Debris flows are churning, water-saturated masses of rock, soil, and organic matter that rush down mountain slopes. They typically originate as landslides and course down stream channels when they reach the valley floor, leaving lobate deposits of debris in their wake. Debris flows commonly include 60 to 70 percent solid particles by volume and attain speeds greater than 10 meters per second (22 miles per hour). As a consequence, debris flows can denude slopes, damage structures, drastically alter streams, and occasionally cause loss of human life. ... Scientific understanding of debris flows has been hampered by their unpredictable timing, location and magnitude, which make systematic observation and measurement of natural events both difficult and dangerous. Consequently, in 1991 the U.S. Geological Survey (USGS), in cooperation with the U.S. Forest Service, constructed a flume to conduct controlled experiments on debris flows. Located about 45 miles east of Eugene, Oregon, in the Cascades Range foothills near the headquarters of the H.J. Andrews Experimental Forest, Blue River Ranger District, Willamette National Forest, this unique facility provides research opportunities available nowhere else. -- Iverson, et.al., 1992 |