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Date Permissions Signed


Date of Award

Summer 2020

Document Type

Masters Thesis

Department or Program Affiliation

Environmental Studies

Degree Name

Master of Arts (MA)


Environmental Studies

First Advisor

Bach, Andrew J.

Second Advisor

Grossman, Eric E.

Third Advisor

Miller, Ian M.


Coastal development, and the shoreline defenses that accompany it, makes it important to understand the shoreline’s response to anthropogenic modifications. Armoring, or shoreline erosion control structures such as seawalls or riprap, is found on an estimated one third of Salish Sea shorelines and has been shown to degrade nearshore habitat. We compared physical beach characteristics from adjacent sections of armored and unarmored shoreline at locations throughout the Salish Sea to assess the effects of armoring on beach morphology. Nineteen sites, each approximately 500 meters alongshore, were selected from ten reaches sampled with boat-based LiDAR by the WA Dept. of Ecology Coastal Monitoring Program. Cross-shore profiles were generated at 10-meter intervals alongshore in each site. Estimates of beach slope, width, and bluff or armor toe elevation were extracted from digital elevation models along each profile in the foreshore and backshore zones. Parameters were tested for differences between the armored and unarmored sections both regionally and within each site. Locally, direct impacts from armor covering the backshore habitat were more prominent than parameters that may primarily be controlled by geomorphic processes. For example, backshore width and toe elevation were significantly different between armored and unarmored sections and correlated with each other, but parameters such as slope or foreshore width that were not in direct contact with armoring did not show strong differences between sections. These results can be applied to restoration efforts by prioritizing armor removal projects where armor toe is lowest on the beach in order to maximize potential habitat benefits.




shoreline armoring, Salish Sea, beach, coastal, armor, beach morphology


Western Washington University

OCLC Number


Subject – LCSH

Shorelines--Monitoring--Salish Sea (B.C. and Wash.); Geomorphology--Salish Sea (B.C. and Wash.)--Measurement; Beach erosion--Monitoring--Salish Sea (B.C. and Wash.); Bulkheads--Environmental aspects--Salish Sea (B.C. and Wash.)

Geographic Coverage

Salish Sea (B.C. and Wash.)




masters thesis




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