Sediment transport pathways and organic carbon burial impacted by offshore wind farms in shelf seas

Abstract The rapid expansion of offshore wind farms increasingly impacts ocean environments. Little is known concerning synergistic effects of wind farms on large-scale sediment transport and seabed ecosystem functioning. Here, by using a three-dimensional hydro-morphodynamic model integrating wake effects, we assessed wind farm impacts on regional-scale sediment transport and organic carbon sedimentation in the North Sea. Results suggest that wind farms can alter net sediment transport fluxes by up to 30% locally, reduce mud accumulation in established depocenters and create new depocenters through long-term accumulative effects. These shifts, driven by changes in stratification and residual currents, redistribute up to 1.5 million tonnes of mud and 0.07 million tonnes of particulate organic carbon annually. Wind farms also retain ~1.5% of annual riverine sediment input to the ocean, affecting connectivity with nearshore systems like the Wadden Sea. These findings underscore the need to consider the system-wide impacts in marine spatial planning.