Short communication: evidence for geologic control of rip channels along Prince Edward Island, Canada

ABSTRACT

Rip currents can move unsuspecting swimmers offshore rapidly and represent a significant risk to beach users worldwide, including along the northern coast of Prince Edward Island (PEI), Canada. Although many rip currents are ephemeral and/or spatially variable in response to changes in the nearshore bar morphology and wave and tidal forcing, it is possible for rip channels to be geologically controlled and quasi-permanent in morphology, location, and flow. Several rip channels along the northern coast of PEI appear in the same location from year to year and correspond to elongated lakes, rivers, or swales behind the modern coastal dune system. Given their persistent location and alignment with back dune hydrology, ground-penetrating radar surveys were collected along Brackley and Cavendish Beaches in July 2019 to determine whether persistent rip channels are associated with now-buried river channels extending beneath the modern dunes and continuing offshore. Strong reflectors similar to V-shaped river valleys are present in alongshore transects at both beaches. These infilled valleys align with back-dune hydrology and persistent rip channels, suggesting modern rip channels are structurally controlled and maintained by antecedent geology. This link provides important guidance to beach access management and the distribution of lifesaving strategies along the affected beaches.

KEYWORDS:

• Rip current
• geologic framework
• prince edward island

Acknowledgments

We would like to thank Prince Edward Island National Park for permitting data collection at the park and for logistical support in the field. We appreciate the insightful and constructive review of this work by USGS reviewers. Funding was provided from the Natural Sciences and Engineering Research Council (NSERC) of Canada. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The research was partially supported by a Discovery Grant to Dr. Chris Houser (University of Windsor) by NSERC.