COMPARISON OF SPECTRAL REFRACTION AND REFRACTION-DIFFRACTION WAVE MODELS

Wave energy estimated from linear, spectral wave propagation models incorporating refraction and refraction-diffraction are compared over two bottom configurations: an analytic circular shoal and relatively smooth coastal bathymetry from San Diego, California. The agreement between the two models improves with an increase in the width of the incident directional spectrum and with a decrease in the complexity of the local bathymetry. There are, however, significant differences between the model transformations of directionally narrow spectra on both bathymetries. Pure refraction models are not quantitatively accurate in these cases. These comparisons also demonstrate the importance of directional wave spreading in transformations over even relatively simple natural bathymetry. Data from a fundamentally low-resolution pitch-and-roll buoy, if used as the sole source of directional information for incident waves, can lead to significant uncertainty in wave heights estimated by the refraction-diffraction model.