Concerns rise about mudslides in areas burned by Station fire
September 16, 2009 | 12:52 pm
With the biggest fire in Los Angeles County history about 91% contained, concern is shifting to the threat of flash floods and mudslides.
The Station fire has blackened more than 160,000 acres in the San Gabriel Mountains, leaving barren and eroded hillsides towering over Los Angeles. When the winter rains start, there is little vegetation left in the burn areas to prevent water, silt, rocks and branches from coursing down steep canyons and ravines toward thousands of homes.
Although mudslides are a regular occurrence after fires, authorities are worried that this year’s flows could contain larger amounts of debris than usual. The San Gabriel mountains are made up of rock types that easily shatter and crumble.
“A lot of these slopes are already shedding substantial debris down into the channels – fine sediments and rock falls,” said Richard Hadley, spokesman for a team of scientists, engineers and other experts assembled by the U.S. Forest Service to assess the effect of the fire.
Debris flows off of these hills can be “almost like flowing concrete,” he said. “And on these really steep slopes, there can be a lot of power behind it.” The intense heat from the blaze can also cause the soil to effectively seal itself, resulting in even larger and faster flows, he said.
The so-called Burn Area Emergency Response Team is studying satellite imagery and conducting soil tests to determine where the effects of the fire have been most severe. With that information, it will model water flows, in order to identify the communities that are most at risk and recommend measures to protect lives and property. Possible safety measures include putting in temporary barriers to divert the flows, officials said.
The Los Angeles County Department of Public Works oversees an elaborate flood-control system, including 14 major damns, about 500 miles of open channels and 3,000 miles of storm drains that dump water into the Pacific Ocean.
Nine basins have also been carved into the hills in the affected area to trap silt, rocks and vegetation before storm flows reach urban areas, said Mark Pestrella, public works deputy director. “The system works very well every year, year in and year out,” Pestrella said. But he cautioned that some residences, particularly those located at the foot of burned slopes, could still be at risk.
AW
Yup, cant wait till STORMWATCH 2009 way before it rains and every news org hoping to get something on tape rather than have to put the camera on the ground to make the lite rain look like a torrent...and other dramatics such as talk of the 1933 great christmas flood and mighty el-ninos.
phydeux
Gotta love the the modern L.A. Times and there modern-day publishing strategy. Why not make a story out of something so obvious as the fact the winter rains will cause muddy debris flows to come down the hills after a brushfire denuded them in the fall.
AlanK
phydeux wrote:
Gotta love the the modern L.A. Times and there modern-day publishing strategy. Why not make a story out of something so obvious as the fact the winter rains will cause muddy debris flows to come down the hills after a brushfire denuded them in the fall.
"Why not?" is the relevant question. All newspapers have always done stories like this. And there have always been readers for whom this kind of material is news.
phydeux
AlanK wrote:
phydeux wrote:
Gotta love the the modern L.A. Times and there modern-day publishing strategy. Why not make a story out of something so obvious as the fact the winter rains will cause muddy debris flows to come down the hills after a brushfire denuded them in the fall.
"Why not?" is the relevant question. All newspapers have always done stories like this. And there have always been readers for whom this kind of material is news.
I just wish they'd spend a little more time getting some relavent details. Seems like pull the 'stock' story out of the archives year-after-year with the same, generic info; mudflows after storms, there will be lots more this year since there was more area burned, we're doing studies, yadda, yadda, yadda.
