Comparative Study of Boussinesq Wave Module and Potential Swell Theory in Calculating the Port Agitation: Case of Moroccan Atlantic Façade

Along the Moroccan coast, swell is generally unrelated to the weather on the coast. It is, most often, the consequence of barometric depressions passing between the Azores Archipelago and Iceland. North Atlantic swells are the most frequent, and they are characterized by fairly long wavelengths (period of 10–18 s) and are refracted on all or part of the continental shelf. In this context, the aim of the study is to compare Boussinesq and Birkhoff theories for the calculation of port agitation in two harbors: Casablanca and Jorf Lasfar. The comparison is done based on two models for the calculation of port agitation: The first model is based on the Birkhoff equation (MIKE 21 EMS) obtained from the potential swell theory, and the second is based on the Boussinesq equation (MIKE 21 BW). First, an analysis of agitation limit conditions for vessels in the ports is performed, then time series of offshore sea states are analyzed, and the propagation of the reconstructed sea states is performed, after which simulation scenarios are chosen. The research shows that Boussinesq waves are adequate to be used with long wavelengths swells and that Birkhoff theory MIKE 21 EMS is more pertinent to be employed in smaller coastal locations, where diffraction and wave breaking are critical, and the forcing wave conditions can be represented by a monochromatic and unidirectional wave. This phenomenon is important enough to be studied as it leads in guaranteeing good circulation conditions for ships which are very sensitive and important ships, and its simulation using pertinent theory helps provide optimal solutions leading to allow good harbor conditions.