Observed and Predicted Vertical Suspended Sediment Concentration Profiles and Bedforms

J. J. Williams, P. S. Bell, P. D. Thorne, K. Trouw, P. J. Hardcastle, J. D. Humphery

Abstract


Measurements of hydrodynamic conditions and vertical suspended sediment concentration profiles, C-profiles, have been obtained above rippled sandy beds in a large wave flume. Measured values of wave height and period, water depth and sediment properties are used in well-known formulae to predict sediment dynamics and bed shear stresses due to waves. These data are then used in an existing convective model and a new model to predict C-profiles. Measured C-profiles and C-profiles predicted by the new model are shown to agree well for a range of grain sizes and wave conditions. Grain-scale bed roughness, defined using data from the model, is found to vary with the wave mobility number. Values for the wave mixing coefficient derived using the new model are tested and are found to agree well with published values and with theory.


Keywords


Deltaflume; pump-sampling; hydraulic roughness; diffusion; vortex; diffusivity; wave mixing; acoustic bed imaging

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