LOS ANGELES -- The U.S. Army Corps of Engineers Los Angeles District is working overtime to ensure communities devastated by recent wildfires are informed on potential debris flows this storm season.
USACE’s LA District is partnering with Los Angeles County and the California Department of Water Resources to assess and mitigate flood risks in areas affected by wildfires – particularly in the recent Pacific Palisades and Eaton fires – under USACE’s Public Law 84-99 authority.
“We have long-standing and close relationships with the California Department of Water Resources and Los Angeles County that allow us to quickly develop flood-risk mitigation solutions,” said Col. Andrew Baker, USACE LA District commander. “This is a great example of federal and state agencies working together to provide solutions, not only for the Corps’ ongoing wildfire debris removal efforts, but also for the communities at large.”
Wildfires can significantly alter hydrologic processes, increasing the risk of flash floods, debris flows and water supply issues, said Tim Fairbank, chief of USACE LA District’s Hydrology and Hydraulics Section.
USACE leverages expertise and resources from multiple agencies, he said, with the purpose of developing state-of-the-art hydrologic and hydraulic models to predict post-fire flood risks.
USACE’s LA District, in collaboration with its county and state partners, worked quickly to develop data and modeling to predict potential debris flows and flooding at an Environmental Protection Agency transfer site near Topanga Canyon in Malibu.
Early results for the site indicated there is a potential for a debris flow in the canyon; however, there is a negligible probability the site will be inundated by either a clear water or debris flow event during the forecasted storm this week.
The multi-agency team also is working on similar models for the entire Eaton and Pacific Palisades burn scars; however, results will not be ready for the Feb. 12-14 storm event.
“Once USACE and the Department of Water Resources teams complete their data generation and modeling, we will have a much better understanding of where debris flows might occur and how much debris will be carried in the debris flows,” Fairbank said. “This modeling will give residents and emergency responders critical information to inform them on where and the volume of potential debris flows, so they can move to safety prior to the actual event.”
The LA District leveraged subject matter experts from across the entire U.S. Army Corps of Engineers, including from its laboratories, to conduct this analysis.
In addition to modeling predictions for debris flows, hydraulic and geotechnical engineers with USACE’s LA District Engineering Division physically assessed the EPA’s transfer site near Topanga Canyon Feb. 7 and Feb. 10 to advise EPA on measures to reduce potential risks at the site from impending and future storms.
USACE engineers plan to be back at the site Feb. 13 to observe effects of the rain event and to better predict the effects of future rain events in the area.
PUBLIC LAW 84-99
Under Public Law 84-99 – Emergency Response to Natural Disasters – USACE has the authority to provide for emergency activities in support of state and local governments prior to, during and after a flood event and can provide both emergency technical and direct assistance in response to flooding and coastal storms.