Abstract: This paper presents an adapted methodology to estimate the different return periods of storm-induced impacts on beaches and foredune systems based on hindcast data, with examples of applications in areas exposed to and sheltered from the wave action. The methodology consists of using wave, tide, and surge reanalysis data to obtain large series of total water level, which are used to estimate the values related to different return periods (5,10, 25, and 50 years). Those levels are summed to the corresponding projection of sea level rise from the worst-case scenario projections. The final values are used to classify the beaches according to the coastal storm impact regime as (1) swash, (2) collision, (3) overwash, and (4) inundation. Finally, the limit between each regime is established based on the relation among dynamical and geomorphological parameters. The methodology was applied to the east (exposed beaches) and north (sheltered beaches) coasts of Santa Catarina Island (Florian´opolis, Southern Brazil), a zone constantly submitted to extreme storm events and where large series of measured data are commonly missing. The results for Santa Catarina Island indicate that the storm impact regime in most of the exposed beaches is similar for different return periods (most of them classified as collision regime). Overwash regime is predominant on sheltered beaches. Sectors with an intense urban occupation are classified as under inundation regime for all return periods, while zones with well-developed foredune are classified as the collision regime. Some of those results could be qualitatively verified with observations from recent storm events, highlighting the value of this kind of methodology to estimate the impact of coastal storms in zones with an important lack of measurements.

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