Burning of heath and wood land is a normal part of the life cycle. It
is preventing the regular occurrence of small fires that leads to
dangerous brush buildup and huge, uncontrolled fires. My bet is that
green shoots will be showing within a couple of weeks, and this time
next year you will have a fine new cover everywhere. As for a lahar -
why would you expect that?
The So. Cal. brush land is a special case. It's bred to burn. It's a
dry land climate brush land, where the foliage ends up creating its own
waxy outer layers to prevent moisture loss. Which just happen to be
especially flammable. And one neat trick is that they add a layer of
waterproofing to the soil, so that after a fire when a big rain comes,
it won't soak in.
Add to that the West Coast weather, where the jet stream acts like a
fence that collects the rain storms off of Hawaii and herds them all to
one spot. You can end up with 5 to 10 inches of rain in a day, (like
Seattle got a week ago Monday). The jet stream flails up and down the
coast like a garden hose with no one holding it.
So, sometimes you end up with house sized boulders bouncing down the
canyons and leaving mud flows several feet deep on the alluvial fans.
But these, of course being So. Cal., are also the areas that are
considered prime real estate. Crunch.
Some places, they've set up structures to deal with this. One is the
Sepulveda Dam Recreation Area in the San Fernando Valley. Imagine a
square mile of Los Angeles just left there to collect mud, which should
give you some of the scale of the problem. (Given the real estate values
around that place).
Mark Zenier
[email protected] Washington State resident
