Suspended Sediment Transport Characteristics In Offshore Area Of Yangtze Estuary

Nearshore waters of Chongming eastern beach, is one of the most sensitive regions in the Yangtze River estuary. With the background of the Three Gorges Project, South-to-North Water Diversion Project and Deep Water Channel Project in Yangtze Estuary, this paper use the data of four times oceanographic survey between 2009 and 2010, Simply summarize the distribution law of suspended sediment and the characteristics of water and sediment transport, analyze the forming reason and the influence to sedimentary environment.The result showed:(1)The logitudinal distribution of the suspended sediment concentration (SSC) in nearshore water area of Chongming eastern beach is lower in west and higher in east, and the main influencing factor is velocity and terrain. (2)The SSC is a gradual growth from surface to bottom. (3)The peak of the SSC in whole tidal cycle mainly appear Twin Peaks form, the main reason is high velocity and salinity intrusion and vertical gravitational circulation. (4)Generally, The SSC during the spring is higher than during the neap. With the effects of wind waves and flocculation. (5)SSC in dry season is higher than that in flood usually. (6)Due to the amount of water and sediment from the Yangtze river decrease, SSC in summer in 2009 is lower than that in 1982, however, the average SSC in dry season of 2010 is higher than that in 1982, the main reason is terrain, hydrodynamic condition and human activity. (7) There is a close link between residual current, sediment and water discharge per unit width, but residual current direction can't Substitute the sediment discharge direction per unit. (8) Offshore region and North Channel is important source to Chongming eastern beach.