̽��ϵ��

Topic

Field observations of structurally-controlled rip currents on the west coast of Vancouver Island

School of Earth and Ocean Sciences

Date & location

• Wednesday, April 15, 2026
• 9:30 A.M.
• Clearihue Building, Room B021

Examining Committee

Supervisory Committee

• Dr. Johannes Gemmrich, School of Earth and Ocean Sciences, ̽��ϵ�� (Co-Supervisor)
• Dr. Jody Klymak, School of Earth and Ocean Sciences, UVic (Co-Supervisor)
• Dr. Stan Dosso, School of Earth and Ocean Sciences, UVic (Member)

External Examiner

• Dr. Rich Pawlowicz, Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia

Chair of Oral Examination

• Dr. Neil Ernst, Department of Computer Science, UVic

Abstract

Rip currents are strong seaward-directed flows generated by the action of breaking waves on beaches. They are considered to be one of the most dangerous coastal hazards due to their ability to quickly transport swimmers and surfers into deeper waters. Since 1936, rip currents have been studied worldwide through a variety of methods including field observations, numerical modelling, and laboratory experiments. One location in Canada where rip currents occur is the Long Beach Unit of Pacific Rim National Park Reserve on the west coast of Vancouver Island. The Long Beach Unit is a popular surfing destination and rip currents at this location have necessitated water rescues and have been responsible for injuries and deaths. In spite of the hazard they pose, rip currents have been under-researched on Canada’s west coast.

Field observations of rip currents were made at two locations in Pacific Rim National Park where rip currents are controlled by the presence of rock features: Long Beach and Wickaninnish Beach. Results from visual, Eulerian, and Lagrangian datasets are combined to examine the influence of the wave field and tide on rip current occurrence, speed, and perceived strength. It is found that significant wave height has the greatest effect on structurally-controlled rip current flow, followed by mean wave period. All three rip current characteristics increase with higher and longer waves, revealing the importance of incident wave energy and increased wave set-up in driving rip current flow. These waves can be represented by two non-standard wave parameters: wave factor Wf and a proxy variable for wave energy flux. Mean wave direction and directional spread show some influence on the rip currents at both locations, in that, during the observation periods, waves favourable for increased rip current speed and strength tended to approach the beaches from certain directions. At Wickaninnish Beach higher waves approached from west-southwest with greater directional spread; while at Long Beach higher and longer waves approached from the south with narrow directional spread. Tidal elevation and motion showed little influence on rip current characteristics at Wickaninnish Beach. Results from this research will contribute to general understanding of structurally-controlled rip currents, and can be used to further improve beach safety in Pacific Rim National Park Reserve.