Abstract
Wave farms consisting of tens to hundreds of devices have the potential to alter the nearshore wave and flow field when located in close proximity to the coast. As a result, wave farms may alter sediment transport pathways and may cause the beach to erode or accrete. Understanding such coastal impacts by wave farms requires a detailed understanding of how wave farms alter the nearshore hydrodynamics. This work presents a first effort to improve our understanding of changes to the nearshore wave field and circulation patterns induced by wave farms. For this purpose, a recently developed wave-resolving non-hydrostatic wave-flow model, which captures the relevant physical processes realistically, was used to simulate the impact of a moderately sized wave farm on the nearshore wave and flow field. Four different scenarios were considered, with the same wave farm consisting of 10 devices, subject to the same realistic sea state, but located at different off-shore distances (1-4 km). The considered wave farm resulted in a reduction of the wave height of up to 40% in its direct lee. This wave shadow extended up to the shoreline, where alongshore gradients in wave energy forced circulation patterns that converged in the direct lee of the farm, where the flow diverged in off-shore direction. Such patterns were observed for all off-shore farm distances, but changes to the nearshore wave and flow field reduced for farms located at greater off-shore distance. Further work will focus on how changes to the nearshore hydrodynamics vary for different wave farm designs (e.g., number of devices, and inter-device spacing) and incident wave conditions (e.g., wave heights and directional spreading). Overall, this work demonstrated the suitability of the recently developed wave-resolving model to study the coastal impact by wave farms.