Numerical investigation of the effects of coastal vegetation zone width on wave run-up attenuation

Coastal vegetation is capable of reducing wave run-up and protecting coasts from flooding and land loss. This study numerically investigates the effect of width of emergent rigid vegetation on wave run-up attenuation. The numerical model is based on two-order fully nonlinear Boussinesq equations and solved using a combination of finite difference and finite volume methods. Physical laboratory data pertaining to long period wave run-up on a bare and emergent vegetated sloping beach is used to validate the accuracy of the model. Next, based on the model, the effect of vegetation zone width on wave run-up attenuation is investigated. The numerical results indicate that coastal vegetation can considerably decrease the wave height and wave run-up, and the wave run-up decreases monotonously with increase in the vegetation width. Moreover, the reduction rates of the wave height and wave run-up, caused by the vegetation zone, demonstrate an overall increasing trend with increase in the wave period when the ratio of vegetation zone width and wave length is constant.