OBSERVATIONS AND MODELING OF A HYBRID-DUNE LIVING SHORELINE OVERWASH EVENT AT A LONG-PERIOD SWELL DOMINATED BEACH

Sea level rise will significantly increase the need for building and upgrading coastal protection such as coastal dunes and living shorelines. (Morris et al., 2020). Even if emission goals are reached, most coastlines will experience an increase in mean sea levels and energetic wave events and storms (Morris et al., 2020). Coastal protection measures, such as dune restorations and engineered dunes, are crucial in adaptation efforts worldwide (Temmerman et al., 2013; Morris et al., 2022) and hold many advantages over traditional hard engineering structures such as sea walls. However, at sites with more urgent needs for protection and limited space, hybrid structures offer the benefits of both soft (e.g., dunes) and hard structures, for example hybrid dunes consisting of a sand dune containing a solid structure or rock core (Almarshed et al., 2020). In this study, data from five years of hybrid dune living shoreline observations are presented, including performance during a historic 20-year wave event on an intermediate, long-period swell beach. Morphological models are tested on a hybrid-dune erosion and overwash event and compared to high resolution morphological field observations.