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Date Permissions Signed

4-10-2013

Date of Award

2013

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Linneman, Scott

Second Advisor

Suczek, Christopher A., 1942-2014

Third Advisor

Grossman, Eric E.

Abstract

This study examines coarse-sediment transport behavior on a mixed sand and gravel (MSG) beach at Cherry Point Aquatic Reserve in Blaine, Washington. Radio Frequency Identifier (RFId) Passive Integrated Transponder (PIT) tags were used to trace large pebbles and cobbles (51 - 129 mm in diameter) between mid-January and early-March, 2012. Transport data were combined with wind, current and water level data recorded by nearby weather stations, as well as wave data collected by an offshore pressure sensor, into a comprehensive data set. Tide, wind and wave parameters were then input into XBeach, a relatively new nearshore numerical model [Roelvink et al. 2009], to investigate the critical relationships between oceanic and atmospheric factors and the behavior of coarse sediment at the Reserve. Measured displacement of pebbles and cobbles recorded longshore transport in both directions, with little cross-shore movement. This bi-directional transport supports observations made by Bauer [1976] and adds a new facet of beach behavior to the currently favored, uni-directional net-drift cell model [Schwartz et al. 1991, Johannessen & Chase 2006]. During moderate energy wave activity, the duration of elevated wind speeds above 4 m/s controls the extent of tracer displacement. During high energy winter storms, fetch distance and significant wave height control displacement. Another important discovery is the immobility of the lower beach compared to the middle and upper beach. Computer modeling of wave forcing, roller energy and bed shear stress identifies a critical water level needed to bring roller waves close enough to break over the beach profile and affect coarse-sediment transport.

Type

Text

Publisher

Western Washington University

OCLC Number

840646021

Digital Format

application/pdf

Geographic Coverage

Cherry Point Aquatic Reserve (Wash.)

Genre/Form

Academic theses

Language

English

Rights

Copying of this thesis in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

Included in

Geology Commons

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