Forests, Rainfall, and Landslides

Science Findings, issue one hundred one / march 2008
USDA Forest Service
Pacific Northwest Research Station
http://www.fs.fed.us/pnw

At the website, look for publications,  find Science Findings, and go
to issue 101.

“Debris flows are common events that can shape stream habitat in
mountainous regions around the world, particularly in the rainy
Pacific Northwest.  “A landslide, once in a stream, can create a
debris flow — a slurry of mud, rocks, and organic material that
scours sediment and wood along steep headwaters streams — and then
deposit this downstream in lower-gradient fish-bearing channels,”
explains Burnett. “But not all landslides enter streams and not all
debris flows travel to streams containing fish.”

“Debris flows can be important sources of gravel, boulders, and large
wood, which are fundamental components of habitat complexity for
salmon.”

A sidebar on Land Management Implications listed 3. The first : “New
models that combine landslide initiation and runout probabilities
offer an unprecedented opportunity to inform land-management
decisions about landslide-associated risks to streams. For the first
time, areas that are sources for landslides likely to affect streams
can be differentiated from those that are not.”

“Overall, Burnett thinks that this is an exciting time for
integrating stream ecology into forest management , especially in
headwater streams …. ‘We’re now at a point where we can begin to
synthesize 15 years of research …’.”

http://www.fs.fed.us/pnw

At the website, look for publications,  find Science Findings, and go
to issue 101.
Very helpful photos, graphs, 4 references (Water Resources Research
43 WO3433: Forest Science 53: 220-238 and 53: 239-253; and
Geomorphology 94:84-205)

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