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Barrier islands in tropical regions are prone to coastal flooding and erosion during hurricane events. The Yucatan coast, characterized by karstic geology and the presence of barrier islands, was impacted by Hurricanes Gamma and Delta in October 2020. Inner shelf, coastal, and inland observations were acquired simultaneously near a coastal community (Sisal, Yucatan) located within 150 km of the hurricanes’ tracks. In the study area, Gamma moved at a slow speed and induced heavy rain, mixing in the shelf sea, and northern winds exceeding 20 m s-1 . Similar wind and wave conditions were observed at this location during the passage of Hurricane Delta. However, a higher storm surge (0.5 m) was measured due to wind setup and the drop (<1000 mbar) in atmospheric pressure. Beach morphology changes, based on GPS measurements conducted before and after the passage of the storms, show alongshore gradients ascribed to the presence of coastal structures and macrophyte wracks on the beach face. Moreover, net onshore sediment transport during the storm contributes to the increase in beach elevation. Urban flooding occurred mainly on the back-barrier associated with heavy rain and the confinement of the coastal aquifer which prevented rapid infiltration. Two different modeling systems, aimed at providing coastal flooding early warning and coastal hazards assessment, presented difficulties in forecasting the coastal hydrodynamic response during these seaward translating events, regardless of the grid resolution and wind forcing employed. Compound flooding plays an important role in this region and hence must be incorporated in future modeling efforts. [ABSTRACT FROM AUTHOR]

The main object of the present work was to study the role of morphodynamic changes in the flooding of a dissipative beach with microtidal regime, considering the simultaneous and individual effects of erosion and flooding in scenarios of long-term mean sea level rise. For this analysis, we selected a sector of the Colombian Caribbean coast with great touristic, historical, economic, cultural and social importance, namely, Cartagena de Indias; specifically, the beach of Bocagrande. By simultaneously considering erosion and flood processes associated with highly energetic waves, the study facilitates the construction of more precise models for assessing threats to coastal zones. SWAN and XBeach nested models were carried out in order to predict morphological changes and flooding during selected cold fronts and hurricanes that affected Cartagena de Indias; those numerical models were calibrated using field campaigns data (pre- and post-storm). The results of this research indicate that flooding on microtidal dissipative beaches under extreme wave conditions should be approached by considering morphodynamics, because ignoring them can underestimate flooding by ~15%. The erosion and flood effects are intensified by sea level rise, resulting in the most unfavorable condition when extreme events are contemporaneous with high tides. [ABSTRACT FROM AUTHOR]

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