Rip current observations on a low-sloping dissipative beach

Shari L. Gallop, Karin R. Bryan, Sebastian Pitman, Ranasinghe W M R J B Ranasinghe, Dean Sandwell

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

    3 Citations (Scopus)

    Abstract

    Rip currents are the main cause of beach rescues and fatalities. Key drivers of rip current hazard are: (1) fast current speeds; and (2) the exit rate of floating material from inside to outside of the surf zone. Exit rates may vary temporally, such as due to Very Low Frequency (VLF) motions, which have a period on the order of 10 minutes. However, there is little field data to determine the driver(s) of exit rate. Therefore, the aim of this research was to determine rip current circulation patterns, and specifically, determine their relationship to surf zone exits, on a high-energy dissipative beach. Three days of field measurements were undertaken at Ngarunui Beach, New Zealand. Three daily surf zone flow patterns were found: (1) alongshore; (2) surf zone eddy with high exit rate; and (3) surf zone eddy with no exits. There were strong infragravity peaks in energy within the surf zone, at 30-45s, although none at VLF (∼10 minute) frequencies. Further research is underway to determine what drove the high surf zone exit rate observed at Ngarunui Beach.

    Original languageEnglish
    Title of host publicationAustralian Coasts and Ports 2015 Conference
    PublisherAustralian Coasts and Ports
    Pages304-307
    Number of pages4
    Publication statusPublished - 2015
    EventCoasts and Ports 2015 Conference - Pullman hotrel, Auckland, New Zealand
    Duration: 15 Sep 201518 Sep 2015
    http://www.coastsandports2015.com/

    Conference

    ConferenceCoasts and Ports 2015 Conference
    CountryNew Zealand
    CityAuckland
    Period15/09/1518/09/15
    Internet address

    Fingerprint

    Beaches
    Mine rescue
    Flow patterns
    Hazards

    Keywords

    • Dissipative beach
    • Infragravity waves
    • Rip currents
    • Surf zone
    • Video imagery

    Cite this

    Gallop, S. L., Bryan, K. R., Pitman, S., Ranasinghe, R. W. M. R. J. B., & Sandwell, D. (2015). Rip current observations on a low-sloping dissipative beach. In Australian Coasts and Ports 2015 Conference (pp. 304-307). Australian Coasts and Ports.
    Gallop, Shari L. ; Bryan, Karin R. ; Pitman, Sebastian ; Ranasinghe, Ranasinghe W M R J B ; Sandwell, Dean. / Rip current observations on a low-sloping dissipative beach. Australian Coasts and Ports 2015 Conference. Australian Coasts and Ports, 2015. pp. 304-307
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    abstract = "Rip currents are the main cause of beach rescues and fatalities. Key drivers of rip current hazard are: (1) fast current speeds; and (2) the exit rate of floating material from inside to outside of the surf zone. Exit rates may vary temporally, such as due to Very Low Frequency (VLF) motions, which have a period on the order of 10 minutes. However, there is little field data to determine the driver(s) of exit rate. Therefore, the aim of this research was to determine rip current circulation patterns, and specifically, determine their relationship to surf zone exits, on a high-energy dissipative beach. Three days of field measurements were undertaken at Ngarunui Beach, New Zealand. Three daily surf zone flow patterns were found: (1) alongshore; (2) surf zone eddy with high exit rate; and (3) surf zone eddy with no exits. There were strong infragravity peaks in energy within the surf zone, at 30-45s, although none at VLF (∼10 minute) frequencies. Further research is underway to determine what drove the high surf zone exit rate observed at Ngarunui Beach.",
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    Gallop, SL, Bryan, KR, Pitman, S, Ranasinghe, RWMRJB & Sandwell, D 2015, Rip current observations on a low-sloping dissipative beach. in Australian Coasts and Ports 2015 Conference. Australian Coasts and Ports, pp. 304-307, Coasts and Ports 2015 Conference, Auckland, New Zealand, 15/09/15.

    Rip current observations on a low-sloping dissipative beach. / Gallop, Shari L.; Bryan, Karin R.; Pitman, Sebastian; Ranasinghe, Ranasinghe W M R J B; Sandwell, Dean.

    Australian Coasts and Ports 2015 Conference. Australian Coasts and Ports, 2015. p. 304-307.

    Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

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    AU - Sandwell, Dean

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    AB - Rip currents are the main cause of beach rescues and fatalities. Key drivers of rip current hazard are: (1) fast current speeds; and (2) the exit rate of floating material from inside to outside of the surf zone. Exit rates may vary temporally, such as due to Very Low Frequency (VLF) motions, which have a period on the order of 10 minutes. However, there is little field data to determine the driver(s) of exit rate. Therefore, the aim of this research was to determine rip current circulation patterns, and specifically, determine their relationship to surf zone exits, on a high-energy dissipative beach. Three days of field measurements were undertaken at Ngarunui Beach, New Zealand. Three daily surf zone flow patterns were found: (1) alongshore; (2) surf zone eddy with high exit rate; and (3) surf zone eddy with no exits. There were strong infragravity peaks in energy within the surf zone, at 30-45s, although none at VLF (∼10 minute) frequencies. Further research is underway to determine what drove the high surf zone exit rate observed at Ngarunui Beach.

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    Gallop SL, Bryan KR, Pitman S, Ranasinghe RWMRJB, Sandwell D. Rip current observations on a low-sloping dissipative beach. In Australian Coasts and Ports 2015 Conference. Australian Coasts and Ports. 2015. p. 304-307