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IMS-56, Statewide Subbasin-Level Channel Migration Screening for Oregon, by Jed T. Roberts and Lowell H. Anthony

Download complete publication .zip file (29 MB; geodatabase, report, map plate)

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Executive Summary
Channel migration is a geomorphic process by which a stream moves laterally across its floodplain over time. The dynamic forces of erosion and deposition drive the reconfiguration of alluvial channels through scouring of banks and buildup of bars. Channel migration is a known natural hazard in Oregon that poses significant risk to property and infrastructure situated near streams that exhibit certain geomorphic characteristics. However, from a hazard mapping standpoint channel migration has received relatively little attention when compared to other hazards such as landslide, earthquake, tsunami, and flooding. Recent events, like the January 2011 flood and channel migration event on the upper Sandy River (Figure 2-1), have highlighted the need for identification and mapping of channel migration zones, but no statewide screening had been performed to determine areas of varying susceptibility, needed to help prioritize mapping efforts.

In August 2014, the Oregon Department of Geology and Mineral Industries (DOGAMI) was commissioned by the Oregon Department of Land Conservation and Development to perform statewide, subbasin-level screening of channel migration susceptibility for first-order streams. The study objectives included:

A total of 6,913 stream miles were evaluated. Of these, 2,553 miles (37%) were classified as having high channel migration susceptibility, 1,542 miles (22%) as moderate susceptibility, and 2,818 miles (41%) as low susceptibility.

Plate 1 preview image:

Statewide Subbasin-Level Channel Migration Screening for Oregon