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 rev iew of currently available, separate bed and boundary-layer models ind icates 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 sat isfactory coupling between suspended and bottom sediments. The nonloca l transport can account both for resuspension from a finite surficial zone of sediment and its redistribution in the boundary layer. Profile s of total suspended matter generated with this new model resemble tho se observed in marine environments. Application to a suspended matter profile from the Oregon Shelf suggests that this sediment is resuspend ed 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 clas sic profile that decreases with height above the bed.