Although the recent wildfires in Southern California are now
considered contained, they have sparked a new fear of increased
flooding and landslides.
“Any area where the fire occurred will have potential
problems for runoff during the upcoming rainfall,” said Mark
Savage, captain of the Los Angeles County fire department.
Meghan Fay, a first-year music history student who lives in
Arrowhead, said her house was spared from the fires. Although she
is used to landslides and flooding in her area, Fay said the
concern this time is greater, especially because it would add an
increased financial burden to an already strained situation for
most families in the community.
Charred areas, particularly in San Bernardino County, where
every watershed along the foothills was lost, face an increased
threat of dangerous landslides this winter. The rainfall season
could begin as early as this weekend, said Van Olson, deputy
director of the San Bernardino Office of Public Works.
“It’s an extreme concern for us. … It’s a
real alarm going off,” she said.
Areas in San Bernardino County threatened by landslides and
flooding include Hesperia and Cajon Pass, Summit Valley and the
foothills.
San Bernardino county officials are concentrating on possible
preemptive measures, including sandbagging and using K-rails and
water and debris diversion structures, Olson said.
Antony Orme, a UCLA geography professor who deals with post-fire
erosion, said the landslide danger lies in the lack of vegetation
cover and decreased root strength caused by the fires.
This could lead to potential erosion and mass movements of the
land, Orme said.
Increased debris flow is also a potential problem that follows
fire destruction. Debris could flow into streams and channels
leading to the lowlands and the coast.
Charred areas in the Los Angeles County facing a landslide
threat include Claremont, Palmer Canyon, residential areas near
Sycamore Canyon Park, Simi Valley, the Stevenson Ranch area and the
Val Verde unincorporated area.
The Los Angeles County Fire Department and the County Office of
Public Works are evaluating fire damage and sediment quantity in
watersheds. Preemptive measures, such as seeding and water
diversion methods, could be implemented.
“We will try and implement measures in the field to
protect the county and residents,” said Marina Janofsky, a
spokeswoman for the Los Angeles County Office of Public Works.
“Flood control won’t be compromised,” she
said.
Los Angeles County water reservoirs, which are meant for flood
control and water conservation, will be monitored through the storm
season to determine if sediment removal and cleanup will be
necessary, said Janofsky.
Whether hazardous landslides do occur as a result of the recent
wildfires depends on the intensity of future rainfall. High
intensity rainfall will result in the movement of the burned
hillsides.
Less intense rainfall, however, can help prevent debris flows
and landslides by generating weed growth and the germination of
seeds exposed by the fire.
“In this instance, we had a few days of enough rain to
help trigger vegetal response, which could be a good thing as long
as heavy rains hold off for a while,” Orme said.
Fire damaged areas in San Diego, said Olson, also face similar
landslide and flooding problems due to fire destruction.
Olson added that elevated forest communities in the San
Bernardino County still face a fire threat.