Long-term simulations of subaerial beach erosion and overwash during storms

During severe storms, high waves and water levels can reach the subaerial portion of the beach and cause significant morphological change at elevations where the waves cannot reach under typical sea conditions. Coastal dunes may suffer direct wave impact and erode, increasing the likelihood of overwash and breaching, potentially flooding low-lying areas behind the dunes. Barrier islands are also vulnerable to high waves and water levels. The objective of the present study was to develop an analytical model of erosion due to wave impact and sediment transport in the overwash for use in long-term modeling of coastal evolution. Model components describing dune erosion and overwash transport were validated with field data. After validation, the analytical model was employed at two coastal sites, Ocean City on the United States East Coast and the Ebro Delta on the Spanish Mediterranean Coast, to estimate parameters employed for assessing the impact of storms on beaches, such as eroded volume, overwash volume, beach crest reduction, and contour-line recession. These parameters were subsequently analyzed to derive empirical probability distribution functions for risk assessments concerning flooding and erosion in coastal areas.