Spectral wave modeling in fringing reef environments

This study examines the implementation and validity of phase-averaged spectral models in describing wave transformation over fringing reefs. The wave breaking mechanism over the abrupt reef crest, dissipation due to bottom friction, and nonlinear energy transfer over the reef flat set the problem apart from general applications in non-tropical settings. The Simulating Wave Nearshore (SWAN) model, which is widely used in coastal engineering applications, has embedded parameterizations of these surf-zone processes for examination. In addition, we extend the model to include a recently implemented bottom-friction source term for tropical reefs. Comparisons of model predictions with laboratory and field observations over fringing reefs identify promising wave-breaking and bottom-friction parameterizations for calibration. The calibrated parameterizations enable SWAN to reproduce the observed wave height and setup and extend the applicability of spectral models to fringing reef environments. SWAN, however, lacks the parameterization to describe the nonlinear energy transfer toward the infra-gravity band that was observed in the laboratory and field studies.