HINDCASTING WAVE SPECTRA IN FINITE-DEPTH WATERS

A model is described for hindcasting or forecasting waves in finite-depth waters. The model is particularly applicable to coastal sites where the water is depth-limited. The wave energy density spectrum is modelled in the frequency-directional domain. For each spectral component a ray is defined along which wave energy propagates to reach the site. For sites exposed to the open ocean a background spectral wave model is required to provide input to the ray endpoints. Further growth and dissipation is then effected along the rays according to the local wind and water depth. The model was used to hindcast wave spectra over a period of 9 months for a site in the Canterbury Bight, New Zealand. The results were compared with measurements from a Waverider buoy at the site. The model succeeds in explaining about 40% of the variance in measured significant wave heights. However, the present application is handicapped by errors inherent in the background spectral model and in specifying the local wind.