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ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Marine Geoscience
Volume 12 - 2024 | doi: 10.3389/feart.2024.1383726

Monopile-induced turbulence and sediment redistribution form visible wakes in offshore wind farms

Provisionally accepted
Lewis P. Bailey Lewis P. Bailey 1,2*Robert Dorrell Robert Dorrell 2Ina Kostakis Ina Kostakis 3David McKee David McKee 3,4Daniel R. Parsons Daniel R. Parsons 2,5Jon Rees Jon Rees 6James A. Strong James A. Strong 2,7Stephen M. Simmons Stephen M. Simmons 2Rodney M. Forster Rodney M. Forster 2
  • 1 University of Calgary, Calgary, Canada
  • 2 University of Hull, Hull, Yorkshire and the Humber, United Kingdom
  • 3 University of Strathclyde, Glasgow, Scotland, United Kingdom
  • 4 Tromsø University College, Tromsø, Troms, Norway
  • 5 Loughborough University, Loughborough, United Kingdom
  • 6 Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Lowestoft, United Kingdom
  • 7 National Oceanography Centre, Southampton, United Kingdom

The final, formatted version of the article will be published soon.

    Offshore wind farms are becoming an increasingly common feature in the marine environment as a renewable energy source. There is a growing body of evidence on the effects of wind farms on the seabed and its organisms. However, an important and understudied aspect of site development is the interaction of turbine foundations on the surrounding marine environment. Structures exert significant disturbance on tides, waves and currents; these are visible as optically-distinct, elongate wakes at the sea surface with elevated suspended particulate matter. Despite this, there is uncertainty on the mechanisms that lead to the visible manifestation of wakes at turbine foundations, primarily due to a lack of direct measurements. Here, in situ measurements along with a 15-year time series of satellite images of the Thanet offshore wind farm, located within the Thames Estuary, were used to investigate the formation of visible monopile wakes, and the effects these have on the surrounding water column. We show the optically distinct wakes are near-constant at Thanet; visible in >90 % of all satellite images, yet no regional change in sea surface turbidity could be attributed to wind farm construction or operation. Monopile wake in situ water samples and acoustic Doppler current profiler (ADCP) backscatter measurements demonstrated colour change related to elevated sea surface sediment concentration. However, averaged water column measurements of suspended sediment within wakes, and upstream of monopiles, remained consistent. These measurements demonstrate that sediment was redistributed towards surface waters, rather than additional sediment becoming suspended in the wake. ADCP velocity measurements supported a mechanism of sediment lofting towards the surface, with enhanced vertically upwards flow recorded in wakes.

    Keywords: Offshore wind farms, Hydrodynamics, Turbid wakes, Suspended particulate matter, In situ measurements

    Received: 07 Feb 2024; Accepted: 22 Jul 2024.

    Copyright: © 2024 Bailey, Dorrell, Kostakis, McKee, Parsons, Rees, Strong, Simmons and Forster. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Lewis P. Bailey, University of Calgary, Calgary, Canada

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.