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Communication Dans Un Congrès Année : 2023

3D hydrodynamics of a macro-tidal estuarine environment under wave and tide forcings

Résumé

The sandy estuaries along the English Channel have been silting up for over 10 years. Former geoscientific studies, which assessed sediment stocks, showed that the sedimentary material came from the marine rather than the fluvial part due intense cross-shore dynamics. To understand how the sedimentary material was brought from the coastal sea from estuary, a three-dimensional coupled numerical model was first set up, before simulating hydrosedimentary processes. This study was applied to the bay of the Somme, located in the northern France along the English Channel. This estuarine environment is forced by semi-diurnal tides and ocean waves, that move the predominant fine and coarse sands. The sands moving from coastal ocean, a numerical validation was carried out at coastal, nearshore, and bay sites using several datasets from in-situ field campaigns. Good agreement was found between model and data in the coastal zone regarding to bottom and surface current, sea surface height and mean wave parameters. Vertical profiles of current were also well simulated, especially their modulation by ocean waves. The nearshore simulations reproduced the wave set-up and wave set-down, as well as the cross-shore dynamics with simulated undertow and streaming, and the longshore dynamics showing the longshore current generated by oblique incident ocean waves. Inside the bay, a modulation of the tidal wave is observed, as expected. The water filling and draining of the bay are well represented and follow the tidal phase: the ebb flow drains the bay while the flood flow fills it. These simulations were performed under calm and storm conditions, enabling us to identify the contribution of ocean waves to the hydrodynamics. The next step is to build the hydro-sedimentary model to assess the impact of hydrodynamics on sediment transport and the morphodynamics of the bay.
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Dates et versions

hal-04274720 , version 1 (08-11-2023)

Identifiants

  • HAL Id : hal-04274720 , version 1

Citer

Guillaume Croguennec, Anne-Claire Bennis, Martial Boutet, Gaetano Porcile, Pierre Weill, et al.. 3D hydrodynamics of a macro-tidal estuarine environment under wave and tide forcings. Conférence Internationale d’Océanographie et 19ème Symposium Franco-Japonais d’Océanographie (COAST CAEN 2023), Oct 2023, Caen, France. pp.88. ⟨hal-04274720⟩
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