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Pulsations in surf zone currents on a high energy mesotidal beach in New Zealand

Pulsations in surf zone currents on a high energy mesotidal beach in New Zealand
Pulsations in surf zone currents on a high energy mesotidal beach in New Zealand
The exchange of material between the surf zone and continental shelf can be driven by pulsations in rip current velocities. However, there is a poor understanding of the relationship of these pulsations to surf zone morphology and material exchange. Moreover, understanding of rip current dynamics has focused mainly on single-barred beaches in an intermediate state, and there have been few studies on high energy beaches. Therefore, this paper undertakes preliminary research on surf zone current velocity pulsations, on a high energy beach in New Zealand. This initial analysis presents results from two days of measurements using Acoustic Doppler Velocimeters and Lagrangian GPS drifters. Drifters revealed pulsations in current velocities on the order of ?0.5–2 m s?1 throughout the surf zone, whether inside a rip current circulation cell or not. More infragravity wave energy was associated with constant pulsations in current velocity, and lower infragravity energy with pulsation bursts, lasting 5–10 minutes, interspersed with periods of relatively constant velocity lasting 15–25 minutes. However, higher wave conditions also reduced the exit rate from the surf zone.
rip channels, surf zone, beach morphodynamics, Raglan, infragravity
0749-0208
378-382
Gallop, Shari L.
c14133fc-9141-47d9-ae9c-84c2513ea8ad
Bryan, Karin R.
85ba8507-148b-46b5-b2bc-c250b663753b
Pitman, Sebastian J.
492b2a91-5c8a-44ae-9d7b-3284a8346cf0
Ranasinghe, Roshanka
595401f8-1450-454d-b9ec-1ea3de9eebb4
Sandwell, Dean
946af9e4-736f-4624-bd96-949f2252a9a4
Gallop, Shari L.
c14133fc-9141-47d9-ae9c-84c2513ea8ad
Bryan, Karin R.
85ba8507-148b-46b5-b2bc-c250b663753b
Pitman, Sebastian J.
492b2a91-5c8a-44ae-9d7b-3284a8346cf0
Ranasinghe, Roshanka
595401f8-1450-454d-b9ec-1ea3de9eebb4
Sandwell, Dean
946af9e4-736f-4624-bd96-949f2252a9a4

Gallop, Shari L., Bryan, Karin R., Pitman, Sebastian J., Ranasinghe, Roshanka and Sandwell, Dean (2016) Pulsations in surf zone currents on a high energy mesotidal beach in New Zealand. [in special issue: Proceedings of the 14th International Coastal Symposium, Sydney, 6-11 March 2016] Journal of Coastal Research, Special Issue (75), 378-382. (doi:10.2112/SI75-076.1).

Record type: Article

Abstract

The exchange of material between the surf zone and continental shelf can be driven by pulsations in rip current velocities. However, there is a poor understanding of the relationship of these pulsations to surf zone morphology and material exchange. Moreover, understanding of rip current dynamics has focused mainly on single-barred beaches in an intermediate state, and there have been few studies on high energy beaches. Therefore, this paper undertakes preliminary research on surf zone current velocity pulsations, on a high energy beach in New Zealand. This initial analysis presents results from two days of measurements using Acoustic Doppler Velocimeters and Lagrangian GPS drifters. Drifters revealed pulsations in current velocities on the order of ?0.5–2 m s?1 throughout the surf zone, whether inside a rip current circulation cell or not. More infragravity wave energy was associated with constant pulsations in current velocity, and lower infragravity energy with pulsation bursts, lasting 5–10 minutes, interspersed with periods of relatively constant velocity lasting 15–25 minutes. However, higher wave conditions also reduced the exit rate from the surf zone.

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More information

Accepted/In Press date: 15 January 2016
Published date: March 2016
Keywords: rip channels, surf zone, beach morphodynamics, Raglan, infragravity
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 402219
URI: http://eprints.soton.ac.uk/id/eprint/402219
ISSN: 0749-0208
PURE UUID: a50fc726-f3aa-4607-a8c9-dd95ebc4b00e

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Date deposited: 02 Nov 2016 10:19
Last modified: 15 Mar 2024 03:11

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Contributors

Author: Shari L. Gallop
Author: Karin R. Bryan
Author: Sebastian J. Pitman
Author: Roshanka Ranasinghe
Author: Dean Sandwell

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