The impact of storms in the morphodynamic evolution of a human-impacted semi-sheltered beach (Agadir Bay, Morocco)

• A multi-method approach yielded concordant results on coastal change.
• Anthropogenic factors accentuate the coastal impact of storms.
• Response of protected versus exposed sectors to storms was identified.
• Dunes play a crucial role in preserving coastal equilibrium during storms.

This study discusses the morphological changes and evolution of Agadir Bay beach (Morocco) in response to eight storms between January 2014 and March 2014. A comparison is carried out of the evolution and variability of the beach in a sector of the bay protected by the commercial harbour of Agadir relative to a sector down drift of the harbour that is more exposed to waves, and changes affecting the beach following these storms are examined. Wave influence is evaluated using numerical simulations. The results show that despite being of relatively low intensity, the two first storm events, and especially storm 1, are responsible for major beach morphological changes. Three zones were identified as a function of the beach sediment dynamics: (i) a northern zone, representing the sector of the beach protected by Agadir harbour, with a net loss of about 21% of the total sediment, (ii) a southern zone, corresponding to the exposed sector with a net loss reaching74% of the total sediment, and (iii) a sector of residual dune that recorded no significant change during the storms.