Coastal flooding on gravel-dominated beaches under global warming

Abstract

This work analyses the effects of sea-level rise on flooding events for 3 different scenarios: present situation (S0), optimistic projection (RCP4.5) and pessimistic projection (RCP8.5). The study area is a gravel-dominated beach in southern Spain (Playa Granada), where the SWAN and XBeach-G models are applied to assess wave propagation patterns, total run-up and flooded dry beach area. The results indicate that sea-level rise modifies wave propagation patterns, with alongshore-averaged increases in breaking wave height equal to 1.2% (1.9%) un-der westerly (easterly) storms in the optimistic scenario and 2.6% (2.4%) in the pessimistic scenario. These increments lead to maximum increases in total run-up greater than 13% (14%) for westerly (easterly) storms in the optimistic scenario and 16% (20%) in the pessimistic scenario. Finally, the increases in flooded dry beach area induced by sea-level rise under westerly (easterly) storms are equal to 1.6% (5.9%) and 1.8% (7.7%) in scenarios RCP4.5 and RCP8.5, respectively, and the maximum increments in flooded cross-shore distances exceed 8% in all cases. The methodology proposed in the present work can be extended to other coasts worldwide for assessing the influence of sea-level rise on coastal flooding events.