Assessment of Overwash-induced flooding at two beaches along the Southwest Algarve, Portugal

Kupfer, S.; Ferreira, Oscar; Costas, S.

http://hdl.handle.net/10400.1/16630

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Authors

Kupfer, S.

Ferreira, Oscar

Costas, S.

Abstract(s)

At the Algarve south coast overwash-induced floods are a frequent and destructive phenomenon. In this study return periods for overwash potentials are estimated for two beaches located at the southwest coast of the Algarve (Carvoeiro and Salema) based on runup calculations for the period 1995-2017 after applying two well validated empirical formulations. Results show that overwash potentials are high even for small return periods. Additionally, the suitability of two different indicators (overwash potential and overwash depth) has been tested to represent the flood extent. Results suggest that the flood extent derived from the overwash depth presents several limitations and cannot realistically represent observations, while the flood extent given by the overwash potential (using a simple bathtub approach) fairly represents the overwash-induced flood, even though it can over/underestimate the flood extent for gentle/steep inland slopes. Flood extents derived from the overwash potential, for return periods of 10- and 100-year, show that occupied areas are potentially flooded for both return periods. It is therefore necessary to define appropriate adaptation measures for both beaches, preferably based on detailed risk assessment.