• The XBeach phase-averaged wave model is extended and coupled with an emergent flexible vegetation dynamic model • A drag coefficient formula is proposed for wave attenuation by emergent flexible vegetation dynamics using a genetic programming algorithm • Damping coefficient and drag coefficient are related to several nondimensional parameters • The influence of relative vegetation height on wave attenuation is relatively greater under conditions of higher vegetation stiffness Wave attenuation by flexible vegetation is attracting increasing scholarly attention due to its coastal protection and ecological benefits. Although satisfactory progress has been made in understanding flexible vegetation dynamics and the resulting wave attenuation, existing numerical studies are primarily limited to the assumption of submerged vegetation. This study set out to establish a numerical simulation method for wave attenuation by emergent flexible vegetation and to investigate the corresponding wave attenuation characteristics. To this end, the XBeach phase-averaged wave model was extended by incorporating the emergent flexible vegetation dynamic model. The performance of this extended model in simulating wave attenuation by emergent flexible vegetation was validated against conducted flume experiments. Experimental results indicated that increasing wave steepness, drag-to-stiffness ratio, relative wave height (wave height/water depth), and relative vegetation height (stem length/water depth) generally resulted in higher damping coefficients. A new drag coefficient formula accounting for vegetation flexibility and relative vegetation height was developed using a genetic programming algorithm. Within the parameters utilized in this investigation, simulation results demonstrated a positive relationship between the damping coefficient and the relative vegetation height, and this relationship was stronger under vegetation conditions with higher stiffness. These findings expand the applicability of numerical models for vegetation–wave interactions while contributing to a better understanding of wave attenuation by emergent flexible vegetation.
Yin et al. (Thu,) studied this question.