Numerical Modeling of Swell Transformation as It Approaches the Coast of Pointe-Noire

Abstract

The aim of this paper was to describe the behavior of swell and its effects immediately offshore and along the coast of Pointe-Noire in the Republic of Congo, using the CMS-Wave model. This is a spectral wave forecasting model based on the wave action equilibrium equation and represents the two-dimensional variation of wave energy. The aim of this study was to understand the directional spectrum of wave energy and its impact on the dynamics of the coastal system in this area. The various test cases showed that the frontal incidence swell has similar effects to the non-frontal incidence swell in the northwest direction, with a slight amplification of wave height as it approaches the coast. For non-frontal swell in the south-westerly direction, wave heights are amplified as they approach the coast. This is because the coastal zone of Pointe-Noire does not receive wave energy in the counter-clockwise direction between 80˚ and 275˚. The swell responsible for the greatest drift observed in this zone is coming from the southwest. As they pass through the immediate coastal zone of Pointe-Noire, waves tend to move northwards. A comparison of wave heights was made between the values obtained by the model and those predicted by marine weather spots on June 23 rd and 24 th , 2024, for validation purposes. The results obtained show that the model simulates waves reasonably well.