EFFECT OF SUBMERGED AQUATIC VEGETATION ON TRANSMISSION COEFFICIENT: NUMERICAL EXPERIENCES WITH THE SWASH MODEL

Coastal protection using Nature-Based Solutions (NBS), such as vegetation, has become a topic of increasing interest, especially due to the rising concerns over coastal erosion, flooding, and sea-level rise. Many studies have explored the reduction of wave height with the presence of marine vegetation. However, our understanding of this attenuation process is still in its early stages. To gain further insights, we assessed wave attenuation by vegetation based on the transmission coefficient. Initially, we compared the transmission coefficient of submerged breakwaters (SBW) between physical experiments and numerical modelling simulations with SWASH. Then, SWASH was used to compare the transmission coefficient obtained in a real beach profile between the SBW and a NBS, composed of aquatic vegetation place seaward to the closure depth. Results show that the transmission coefficient is reduced by about 30% in both cases when the vegetation patch is 200m long. This finding suggests that similar transmission coefficients can be obtained either using a SBW or a NBS, which advises a more in-depth analysis on the use of NBS for coastal protection.