南汇嘴潮滩沉积物粒度特征研究

文中以实测底质采样资料为基础,对南汇嘴沉积物粒度特征进行了分析,并利用Gao&Collins沉积物趋势分析法探讨边滩的沉积物输运趋势。总体上看,样品粒级变化不大,主要以粘土质粉砂、粉砂为主。没冒沙区域由于受到特殊地形以及水流的影响,沉积物以细砂为主;南汇东滩在横向分布上,沉积物粒径逐渐变粗再逐渐变细;南滩受风浪影响,近岸浅滩沉积物颗粒组成较粗,而远岸区域海床颗粒较细。沉积物中值粒径、分选系数和偏度的分布具有一致性,三者相关性较强;浅滩的沉积物粒度特征表现为正偏,分选性较差,分选系数值集中在2左右;南汇嘴区域沉积物运移方向主要是从口外向西输移,汇聚在南汇嘴附近;杭州湾北岸沉积物主要是向东输运,达到芦潮港西侧水域后逐渐转为向南或向南偏东离岸方向运动,对芦潮港附近水下岸坡的冲刷后退起到了一定的影响。

Hydrodynamic explanation and characteristic of sediment granularity of Nanhuizui foreland in Changjiang Estuary

The grain size characteristics of the sediment were analyzed and the sediment net-transport trends were studied by using Gao & Collins model.The results are shown:the sediment granularity level changes little,mostly including clayey silt and silt;the minority is fine sand because of the special landform and current in the area of Meimaosha;the horizontal distribution of sediment granularity takes on "fine-coarse-fine" in the Nanhui east shoal,but because of storm waves,the grain is coarse relatively in nearshore and fine in offshore in south shoal;the trend is similar to the distribution of the grain size parametera including medium grain size,sorting coefficient and skewness,which have obvious relationships;the grain size characteristics in Nanhui exhibit positive skewness and poor gradation which focus on 2.0;the sediment transport trend is from offshore to the mouth in Nanhui,and to the east in the north bank of Hangzhou bay but to the south or the south by east off shore in the west area of Luchao harbor,which act on the erosion of submerged shore.