Nearshore wave field simulation at the lee of a large island

• Spectral wave model applied on three-grids nesting in North Aegean Sea.
• Wave model coupled with three-dimensional hydrodynamic model.
• Model forcing through offshore wind and wave buoy.
• Model results calibrated against in-situ observations at the sheltered nearshore zone.
• Extreme wind and wave scenario analysis for North Aegean Sea.

The ability of SWAN model to adequately reproduce the complex wave field at the lee of a large island (Thassos Island, North Aegean Sea) is examined herein. SWAN model was forced by the POSEIDON wind and wave offshore buoy and applied on three-nested grids under stationary mode, in direct coupling to a three-dimensional hydrodynamic model. SWAN model results were validated against in-situ observations at the sheltered nearshore zone, exhibiting fair underestimations in the computation of wave parameters, especially for waves entering the low-resolution computational grid. Cross-correlation analysis on the concurrent dataset revealed that northward propagating waves reach the nearshore zone in 4–5 h, while a time-lag of nearly 12 h was shown for the southward propagating waves. SWAN results at the nearshore field indicated a significant wave energy reduction at the sheltered region (~47%), associated with significant wave directional change. The coupling of SWAN to ELCOM improved model's performance on computing the wave propagation direction. The validated model was run under extreme wind and wave conditions illustrating that Athos Peninsula diffracts the southern waves, reducing their energy as they propagate around Thassos Island, thus inducing an asymmetry in favor of south-eastern waves.

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