J.H. Damveld1*, E. de Borger2, B.W. Borsje1, S.J.M.H. Hulscher1, K. Soetaert2
1 University of Twente; 2 NIOZ
In sandy coastal seas, such as the North Sea, tidal forces cause the formation of sand waves. These bedforms can grow up to 10 meters in height and hundreds of meters long, and migrate several meters per year. Variations in physical parameters and food availability along these sand waves lead to a high heterogeneity of habitats on a small spatial scale, where particularly the troughs house a surprisingly high amount of benthic organisms (Damveld et al, 2018). The increasing number of offshore windfarms (OWFs) will lead to cascading effects both during the construction phase (immediate impact) and the operational phase through alterations of local currents, sediment transport and, consequently, morphological patterns (chronic impact) (Rivier et al., 2016). Within Footprint we aim to investigate this interplay between dynamic bedforms and hard structures.
During the summer of 2022 we carried out a field sampling campaign around the Dutch-Belgian OWF (Figure 1). In this campaign three research vessels collaborated to study the hydrodynamic patterns, water column suspended matter characteristics (SPM), and sediment oxygen consumption, in and around the OWFs, and on the sand wave fields present in this area. During the conference we will present the first results from this sampling campaign, with a focus on the hydrodynamic and SPM results from the Dutch side of the windfarm area.
Figure 1: NIOZ research vessel Pelagia close to the Borssele OWF area near the Dutch-Belgian border, location of the 2022 summer sampling campaign in the Footprint project.
Damveld, J. H., van der Reijden, K. J., Cheng, C., Koop, L., Haaksma, L. R., Walsh, C. A. J., Soetaert, K., Borsje, B. W., Govers, L. L., Roos, P. C., Olff, H. & Hulscher, S. J. M. H. (2018). Video Transects Reveal That Tidal Sand Waves Affect the Spatial Distribution of Benthic Organisms and Sand Ripples. Geophysical Research Letters, 45(21), 11837-11846. Doi:10.1029/2018gl079858
Rivier, A., Bennis, A., Pinon, G., Magar, V. & Gross, M. (2016). Parameterization of wind turbine impacts on hydrodynamics and sediment transport. Ocean Dynamics 50. Doi:10.1007/s10236-016-0983-6