Modelling infragravity motions on a rip-channel beach
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Authors
Reniers, A.J.H.M.
MacMahan, J.H.
Thornton, E.B.
Stanton, Timothy P.
Subjects
Infragravity waves
Rip-channels
Edge waves
Numerical modelling
Field measurements
Alongshore variability
Bathymetric coupling
Rip-channels
Edge waves
Numerical modelling
Field measurements
Alongshore variability
Bathymetric coupling
Advisors
Date of Issue
2005
Date
Publisher
Language
Abstract
A non-linear shallow water wave model operating on the time-scale of wave groups is compared with measurements of infragravity motions on
a rip-channel beach to verify the model concepts and assess the model performance. The measurements were obtained during the RIP-current
EXperiment (RIPEX) in concert with the Steep Beach Experiment (SBE) performed at Sand City, Monterey Bay, CA, during the spring of 2001.
The nearshore bathymetry was made up of shore-connected shoals incised by relatively narrow rip-channels spaced approximately 125 m apart.
The comparison considers a 20-day period during which significant changes in both the offshore wave climate and nearshore bathymetry occurred.
The temporal variation in infragravity conditions during the experiment is strong, with computational results typically explaining 70% to 80% of
the observed infragravity motions within the nearshore. In contrast to the temporal variation, the alongshore spatial variation in infragravity
intensity during the experiment is generally weak, even though the underlying bathymetry shows strong depth variations. Model computations
suggest preferential coupling between the computed edge wave motions and the quasi-periodic bathymetry is present, a prerequisite for strong
spatial variability. However, the infragravity field is dominated by cross-shore infragravity motions, which are only weakly coupled to the quasiperiodic
bathymetry, resulting in a weak alongshore variability of the total infragravity motions.
Type
Article
Description
The article of record as published may be located at http://dx.doi.org/10.1016/j.coastaleng.2005.10.010
Series/Report No
Department
Oceanography
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NPS Report Number
Sponsors
The Steep Beach Experiment and EBT and TPS were funded by the Office of Naval Research, Coastal Science Program, under contract N00014-01-WR-20023. JM was funded by the Florida Sea Grant Program. Part of the work presented here was done while AR held a National Research Council-NPS Research Associateship funded through the National Ocean Partnership Program (NOPP) under contract N0001463WR20191 and the Office of Naval Research under contract N00014-01- WR20023. Part of this material is based upon work funded by the National Science Foundation under grant 0136882. Additional funding from the Dutch National Science Foundation, contract DCB.5856 is much appreciated.
Funding
Format
Citation
Coastal Engineering, 2005
Distribution Statement
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.