Stationary and vessel mounted ADCP profiles from flow and suspended sediment concentration fields over tidal bedforms in the Knudedyb tidal inlet in the Danish Wadden Sea

In the Danish Knudedyb inlet, very large primary bed forms remain ebb-oriented during a tidal cycle while smaller superimposed bed forms reverse direction with each tidal phase. Hydroacoustic in situ observations reveal pronounced differences in suspended sediment transport patterns between tidal phases caused by the relative orientation of primary bed forms and the mean tidal flow and flow unsteadiness during a single tidal phase.

When flow and primary bed form orientation are aligned, water-depth-scale macroturbulence develops in the bed form lee-sides in the presence of flow separation. Macroturbulent flow structures occur at high flow stages and are coupled to increased amounts of sediment in suspension. When flow and bed form orientation are opposed no evidence of flow separation associated with primary bed forms is found.