BARRED-BEACH MORPHOLOGICAL CONTROL ON INFRAGRAVITY MOTION

Rafael Almar, Rodrigo Cienfuegos, Eduardo Gonzalez, Patricio Catalán, Hervé Michallet, Philippe Bonneton, Bruno Castelle, Leandro Suarez

Abstract


A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself.

Keywords


Longwave dynamics; Sandbar; Swash; Nearshore; Laboratory experiment; Non-linear Boussinesq wave modeling; Radon transform; Incoming/Outgoing wave separation; Infragravity resonance

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