A third‐generation wave model for coastal regions: 2. Verification

TLDR

The verification cases span increasing bathymetric complexity and currents, culminating in a tidal gap between barrier islands where waves traverse channels with tidal currents and wind‑generated regeneration. The study verifies the SWAN third‑generation spectral wave model in stationary mode against measurements from five real coastal field cases. The model incorporates shoaling, refraction, wind generation, whitecapping, triad and quadruplet wave‑wave interactions, bottom and depth‑induced breaking, and is evaluated against extensive wave observations including directional data. The results show highly variable wave fields with up to three orders of magnitude energy differences, demonstrate the impact of alternative process formulations, and yield average rms errors of 0.30 m in significant wave height and 0.7 s in mean period—about 10 % of incident values.

Abstract

A third‐generation spectral wave model (Simulating Waves Nearshore (SWAN)) for small‐scale, coastal regions with shallow water, (barrier) islands, tidal flats, local wind, and ambient currents is verified in stationary mode with measurements in five real field cases. These verification cases represent an increasing complexity in two‐dimensional bathymetry and added presence of currents. In the most complex of these cases, the waves propagate through a tidal gap between two barrier islands into a bathymetry of channels and shoals with tidal currents where the waves are regenerated by a local wind. The wave fields were highly variable with up to 3 orders of magnitude difference in energy scale in individual cases. The model accounts for shoaling, refraction, generation by wind, whitecapping, triad and quadruplet wave‐wave interactions, and bottom and depth‐induced wave breaking. The effect of alternative formulations of these processes is shown. In all cases a relatively large number of wave observations is available, including observations of wave directions. The average rms error in the computed significant wave height and mean wave period is 0.30 m and 0.7 s, respectively, which is 10% of the incident values for both.