Turbulent exchange of fine sediments in a tidal channel in the Ems/Dollard estuary. Part I: Turbulence measurements

In-situ high-frequency measurements were made of velocities and suspended sediment concentrations at three levels close to the bed at one location in a tidal channel during a few tidal cycles in June and August 1996. The measurements showed that under unstratified flow conditions the turbulence characteristics in the tidal channel are comparable to the turbulence characteristics obtained in laboratory flumes at much smaller Reynolds numbers. Effects of sediment-induced density stratification on the turbulence properties occurred at higher levels in the water column during those parts of the tidal cycle when flow velocities were relatively small and/or concentrations were relatively high. Effects of density gradients showed a decrease in correlation between streamwise and vertical velocity fluctuations and in a decrease in the streamwise integral length scale.