Breaching of a barrier beach under extreme events: the role of morphodynamic simulations

Abstract

A study of three breaching episodes of the Trabucador barrier beach (Spanish Mediterranean coast) is presented. The analysis is done from a modeling perspective using XBEACH and SWAN. The morphodynamic model (XBEACH) has been validated with the available information. The so obtained Brier Skill Score index has been 0.44 which can be considered as acceptable. Results indicate that in all cases breaching was taking place after 8 hours of wave action (storm) or less. Besides, four main parameters control the final morphodynamic response of the barrier: the storm intensity, the water level and the initial emerged topography and the storm duration. Major breaching occurs when swell waves are in coincidence with high water levels whereas if they are uncoupled the barrier tends to be breached by a diversity of smaller channels.