Study on the Characteristics of Temporal and Spatial Changes in Properties 〖JZ〗 of Surface Sediment on NearShore Seabed of StrongTide Bay:a case from the north bank of Hangzhou Bay in Shanghaia

Key words: 
• Hangzhou Bay /
• surface sediment /
• temporal and spatial variation /
• hydrodynamics

Abstract: Grain size parameter is the most important information of sediment, which can point out the characteristics of distribution and transportation. Based on analysis data of 167 samples which were collected from the north coast of Hangzhou Bay in June 2005 and December 2006, a study on the rules of temporal and spatial changes in properties of seabed surface sediment in strongtide bay is conducted. As well as, through the Grain Size Transport Analysis model, a conveying trend analysis of sediment in this basin has been studied, in the base of which a research of sand sources is primarily discussed. Finally, the response process of tidal flat sediment to the highenergy hydrodynamic environment is also analyzed. The results indicate that: (1) The grain size of tidal flat sediment in north coast of Hangzhou Bay is generally small, and silty clay is the main sediment types in this basin; (2) The vertical difference of grain size characteristics is more obvious than the transversal, and also there is some seasonal variation between flood season and withered season; (3)The results of GSTAmodel show that，the sediment of this basin is mainly from the upstream and the sea waters. As well as , the interregional sediment exchange is another important method to get the balance of sediment supply in this basin；(4) Agency coverage where tide current can stir surface sediment is mostly the Nanhui and Fengxian water area, while the wave stirring agency coverage almost covers the whole section of the research basin, on which the wave height below 1.5m effect most significantly.