Modélisation morphodynamique des barres d'avant-plage par analyse de stabilité linéaire : application à la plafe du lido de Sète. Modeling sandbar morphodynamics by linear stability analysis : application to the Lido de Sète beach

Abstract : The North-East part of the Lido de Sète beach owns two nearshore sandbars. Field measurements have shown that the outer bar is relatively stable. The behaviour of the inner bar is more complex. In the classic configuration, both bars are straight and parallel to the shoreline. After stormy conditions, the inner bar can be segmented and reoriented so that each segment becomes parallel to the crests of the incident waves. The aim of this paper is to investigate the mechanisms responsible for the evolution of the inner bar. A linear stability analysis has been performed with a model called MORFO60. Simulations have shown that morphodynamical instabilities can develop along the inner bar when stormy waves come from the South or the East. Calculated morphodynamical evolutions are in good agreement with in situ observations.