Analysis of geomorphic and hydrologic characteristics of Mount Jefferson debris flow, Oregon, November 6, 2006 / by Steven Sobieszczyk [and three others] ; prepared in cooperation with the City of Salem, Oregon.

Format:

Book

Government document

Author/Creator:

Sobieszczyk, Steven, author.

Contributor:

Geological Survey (U.S.), issuing body.

Salem (Or.), sponsoring body.

Series:

Scientific investigations report ; 2008-5204.

Scientific investigations report ; 2008-5204

Language:

English

Subjects (All):

Debris avalanches--Oregon--Jefferson, Mount.

Debris avalanches.

Floods--Oregon--Jefferson, Mount.

Floods.

Oregon--Mount Jefferson.

Physical Description:

1 online resource (vi, 18 pages) : color illustrations, color maps.

Place of Publication:

Reston, Va. : U.S. Department of the Interior, U.S. Geological Survey, 2008.

Summary:

On November 6, 2006, a rocky debris flow surged off the western slopes of Mount Jefferson into the drainage basins of Milk and Pamelia Creeks in Oregon. This debris flow was not a singular event, but rather a series of surges of both debris and flooding throughout the day. The event began during a severe storm that brought warm temperatures and heavy rainfall to the Pacific Northwest. Precipitation measurements near Mount Jefferson at Marion Forks and Santiam Junction showed that more than 16.1 centimeters of precipitation fell the week leading up to the event, including an additional 20.1 centimeters falling during the 2 days afterward. The flooding associated with the debris flow sent an estimated 15,500 to 21,000 metric tons, or 9,800 to 13,000 cubic meters, of suspended sediment downstream, increasing turbidity in the North Santiam River above Detroit Lake to an estimated 35,000 to 55,000 Formazin Nephelometric Units. The debris flow started small as rock and ice calved off an upper valley snowfield, but added volume as it eroded weakly consolidated deposits from previous debris flows, pyroclastic flows, and glacial moraines. Mud run-up markings on trees indicated that the flood stage of this event reached depths of at least 2.4 meters. Velocity calculations indicate that different surges of debris flow and flooding reached 3.9 meters per second. The debris flow reworked and deposited material ranging in size from sand to coarse boulders over a 0.1 square kilometer area, while flooding and scouring as much as 0.45 square kilometer. Based on cross-sectional transect measurements recreating pre-event topography and other field measurements, the total volume of the deposit ranged from 100,000 to 240,000 cubic meters.

Notes:

Title from title screen (viewed on July 1, 2015).

Includes bibliographical references (pages 17-18).

OCLC:

277512756