Open-File Report 2011–1150
1U.S. Geological Survey, MS 966, Denver Federal Center, Denver, Colo. 80225
2University of Puerto Rico, Mayagüez, Puerto Rico
This 1:12,000-scale map shows an inventory of debris flows caused by rainfall during 1996 in a 94.4 km2 area in the southern Coast Range of Oregon. This map and associated digital data are part of a larger U.S. Geological Survey study of debris flows in the southern Coast Range. Available evidence indicates that the flows were triggered by a rain storm that occurred between November 17 and 19. The closest rain gage in the Coast Range (Goodwin Peak) recorded 245 mm during the storm. Maximum rainfall intensity during the storm was 13.2 mm/hr on November 18. Debris flows were photogrammetrically mapped from 1:12,000-scale aerial photographs flown in May, 1997. The inventory is presented on imagery derived from LiDAR data acquired in 2008. We classified mapped debris flows into four categories based on the type of debris-flow activity: (1) discrete slide source areas, (2) predominantly erosion, (3) predominantly transport or mixed erosion and deposition, and (4) predominantly deposition. Locations of woody-debris jams are also shown on the map. The area encompassed by debris flows is 2.1 percent of the 94.4 km2 map area.
First posted August 10, 2011
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Coe, J.A., Michael, J.A., and Burgos, M.M., 2011, Map of debris flows caused by rainfall during 1996 in parts of the Reedsport and Deer Head Point quadrangles, Douglas County, southern Coast Range, Oregon: U.S. Geological Survey Open File Report 2011–1150, 9 p. pamphlet, 1 sheet, scale 1:12,000.
Rainfall in November, 1996