TY - JOUR

T1 - Exploring regional coastal sediment pathways using a coupled tide-wave-sediment dynamics model

AU - Davies, Alan G.

AU - Robins, Peter

AU - Austin, Martin

AU - Walker-Springett, Guy

PY - 2023/1/15

Y1 - 2023/1/15

N2 - Knowledge of sediment transport pathways is important for coastal management as well as for offshore infrastructure such as wind farms and other renewable energy installations. Here a three-way coupled model of tides, waves and sediment dynamics is presented, which extends theapproach of Davies and Robins (2017) for the prediction of the locally-varying seabed roughness ks resulting from the interaction between the flow (tides and waves) and the bed sediment (grain size mixture) subject to wave-current interaction (WCI) at the seabed. The model was applied to the North Wales coastal area, with particular emphasis on an extensive shore-connected sand bank (Constable Bank), the stability of which was investigated through the study of residual sediment circulation patterns. Multi-beam (MBES) and seabed rig (AWAC) observations have allowed validation of the predicted ks and hydrodynamics, respectively. With due allowance for the supply ofmobile sediment, the agreement between predicted ks and observed bedform height was generally good. The model has been used to determine residual velocities and sediment pathways, both with and without wave effects included. Wave influence and WCI are predominant in nearshore areas,affecting the magnitude and direction of the residual fluxes. A key modelling outcome offshore is a clockwise residual circulation pattern for water and sediment around the end of Constable Bank, set within a generally eastward net drift of sediment in the wider study area

AB - Knowledge of sediment transport pathways is important for coastal management as well as for offshore infrastructure such as wind farms and other renewable energy installations. Here a three-way coupled model of tides, waves and sediment dynamics is presented, which extends theapproach of Davies and Robins (2017) for the prediction of the locally-varying seabed roughness ks resulting from the interaction between the flow (tides and waves) and the bed sediment (grain size mixture) subject to wave-current interaction (WCI) at the seabed. The model was applied to the North Wales coastal area, with particular emphasis on an extensive shore-connected sand bank (Constable Bank), the stability of which was investigated through the study of residual sediment circulation patterns. Multi-beam (MBES) and seabed rig (AWAC) observations have allowed validation of the predicted ks and hydrodynamics, respectively. With due allowance for the supply ofmobile sediment, the agreement between predicted ks and observed bedform height was generally good. The model has been used to determine residual velocities and sediment pathways, both with and without wave effects included. Wave influence and WCI are predominant in nearshore areas,affecting the magnitude and direction of the residual fluxes. A key modelling outcome offshore is a clockwise residual circulation pattern for water and sediment around the end of Constable Bank, set within a generally eastward net drift of sediment in the wider study area

KW - Bed friction

KW - Net sediment transport

KW - North Wales coastal area

KW - Residual flow

KW - Variable seabed roughness

KW - Wave-current interaction

U2 - 10.1016/j.csr.2022.104903

DO - 10.1016/j.csr.2022.104903

M3 - Article

VL - 253

JO - Continental Shelf Research

JF - Continental Shelf Research

SN - 0278-4343

M1 - 104903

ER -