Protecting intra-coastal fairways from ship waves using living shorelines techniques: A full scale experiment

This study evaluates the effectiveness of applying living shoreline techniques for protecting reed belts and eroding bluffs in an intra-coastal fairway with intense traffic by ocean-going vessels. The re-establishment of the reed belt can be explained by the dissipation of the hydrodynamic forces by the sill structure. There is a negative relationship between vegetation growth and wave exposure due to washout from the rhizome layer and destabilization of the reed belt fringe by excessive wave forces. A stabilizing structure in front of vegetation may reduce the washout of seeds and promote the establishment and survival of sprouts. The stabilization of the bluff can be explained by that the protective measure reducing waves attacking the bluff base. Waves attacking the bluff base are one of the dominant processes for bluff erosion. In this study, the wave forces were reduced by the sill and the vegetation on the foreshore, in combination with elevated the bluff base due to the foreshore. After reinforcing the sills in September 2019 there has been no need for maintenance of the protective measures. The results after a four-year study period indicate reed growth can be promoted by installing a sill parallel to the shore and that eroding bluffs can be stabilized by creating a vegetated foreshore in front of the bluff combined with a shore parallel sill. This study showcases the potential of using living shoreline techniques in fairways exposed to intense ship traffic from larger vessels to promote reed growth and reduce bluff erosion.