Headland structural impacts on surf zone current circulations

Abstract

The paper presents the morphodynamic investigation of embayed beaches through the impact of structural headlands. An XBeach model was successfully applied to predict the surf zone current pattern and to predict morphological features of three different embayment scales for low-moderate-high wave energy events. The formation of central rip currents in embayed beaches is linked to the presence of a sand bar, while topographical headland rips developed adjacent to the headland boundary are caused by the geological control of the headland structure itself. The effect of moderate and high waves has resulted to a decreased number of central rips in a longer embayment thus limiting the beach circulation to the cellular type. This type of rips could provide an initial insight into the offshore transport of sand from the coast. Whether wave breaking occurs outside or inside the embayment determines the initiation of large scale rip currents, megarips. Several factors that lead to the generation of megarip currents in literature should be taken into account as a guideline for morphodynamic studies in a high energy embayed coast. Nevertheless, the characteristics of surf zone current circulation in all cases presented in this study complies with the description of the theoretical embayment scaling parameter (δ') (Short and Masselink, 1999 and Castelle and Coco, 2012). Further establishment of this parameter is needed to properly describe the surf zone current circulation in embayed beach systems.