Les plages sableuses en environnement macro-tidal : de l'influence de la pente sur les processus morphodynamiques

Abstract : This PhD work is focused on the morphodynamic of a pocket beach, located in a macrotidal environment. The beach type is intermediate, with a low tide terrace. The study is based on in situ observations, collected during field campaigns organized during the PhD. The objective is to characterize the beach slope impact on hydrodynamics processes and beach morphology. The water levels dynamic, infragravity waves propagation and turbulence generation in the swash zone, are examined and linked to the beach slope variability.The empirical formulations proposed in the literature show large under-estimations of water levels in the site. Empirical formulations adapted to the beach are proposed.The characteristic break slope presents along the cross-shore profile of low tide terrace beaches is studied. The variability of the break slope location is relevant to explain the short term accommodation of the beach. Under incident wave energy, the location of the beach slope moves shoreward, allowing higher wave dissipation by the low tide terrace. Nevertheless, the reflective part is reduced, which leads to a vulnerable state of the upper beach under strong forcing associated with high tide. The location of the beach slope is found to be a good indicator of the beach vulnerability under a given wave forcing. It provides valuable information in the globalized beach erosion context.
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Charles Caulet. Les plages sableuses en environnement macro-tidal : de l'influence de la pente sur les processus morphodynamiques. Sciences de la Terre. Université de Bretagne occidentale - Brest, 2018. Français. ⟨NNT : 2018BRES0079⟩. ⟨tel-02139367⟩

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