Sediment Transport in Silt-dominant Coasts: The Suspended Sediment Concentration and Modeling Approaches

Silt-dominant coastal areas are widely found. Silty sediment is sensitive to wave-current interaction, as it is easily to be stirred up and resettled down and thus causes heavy sediment transport. This kind of sediment has drawn much attention from researchers in recent years. Field datasets were collected in the northwestern Caofeidian sea area and Huanghua port sea area, where the bed materials are silt-dominated, in Bohai Bay, China. The measured data shows that, the suspended sediment concentration (SSC) is mainly affected by wave-induced sediment suspension: in the northwestern Caofeidian sea area, under light wind conditions the SSC was very low; the SSC increased continuously under the gales over 6-7 in Beaufort scale, which was about 3-6 times the value under light wind conditions. The density distribution of water-sediment mixture showed that there was rarely little fluid mud in the study area. To describe the SSC changes during wave events, several approaches were presented, including the sediment diffusivity, stratification effects, hindered settling and mobile bed effects etc. These approaches were used to evaluate the measured concentration in the northwestern Caofeidian sea area and Huanghua port sea area during wave events. Results show that, the proposed approaches can properly simulate the changes of SSCs due to wave events.