TY - CONF

T1 - Renewable infrastructure in a field of dunes: changes to near bed turbulence & sediments

AU - Unsworth, Christopher

AU - Austin, Martin

AU - Van Landeghem, Katrien

AU - Couldrey, Amelia

AU - Whitehouse, Richard

N1 - Conference code: VII

PY - 2023/1/1

Y1 - 2023/1/1

N2 - The world’s shallow continental shelves are currently experiencing a rapid pace of development from the growth of offshore renewable energy. Our ability to predict the response to new seabed infrastructure is limited by our models of flow and sediment transport which were created and validated assuming a uniform flow structure. We present field results from a deployment in the eastern Irish Sea where profiles of flow and turbulence were measured and used to drive a range of suspended sediment models. The range of models, and the various ways of forcing them, are tested against measured suspended sediment concentrations from a calibrated multi-frequency acoustic backscatter system. It was found that the bed shear stress as measured via 2D depth averaged approximations (with velocities from a bed mounted ADCP), as well as the TKE method (from a near bed ADCP) was the most accurate, whilst law of the wall approximation performed poorly. We found that the method of Garcia and Parker (1992) family of methods produced the most accurate measure of suspended sediments. Transport near the threshold of motion (30% of measurements) was poorly represented by all combinations of methods. The highest suspended sediment concentrations (10% of measurements) were also poorly predicted, likely due to the changing bed level which occurred during these high concentration events

AB - The world’s shallow continental shelves are currently experiencing a rapid pace of development from the growth of offshore renewable energy. Our ability to predict the response to new seabed infrastructure is limited by our models of flow and sediment transport which were created and validated assuming a uniform flow structure. We present field results from a deployment in the eastern Irish Sea where profiles of flow and turbulence were measured and used to drive a range of suspended sediment models. The range of models, and the various ways of forcing them, are tested against measured suspended sediment concentrations from a calibrated multi-frequency acoustic backscatter system. It was found that the bed shear stress as measured via 2D depth averaged approximations (with velocities from a bed mounted ADCP), as well as the TKE method (from a near bed ADCP) was the most accurate, whilst law of the wall approximation performed poorly. We found that the method of Garcia and Parker (1992) family of methods produced the most accurate measure of suspended sediments. Transport near the threshold of motion (30% of measurements) was poorly represented by all combinations of methods. The highest suspended sediment concentrations (10% of measurements) were also poorly predicted, likely due to the changing bed level which occurred during these high concentration events

M3 - Paper

SP - 299

EP - 306

T2 - Marine and River Dune Dynamics

Y2 - 3 April 2023 through 5 April 2023

ER -