon in Orange County, and the Solimar fire burn area north of Ventura, which charred more than 1,200 acres over Christmas weekend. Officials are concerned about flash floods in those areas causing damage to both properties and infrastructure. Vegetation, once burned, can no longer hold back loose sediment, and officials are worried about mud and debris crashing onto Solimar Beach communities, the Pacific Coast Highway and sections of the 101 Freeway all the way up to the Sea Cliff area. Even half an inch of rain in an hour could create a debris flow in these burn areas, said Gil Zavlodaver of the Ventura County Sheriff’s Office of Emergency Services.

But the worst problems will probably come later in the winter. “This is the first major line of storms. The ground isn’t quite saturated yet,” said meteorologist James Thomas of the National Weather Service in San Diego. It’s later in the winter that the risk heightens, particularly in neighborhoods and roads below arroyos and canyons and along the beach.

Besides this El Niño, there are only two similarly strong El Niños over the last half-century. The 1982-83 El Niño caused more than $500 million in property damage in California (more than $1 billion in today’s dollars), unleashed flooding and sent mud and rock raining over canyon and coastal roads, destroying the Seal Beach Pier and severely damaging the Santa Monica Pier. The El Niño of 1997-98 also caused more than $500 million in damage and the unfortunate deaths of 17 people.

Still, although Southern California is at risk for infrastructure damage during this El Niño season, the area is not expected to encounter widespread regional flooding. Such devastating flooding did occur earlier in the 20th century, but civil engineering projects that transformed the Los Angeles, San Gabriel and Santa Ana rivers into concrete-lined flood control channels were successful in creating a regional infrastructure that has protected Southern California from flooding for generations.

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