A one-dimensional model for bed-boundary layer particle exchange

This paper discusses the coupling between transport processes in fine-grained sediment beds and those in the overlying boundary layer. A review of currently available, separate bed and boundary-layer models indicates that they do not constitute a basis for a complete description of these couplings. Consequently, new boundary conditions and nonlocal transports terms for resuspension are proposed in order to obtain satisfactory coupling between suspended and bottom sediments. The nonlocal transport can account both for resuspension from a finite surficial zone of sediment and its redistribution in the boundary layer. Profiles of total suspended matter generated with this new model resemble those observed in marine environments. Application to a suspended matter profile from the Oregon Shelf suggests that this sediment is resuspended at a mean rate of about 0.4% per day to a mean height of about 3 cm. This material is then redistributed by eddy mixing to produce a classic profile that decreases with height above the bed.