Evaluating third generation wave spectral models performances in coastal areas. An application to Eastern Liguria

In this work performances of two different wave spectral models (Wavewatch III and SWAN) are presented. Results are compared with those provided by a validated meteocean modelling chain. Potentialities and deficiencies of either the models are evaluated in relation to their numerical accuracy and ability to represent coastal processes. Both of the models are applied to a coastal area belonging to the Northern Tyrrhenian Sea on a finite-elements computational mesh. As expected the two models provide comparable results. Being conceived for nearshore modelling SWAN provides a more detailed representation of coastal phenomena, including for example a parameterization of diffraction which is neglected by WWIII. On the other hand the Operator Splitting Method employed by WWIII to integrate wave action equation provides a better scalability of time step for different phenomena involved in wave modelling, guaranteeing a better computational efficiency for non-stationary modelling.