Three‐dimensional modeling of tide‐induced suspended transport of seabed multicomponent sediments in the eastern English Channel

Abstract

A three‐dimensional primitive numerical model is developed to simulate the circulation and resuspension of noncohesive sediments in the eastern English Channel. The present model is based on Coupled Hydrodynamical‐Ecological Model for Regional and Shelf Seas (COHERENS) adapted for computing advection‐diffusion of suspended multicomponent sediments. A statistical approach is first applied to interpolate spatial sampled grain size distributions with 11 classes at the computational grid nodes. These data then provide the availability of each class of sediment to be suspended. Finally, they are used to compute different bottom roughness parameters. Time histories of mean current and turbulent variables predicted by the model are compared with field data collected in two shallow sites off Hardelot and Merlimont beaches, in the south of Boulogne‐sur‐Mer (Dover Strait). Comparison of predicted and measured time histories of total suspended sediment concentration (SSC) is conducted at the Hardelot site. The model is used to quantify the respective contributions of SSC of the three grain size classes to resuspension processes. The spatiotemporal evolutions of the different classes in the surrounding area show local and advection‐dispersion controlled remote suspension, both dependent on spatial changes in bathymetry, sediment composition, and coastline geometry.