Part I: On the time scales of wave processes. To systematically improve the SWAN model a study on the wave physics in a tidal inlet was carried out. The third-generation SWAN model was used to compute the wave processes in a tidal inlet for storm conditions. The computed wave processes are propagation (shoaling, refraction and frequency shifting), generation (wind input), non-linear wave-wave interactions (quadruplet wave-wave interactions and triad wave-wave interactions), dissipation (white capping, depth induced breaking and bottom friction), and the work done by the currents against the radiation stresses. The results were normalised, which resulted in the time scales of all wave processes. The time scales were of the order 100s – 1,000s, except for the work done by the currents against the radiation stresses, which is of the order of 1,000s – 10,000s. Part II: Depth-induced breaking: A comparison of the performance of three models. Depth-induced breaking is a subject that has been widely studied, resulting in many scalings on the Battjes and Janssen model. The Battjes and Janssen model, the biphase scaling and the Nelson scaling were selected to compare results in terms of significant wave height. The parameter of interest is the model coefficient . The models were tested with the SWAN model on three different test cases; two reef cases and one sloping bottom profile. The wave period appeared to have a strong influence on the prediction of the significant wave height, in particular on the biphase scaling. The best model over the three test cases statistically is the Nelson scaling.