Numerical modeling of particulate transport under combined current-and-wave action along coastal areas

The study of the transport of particles in coastal areas is of importance with regard to coastal morphodynamics and pollutant transport. This study focuses on fine particles (i.e. clay and biofilm-covered microplastic particles) which have the tendency to stick together and aggregate to form flocs which settle faster than the original individual particles. An important implication of greater settling velocities of suspended sediment is the formation of fluid mud layers on the bottom of coastal areas (examples and potential applications include the mud banks along the Amazon-Orinoco coastline; e.g. Gratiot & Anthony (2016)), and high benthic sediment concentrations observed along the Belgian coast (Fettweis & Baeye, 2015)). In this study, flocculation with be modeled using the multimodal particle size distribution method by Lee et al. (2014). Particular attention will be given to the influence of the combined action of waves and currents on the floc properties and their interaction (deposition and erosion) with the fluid mud layer in the case of cohesive sediments and the organic-rich bottom surface layer (including marine snow) in the case of microplastic particles.