MODELLING MARINE DUNES INTERACTING WITH A WIND FARM OFFSHORE DUNKIRK

Current and future offshore wind farm (OWF) projects are likely to be deployed in shallow shelf seas due to the proximity to mainland and favourable depths. Shallow shelf seas are also home to large sedimentary bed forms called marine dunes (sometimes sand waves). Their scale and the continuous evolution of the seabed resulting from their dynamic behaviour are expected to pose challenges for the implementation and safety of OWF projects. However, the morphology and dynamics of dunes are still poorly understood in open marine environments. Our interest is in an area offshore Dunkirk (northern coast of France), where marine dunes coexist with sandbanks. The area is subjected to relatively strong tidal flows, and waves originating from the Atlantic Ocean and the North Sea. Recurrent and detailed bathymetric surveys have been carried out in recent years. They indicate migration rates of up 30 m/year.