Abstract: Based on the field observation data of current velocity and suspended sediment concentration (SSC) measured in the upper reach of North Channel in the Changjiang Estuary from 15th April to 24th April in 2018, the vertical distribution patterns of SSC during the neap and spring tides are studied. The results show the SSCs in the study area were relatively low, with the mean value of only 0.17 kg/m3. SSCs were higher in spring tide than in neap tide, and close to each other for the flood-mean and ebb-mean values. Tidal currents were much stronger in spring tide than in neap tide, and in ebb phase than in flood phase. Salinity was considerable low during the survey period, with the mean value of only 0.16 psu. The neap-spring variation, flood-ebb variation and vertical variation of salinity were all very small, indicating the impact of salinity-induced stratification on the SSC profile is negligible. In such hydrodynamics, sediment dynamics and salinity condition, the SSCs profiles during the spring tide were the linear type and exponential type. But during the neap tide the SSCs profiles were the linear type, vertical-line type and exponential type, and the linear profile was the dominant type. By fitting Rouse equation, we found that most of measured SSCs profiles fitted Rouse equation roughly, and the settling velocity of suspended sediment deduced by this equation is between 0.36-2.89 mm/s.
Soulsby equation can accurately predict the observed linear and vertical-line types of SSC profiles, with the average error less than 10%.