Storm surges and coastal inundation during extreme events in the Mediterranean Sea: the IANOS Medicane

The IANOS Medicane was one of the most severe storms that have formed in the Mediterranean Sea with Category 2 Hurricane characteristics. The storm induced a significant increase in sea-level elevation along its pathway and caused storm surges at the central Ionian Sea with consequent impacts on coastal regions of the Ionian Islands and western Greece. An integrated approach, based on hydrodynamic ocean simulations, coupled to meteorological and coastal flooding simulations, is used in combination with field and satellite observations to analyze the marine weather conditions, the storm surge characteristics, and the coastal inundation characteristics due to the impact of IANOS Medicane in September 2020. The evolution of the Medicane and the respective storm surge in the ocean have been successfully recorded by the met-ocean simulations, part of an active public-access operational forecast system. Both wind and atmospheric pressure patterns affected the storm surge variability over the Ionian Sea. The direct intrusion of the Medicane from the central Mediterranean Sea toward the Ionian Sea formed storm surges over several coastal areas, even before the storm’s landfall, due to the accompanying onshore currents. Storm surges in the order of 30 cm generated extensive flooding over lowland coastal areas, as confirmed by both satellite (Normalized Difference Water Index, NDWI) and numerical (coastal inundation modeling) data. Satellite-derived and simulated estimations showed that, in specific coastal regions, the run-up of seawater extended up to 200 m inland, depending on the hydraulic connectivity between the lowland areas, which determined the inundation extents during the storm surge.