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Hydro-sedimentary dynamics of coastal zones dominated by tides and waves

Xabier Bertin -CNRS-La Rochelle University, Francia - ofrecerá el 28 de febrero a las 16.15 h en el Auditorio IH Cantabria, una charla sobre "Hydro-sedimentary dynamics of coastal zones dominated by tides and waves".


Estuaries and tidal inlets are good examples of coastal zones dominated by tides and waves.
Environmental, social and economic interests are often very important at these coastal regions and include navigation, aquaculture or the stability of the adjacent shorelines. Moreover, these environments often display low-lying zones, which can occasionally be flooded during storms. In a context of sea-level rise and increase in storminess, it appears essential to understand the physical processes controlling the strong dynamics of these environments, before being able to predict their future development. This presentation illustrates the research that I am developing at the joint research unit LIENSs (UMR 7266 CNRS-La Rochelle University). The first part presents a recent hindcast of the storm surge associated with Xynthia, a mid-latitude storm that severely hit the central part of the Bay of Biscay in February 2010. The implementation of a new storm surge modelling system over the North-East Atlantic Ocean resulted in good predictions of tides, waves and surge during Xynthia. The analysis numerical results showed that the larger-than-normal surge during Xynthia resulted from an Ekman transport, strongly enhanced by the presence of young and steep waves. The development oscillations after the storm peak was explained by a new phenomenon of resonance of the surge wave over the continental shelf. The second part of this talk will discuss the morphodynamics of wave-dominated inlets, based on several studies performed on the west coast of Portugal (figure 1). Once the observed morphological changes are reasonably reproduced by our modelling system, numerical results and field data are analyzed in order to explain the enlargement of the inlets during fair weather conditions and their shoaling and closure during winter storms. The former behavior is explained by strongly distorted tides while the latter is explained by the combination of several wave-induced processes:

  1. the so-called “bulldozer effect” due to the shore normal component of wave-induced forces;
  2. the presence of lateral barotropic pressure gradients, accelerating longshore flows towards the inlet;
  3. the convergence of longshore transport due to wave refraction over the ebb-shoal and
  4. wave blocking during the ebb. Recently acquired field data also suggest that infragravity waves may play a major role.

Descripción del evento

Fecha de inicio: Jueves, 28 Febrero-2013 - 16:15
Capacidad: 100
Plazas disponibles: 100
Lugar IH Cantabria / Fundación IH
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