Tidal and seasonal asymmetry of suspended sediment concentration in branched channels of the changjiang river estuary

Due to the influence of runoff and estuarine morphology, asymmetrical phenomena of hydrodynamics, suspended sediment concentration (SSC) and salinity occurs between the flooding and ebbing stage in the estuary. Such a phenomena also shows significant regional and seasonal differences. Based on hydrological survey in July 2013 and January 2014 in the Changjiang River Estuary, it is found that suspended sediment concentration in the branched channels of the Changjiang River Estuary has asymmetric characteristics, which varies with flood and dry season as well as spring and neap tide. In terms of spatial variability, there exists along channel difference, inter-channel difference as well as water colume difference. The evolution of the estuary controlls the overall SSC difference between the North Branch and South Branch. The flood and dry seasons affect the redistribution process of SSC in the estuary. Spring tides has a stronger impact on SSC asymmetry than that of neap tides. Theseasonal wave condition affect the SSC asymmetric distribution in the turbidity maximum zone of the estuary along the north-south direction. The high sediment concentration near the bottom contributes significantly to the SSC asymmetry between flooding and ebbing stages at the river mouth.