The effect of island slopes on wave transformation during overwash and inundation

Abstract

Overwash and inundation of barrier islands can lead to vertical accretion of sediment; however, the hydrodynamic processes during these floodings need to be investigated in more detail. The non-hydrostatic wave-flow model SWASH is used to investigate the effect of beach slope steepness on sea-swell and infragravity wave heights and wave shape during inundation. The model-field data comparison shows satisfying results for sea-swell waves, but overestimates infragravity waves and wave asymmetries and skewness, which is most likely caused by the use of the 1-d profile mode. The comparison of different beach slopes suggests that for a steep beach slope less energy is dissipated before the crest compared to gentler slopes, but this is compensated by higher dissipation onshore of the crest. Wave asymmetries suggest that the dissipation of sea-swell waves as well as infragravity waves is primarily caused by wave breaking.