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Bedform generation beneath shoaling nonlinear internal waves on a mild slope
Subaqueous sand waves have been observed where nonlinear internal waves (NLIWs) shoal on continental margins. To investigate their generation mechanisms, we propagated periodic NLIWs of depression to shoal upon a sloping bed in a laboratory flume. Following fission of the incident waves, ripple-type...
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Published in: | Geomorphology (Amsterdam, Netherlands) Netherlands), 2024-12, Vol.466, p.109439, Article 109439 |
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Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites |
Online Access: | Get full text |
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Summary: | Subaqueous sand waves have been observed where nonlinear internal waves (NLIWs) shoal on continental margins. To investigate their generation mechanisms, we propagated periodic NLIWs of depression to shoal upon a sloping bed in a laboratory flume. Following fission of the incident waves, ripple-type bedforms were observed between the point of incipient suspension and interaction point (where the quiescent pycnocline intersects the sediment bed). The largest ripples were centered on the bolus birth point, where the NLIWs of elevation, generated by fission, transform into boluses and maximum near-bed velocities occurred. The ripple height and wavelength were consistent with fluvial scaling. In two experiments, where bedload transport was not predicted, the observations showed resuspension to influence ripple generation. Net upslope sediment movement was observed beyond the turning point.
•Ripple bedforms were generated beneath shoaling nonlinear waves of depression in the laboratory•Ripples formed between the point of incipient suspension and the pycnocline-bed intersection•The largest ripples were at the bolus birth point, where waves of elevation transformed to boluses•The ripple height and wavelength were consistent with fluvial scaling |
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ISSN: | 0169-555X |
DOI: | 10.1016/j.geomorph.2024.109439 |