VERTICAL CIRCULATION INDUCED BY A SUBMERGED BREAKWATER

A. Sanchez-Archilla, F. Rivero, X. Gironella, D. Verges, M. Tome

Abstract


Submerged breakwaters are structures whose crest height is below the main water level. From a hydrodynamic standpoint this type of structures show significant differences in behaviour with respect to the emerged ones. As an illustration (figure 1), it is well known that the wave height field in the lee of a structure is significantly different for emerged or submerged breakwaters or even the way it varies with the wave height to free-board, H to F, ratio. Also from a hydrodynamic standpoint, the enhanced mass flux over the submerged breakwater may lead to erosion on the lee-side instead of the conventional accretion and r"; ulting tombolo formation. From a morphodynamic standpoint, submerged breakwaters induce lower profile mobilities in addition to helping building a perched beach. In general terms, since a submerged structure exerts a smaller barrier effect, the morphodynamic impact should also be smaller (see for some additional discussion the papers by Van de Graaf and Sanchez-Arcilla and others dealing with the results of the DYNBEACH research project as presented in the Coastal Dynamics 95 and 97 conferences). Finally, this type of submerged structures are normally associated to smaller impacts (e.g. smaller visual impacts, smaller ecological impacts associated to an enhanced water renovation which is essential for a tideless sea as the Mediterranean, etc.).

Keywords


breakwater; submerged breakwater; circulation; vertical circulation

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