Abstract: Based on the analysis of the grain size characteristics of the sediment in Nanhui joinit area between Changjiang and Hangzhou bay, the net transport trends in Nanhui area are studied by using “Gao and Collins” model. The results are shown: (1)The trend is similar to the distribution of the grain size parameters including the medium grain size, the sorting coefficient and skewness, where the relationships of three parameters have a strong correlation; (2) The grain size characteristics in Nanhui exhibit positively skewed and poorly sorted with a value concentrated around 2. The distribution regions of the sediment with fine grain size (<0.01mm) are located in Nanhui area except for the regions including medium is distributed sector of Momaosha, Nan Huizui and nearshore zone in Luchao harbor where coarse sediment (>0.01mm); (3) Combined “GaoCollins” mode with the characteristics of the dynamics and sediment in Nanhui, it's indicated that the sediment transport patterns are from the north to the south in East bank, but the sediment transport trends in Nan bank should be further analyzed because of the conditions of the complex dynamics in Nan bank.

Key words: grain size characteristics, trends of the sediment transport, Nanhui