Wave modeling of a reef-sheltered coastal zone in the Red Sea

Abstract

The coastal areas of the Red Sea are characterized by shallow banks of fringing and barrier reefs that provide protection against coastal hazards and erosion by dissipating wave energy. This study investigates the wave climate and extremes of a reef-protected coastal zone in the Red Sea using a high-resolution coupled wave and circulation model, ADCIRC + SWAN, configured on an unstructured grid forced with the meteorological fields from high-resolution regional atmospheric model. Our simulations suggest that the relatively narrow offshore reefs with steep fore-reef slopes dissipate 40–50% of the wave energy propagating towards the shoreline, and this is more pronounced during extremes. The impact of the coupling on determining the wave climate is negligible, but is significant for storms with ~10 cm higher significant wave height (Hs) during the observed period. The back-reef wave climatology computed from 30-year model simulations shows that the mean Hs distribution is uniform throughout the year, and extremes occur more often from February to May. Different return levels of Hs in the sheltered areas are estimated using extreme value analysis. Our results emphasize that preserving the complex offshore reefs is crucial for mitigating the coastal hazards of high-energy waves which are projected to increase with climate change.