Meteorological Conditions Influence the Migration of a Marine Dune Field in the Southern North Sea

Abstract

A field of marine dunes has been studied in the Southern Bight of the North Sea. These large dunes, 1–5 m in height and several hundred meters in length, are highly mobile: migration rates of up to 30 m/year have been observed in places. The area is dominated by tides and is characterized by strong currents. Winds are predominantly from the southwest and, to a lesser extent, from the north. A large-scale 3D numerical model was used to simulate the migration of this dune field over time. It is based on the process-based opentelemac system. The model has been calibrated and validated against in situ bathymetric data and is therefore suited to our objective: to explore the contribution of weather (wind and atmospheric pressure) to the propagation of large marine dunes, in relation to that of tidal currents. To do this, a 4-month period was simulated, with and without meteorological effects being taken into account in the numerical model. The results highlight the fundamental role of wind conditions in an accurate representation of seabed changes over time. They also show how meteorological events that are different from the prevailing conditions influence the short-term evolution of the dune field.