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Shoreline erosion on Sauvie Island, Oregon: perceptions and management practices

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Title Shoreline erosion on Sauvie Island, Oregon: perceptions and management practices
Names Long, Season (creator)
Chan, Smauel S. (advisor)
Date Issued 2007-06-18 (iso8601)
Note Master of Science (M.S.)
Abstract Sauvie Island lies at the confluence of the Columbia River and the Willamette River near
Portland, Oregon. Flooding, erosion, and deposition of sediments have been part of the
natural evolution of the island. However, with the construction of multiple dams in the
Columbia River Basin, levees, and hardening of upstream banks, many natural river
processes have been altered, resulting in increased erosion along the Island's shores.
The objectives of this project were to, (i) characterize shoreline erosion as perceived by
waterfront landowners on Sauvie Island, (ii) determine the role of government agencies
in shoreline erosion management, (iii) to "ground truth" property owner and agency
perceptions of recent erosion problems, and (iv) to communicate project findings to all
parties. The research involved surveying shoreline property owners, interviewing relevant
government agency staff to determine their roles and responsibilities for erosion
management, and the use of aerial and orthophotos to verify erosion "hot spots". The
main findings of this study were that: 1) Columbia River residents are the most concerned
about bank erosion, with nearly 25 percent of the respondents losing bank along the
entire length of their property; 2) nearly half of the Columbia River respondents have
installed some form of bank protection along their waterfront, however, only 25 percent
believe that their revetment strategy has prevented further erosion; 3) aerial photo
analysis revealed section of the Columbia River shoreline having (accumulative) erosion
of up to 5 feet per year; 4) current regulatory jurisdiction for erosion monitoring and
control along Sauvie Island is disjointed with no single agency responsible for the
monitoring, permitting, and technical assistance landowner's need when installing
revetment work. An intended outcome of this project is to encourage cooperative
management of shoreline erosion by building understanding of the nature of shoreline
erosion on Sauvie Island and to facilitate communication between landowners and
government agencies regarding extent, management and mitigation.
Genre Research Paper
Identifier http://hdl.handle.net/1957/30162

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