Assessing the impact of extreme storms on barrier beaches along the Atlantic coastline: Application to the southern Rhode Island coast

The predicted median 100-year eroded volume is 46 m3/m for the entire barrier beach, in good agreement with FEMA's empirical value of 50 m3/m at the two “official 1D transects” within the study area; mean post-storm reductions in dune crest elevations are in similar agreement. The model, however, predicts very large alongshore variations of these parameters, with eroded volumes over 1000 m3/m where breaching and the opening of surge channels occurs. Overall, dune segmentation simulated in the model for the 100-year storm appears to be realistic and consistent with dune topography and land cover. XBeach thus provides an improved 2D methodology for assessing the impact of extreme storms on Atlantic barrier beaches, predicting changes in dune morphology, and quantifying the protective role of vegetation, and effects of land cover in general.