Dynamic dunes study
A study to help offshore wind farm development has found underwater dunes in the Dunkirk area of France are very dynamic.
The collaborative R&D project DUNES, led by Shom and France Energies Marines and initiated in 2019, aims to improve knowledge on the sedimentary and biological dynamics of dune ecosystems in the area of the future offshore wind farm off Dunkirk and its electrical connection.
Initial results of morphological monitoring “suggest that the underwater dunes in the Dunkirk area are very dynamic: they have moved continuously eastwards over the period studied, with variable migration speeds. Extreme events such as storms seem to influence this horizontal displacement dynamic with a variation in sediment thickness at a given point. These movements will be anticipated in order to optimise the installation and manage the maintenance of offshore wind farms and their electrical connections”.
In order to determine the evolution of the underwater dunes with a high spatial and temporal resolution, 8 bathymetric surveys were carried out between November 2019 and July 2021, at 3 study sites, each covering an area of 1km2.
In addition, a current measurement campaign lasting more than a month was carried out in the spring of 2021, enabling the hydrodynamic processes at work in the area to be monitored.
In order to deepen the work initiated within the framework of DUNES, due to finish in 2022, the collaborative R&D project MODULLES will start at the end of 2021. It will focus on the modelling of long‐term interactions between underwater dunes and the components of future offshore wind farms.
Underwater dunes are relatively common in France off Dunkirk and Le Tréport. Formed by the combined action of marine currents and swell, these sedimentary structures, a few metres high, are highly variable in morphology and can shift.
By Rebecca Jeffrey
