If the highest waves ever measured were in the North Atlantic during a winter storm (20 m, see Phenomenal seas), and if the Southern Ocean storms are proverbial, the Mediterranean Sea is not without its rages, while having densely inhabited coasts. Assessing coastal impacts of storms is thus of foremost importance in the region – especially when they can be combined with flash floods, and the wrong wind direction (as shown in Flash flood at the Têt river mouth ).

The storm Gloria hit the North-West basin of the Mediterranean Sea in January 2020. It was one of the most intense such event during the last decade, with unusual aspects. It caused severe damages on the Mediterranean coasts of Spain, and part of France’s ones, too. Altimetry does not enable to monitor such an event hourly close to the coasts. However, the data the different satellites provides can be assimilated into wave models in advance to forecast, or after the event to better understand and assess the damages. Validating the results of a model without assimilation is also interesting, since the validation data and the model are quite independent then.

In the Ebro Delta, the storm surge is modelized over 40 cm, in a region which is low-lying and was thus flooded, while in Balearic Islands there was no storm surge impact. However, the Eastern coast of Mallorca was hit by high waves topping over the high cliffs (over 15 mthat caused significant damage to coastal assets. Such information, and also a look into historical records can help in planning to mitigate such extreme events.
With Swot, altimetry will get closer to the coasts at high resolution, thus improving the altimetry data resolution in such areas, and also in the open ocean. Modelling will assimilate those to provide with forecasts and impact maps.