Bioengineering is a novel way to reduce the application or dimensions of hard constructions. In the Dutch Noordwaard polder a vegetation field is proposed in front of a planned dike to damp waves such that the desired dike height can be reduced. To investigate the impact of vegetation on waves, the description for wave attenuation as derived by Mendez and Losada (2004) was implemented in the wave model SWAN. The SWAN-VEG model was tested by performing a sensitivity analysis and by calibration and validation on experimental flume data. The model showed expected behavior and calibrated values for the drag coefficient gave reasonable correlations between predicted and measured wave attenuation, except for a plant with flexible floating leaves. Application of the model to the Noordwaard polder showed that a field of willows is able to reduce wave heights by 70% under extreme conditions. This allows a lower dike that fits better into the landscape while maintaining the required safety standard.