Small-scale morphology across the surf zone
In: Marine Geology. Elsevier: Amsterdam. ISSN 0025-3227; e-ISSN 1872-6151, meer
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| Author keywords |
small-scale morphology; ripples; morphology; bedforms; nearshore bedforms; surf zone; waves and currents |
| Auteurs | | Top |
- Thornton, E.B.
- Swayne, J.L.
- Dingler, J.R.
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| Abstract |
Small-scale (<5 m horizontal length) nearshore morphologic height variations were measured by combining CRAB surveys with bed elevations acquired with a 1 MHz sonic altimeter mounted on the CRAB during the October Phase of the DUCK94 experiment. Bedform plan views were recorded simultaneously using a 500 kHz side-scan sonar mounted on the CRAB. Waves and currents were measured at the same time. Significant temporal and spatial variations in the small-scale morphology were measured in response to changing waves and currents during the 2 weeks examined. Three cases are examined in detail: (1) mild waves and weak longshore currents resulting in wave ripples throughout the study area; (2) storm waves with strong longshore currents resulting in lunate and straight-crested mega-ripples in the trough of the barred beach; and (3) narrow-band, normally incident waves with a strong rip current resulting in a planar bed except in the throat of the rip where mega-ripples were measured. Wavenumber spectra of the bed were generally broad, indicating newly formed ripples coexisted with residual ripples from the past to form complex, multi-scaled ripple patterns. |
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