SANTA BARBRA, Calif. - It will take years for the charred hillside above Loma Alta Dr. in Santa Barbara to recover from last Thursday's Loma Fire.
Two UCSB experts in Earth Surface Processes assessed the site Tuesday.
"The top of the hill's a dangerous spot," said Professor Edward Keller. "If you'd had Eucalyptus trees up here you'd of been toast."
Keller, a well-known local Environmental Geologist, and his PhD student, Paul Alessio, said the nine acres left charred will remain at risk for mudslides for the next five years. When rain comes, the charred soil will respond to the water like glass.
"We call it hydrophobia or water-avoiding or hating," said Keller.
It is a potential risk that the Santa Barbara community knows all too well.
"Here we'd see a lot of fine grain mixed with the water but it could make a slurry that can flood the houses and streets below," said Alessio.
Alessio and Keller calcuated how much mud could come down in the next rain.
"We calculated between two and 10 large dump trucks of sediment could be produced from intense, short duration rain," said Keller. "This assumes 10 cubic yards per truck but will not be equally distributed along the base of slope."
"The amount of dirt that comes off this hillside is really going to depend on the type of rain that you get," said Alessio. "A low intensity and rainstorm will allow the water to soak in."
Keller said events following fires are one of the most hazardous things in California.
"Often they take out just one home."
Both recommend a type of netting system be installed at the base of the hill and, numerous fiber berms placed horizontally along the hillside as the best protection for the homes and street below. Keller said hydroseeding is good, but only in the short term as rain can easily wash away the seeds.
At this point, just days after the fire, Keller said it's too soon to replant the charred hillside.
"Replanting can have problems. You want to let it come back to natural vegetation or you're just creating another potential fire hazard in a year or two."