Nearshore and Surf-Zone Morphodynamics: A Global Environmental Model for Predicting Hazards and Changes. Appendix 6. Standing Waves on a Pronounced Bar Trough Beach

摘要

The hypothesis that a pronounced bar-trough surf zone topography favors resonance of standing waves with antinodes located over the bar is examined. Numerical and field investigations of standing waves in a bar-trough surf zone suggest a selective trapping of wave energy at specific resonant frequencies in the subharmonic and the high frequency infragravity bands and a possible suppression of lower frequencies. The resonant frequencies predicted by the numerical model remain fairly constant throughtout the tidal cycle due to the small tidal range typically associated with a bar-trough beach. Cross-shore bar migration changes the resonant frequencies. Numerical simulations show that an onshore bar migration is accompanied by a reduction in the period of the resonant wave and a decrease in the longshore wavelength of the possible edge wave mode.