GRAIN SIZE CHARACTERISTICS OF SURFICIAL SEDIMENTS AND THEIR RESPONSE TO HYDRODYNAMICS OVER THE COASTAL WATERS OF NORTHERN JIANGSU PROVINCE

Abstract

Surfical sediment samples were collected from the radial tidal ridge areas and tidal flats on the Jiangsu coast during September to November 2007.The moment grain size parameters(i.e.mean size,sorting coefficient,skewness and kurtosis) are obtained by grain size analysis,and cluster analysis was carried out for the parameters.The result indicates that water depth being shallower than 9 m,sediment samples can be grouped into the same type.Likewise,when the water depth is more than 20 m,sediments belong to another type.However,if the water depth is between 9 and 20 m,there are various types of sediments.Grain size trends obtained using the Gao-Collins model show that there is general trend of transporting towards the central part of the coast,except for the Waimaozhu sandbank.Such a pattern is consistent with the measured sediment transport pathways reported in literature.On the basis of an analysis using the Sternberg diagram,the effect of differential sorting during sediment transport is the main process for the distribution of surficial sediments.The sediments are almost entirely transported in suspension from the Sheyang estuary towards the Dafeng tidal flat,while only around 60% of the sediments are transported in suspension from the Xiaomiaohong channel to the Dongzao tidal flat.This process results in the unified sediment grain size parameters for the surfical sediments between the Sheyang estuary and the Dafeng tidal flat,and different sediment grain size parameters between the Xiaomiaohong channel and the Dongzao tidal flat.