Morphodynamic modeling of a low-lying barrier subject to hurricane forcing: The role of backbarrier wetlands

Along much of the world's coastline, coastal barriers serve as first line defense against oceanic and meteorological forces. Extreme storms cause large morphological changes on through high sediment transport rates, which may degrade their defensive capabilities. The understanding impacts is therefore important for resiliency, but often challenged by site-specific characteristics, such land cover availability, poorly understood governing physical processes. Caminada Headlands, Louisiana, USA presents unique considerations morphodynamic modeling with regard to its low-lying topography, variable cover, nearshore muddy substrate sand deficiency. This study investigates effects limited supply barrier island morphology under storm conditions using physics-based numerical models. A high-resolution, local-scale transport/morphodynamic model (XBeach) Headlands verified Hurricane Gustav's (2008) impact pre- post-storm LIDAR surveys. When accurate input data are used create models these tools robust in hindcasting provide a wealth information processes, otherwise difficult obtain observationally. simulation results show that short-duration overwash regime dominates change this influenced backbarrier wetland deterioration. response modulated reduced accommodation space limits landward during subsequent inundation regime. An intact marsh reduces washover distances promotes deposition at supratidal elevations. In light findings, simultaneous restoration/creation wetlands conjunction subaerial beach renourishment be an effective form increasing resiliency subject frequent overwashing.