The Heightened Risk: Wildfires and Post-Burn Debris Flows

The current threat stems directly from the catastrophic wildfires that swept through Los Angeles County earlier this year, consuming over 17,000 structures and tragically claiming more than 30 lives. These fires stripped hillsides of vegetation, leaving the soil vulnerable to erosion and significantly increasing the risk of debris flows during periods of intense rainfall. Without root systems to bind the earth, even moderate precipitation can trigger landslides composed of mud, rocks, and charred debris.

This isn’t a new phenomenon. The vulnerability of burn-scarred landscapes to post-fire debris flows has been tragically demonstrated in recent years. In 2018, the community of Montecito suffered devastating mudslides following a downpour on slopes previously scorched by a massive blaze, resulting in 23 fatalities and widespread property damage. February’s rains also unleashed similar flows in areas affected by the January fires, including Sierra Madre, where debris inundated streets and damaged homes. A Los Angeles Fire Department vehicle was even swept into the ocean by a powerful surge along the Pacific Coast Highway.

The National Weather Service (NWS) has described the approaching storm as “rare and very potent,” forecasting up to 4 inches of rain in some areas. Ariel Cohen, meteorologist in charge of the NWS in Los Angeles, cautioned that the storm’s unpredictability presents a significant challenge. “The nature of this system is such that we cannot be certain about exactly when and where these impacts will strike, the exact details until right before they occur at the earliest,” he explained.

Beyond the immediate threat of debris flows, the storm is expected to bring high winds capable of downing trees and power lines. As of Monday night, over 16,000 customers were already without power, according to PowerOutage.us. Further north, the Sierra Nevada mountains are bracing for up to 3 feet of snowfall.

The impact isn’t limited to Southern California. Heavy rain has already begun to fall across Northern California, causing urban flooding in the San Francisco Bay Area. Businesses, like Gladstones Restaurant along the Pacific Coast Highway, are proactively closing in anticipation of the storm’s arrival, recognizing the area’s history of debris flow.

Do you think current infrastructure is adequately prepared to handle the increasing frequency and intensity of extreme weather events linked to climate change? What further steps should be taken to protect vulnerable communities?

Frequently Asked Questions About Storm Preparedness

• What is a debris flow and why are wildfire-affected areas at risk?

  A debris flow is a rapidly moving mass of mud, rock, and vegetation. Wildfires remove vegetation, leaving soil unstable and prone to erosion during rainfall, increasing the risk of these flows.

• How can I stay informed about evacuation orders and weather updates?

  Sign up for local emergency alerts through your county’s emergency management agency and monitor the National Weather Service website for the latest forecasts and warnings.

• What should I do if I am ordered to evacuate?

  Leave immediately. Bring essential supplies, including medications, important documents, and a change of clothes. Follow designated evacuation routes.

• Is it safe to return to a wildfire-affected area after a storm?

  Only return when authorities have declared it safe. Be aware of potential hazards such as downed power lines, unstable slopes, and lingering debris.

• What resources are available to help with disaster recovery?

  The Federal Emergency Management Agency (FEMA) offers assistance to individuals and communities affected by disasters. Visit FEMA’s website for more information.

• How does climate change contribute to the increased risk of these events?

  Climate change is exacerbating extreme weather events, including wildfires and intense rainfall, creating conditions that increase the likelihood of debris flows and other hazards. Learn more about the link between climate change and heavy precipitation from the EPA.