Temporal variations in concentration and transport of suspended sediments in a channel–flat system in the Ems-Dollard estuary

Observations of suspended sediment concentration (SSC), currents and water levels above a tidal flat and in a nearby channel in the Dollard basin in the Ems-Dollard estuary are used to derive general characteristics of variations in SSC and the transport of suspended sediments in a channel-flat system in the Wadden Sea. Tidal currents show a strong ebb dominance which is caused by the large intertidal flats in the Dollard basin. Intra-tidal variations in SSC are limited by the availability of fine-grained sediments resulting in similar concentrations during ebb and flood in the channel. Wind events influence the SSC above the flat much more than in the channel. The net transport of sediments above the intertidal flat appears to be highly variable. Under fair weather conditions there is a relatively small net transport towards the higher levels of the tidal flat. When the wind speed increases the net transport increases drastically. However, the direction of the net transport of sediments is very variable in contrast to the net transport of water.