Process based modelling of breaker bar evolution with submerged vegetation under regular waves

This study investigates how submerged vegetation influences breaker bar development using the process based IH2VOF-SED model, which couples a two-dimensional vertical Reynolds averaged Navier–Stokes solver with sediment transport and bed evolution. The model is evaluated against laboratory measurements for bare and vegetated beach profiles under regular erosive waves. It reproduces the principal measured features of wave transformation, pointwise velocity signals, and beach-profile evolution, although agreement varies among cases and variables. When vegetation is positioned near the beach toe, the vegetated cases show pre-breaking wave transformation together with reduced hydrodynamic forcing and smaller bar–trough features. When a short meadow is located within the breaking region, pre-breaking wave attenuation is limited and the overall bar–trough scale changes less. Instead, the results support a mechanism in which vegetation-induced changes in the near-bed flow and sediment-transport gradients are associated with a shoreward redistribution of the breaker-bar morphology. Parametric simulations further show that increasing plant density or leaf width increases the prescribed vegetation resistance and is accompanied by progressively shoreward-displaced morphodynamic features, with a reduced incremental response at higher resistance within the tested range. Overall, the results demonstrate the capability of the process-based framework to reproduce the principal stages of breaker-bar evolution and to examine the hydrodynamic and sediment-transport changes associated with the spatial response of the breaker-bar morphology under vegetated conditions.