潮汐与陆架环流作用下的悬沙输运:江苏新洋港海岸冬季观测结果

Tide and continental shelf circulation induced suspended sediment transport on the Jiangsu Coast:winter observations out of Xinyanggang

细颗粒沉积物在海洋动力的作用下往往会以悬移质形式进行长距离的运动,并在海岸和内陆架产生侵蚀和堆积.废黄河三角洲至江苏中部潮滩系统是研究源—汇过程和产物问题的理想区域.遭受强烈侵蚀的废黄河三角洲作为物源,在沿岸陆架环流和潮流的作用下再悬浮起来的泥质沉积物沿岸输运并最终归宿于江苏中部潮滩.本研究于2013年冬季大潮期间在侵蚀—淤积的过渡带的新洋港岸外开展的全潮水文泥沙观测结果表明,近岸6km内区域的具有高悬沙浓度和强南向沿岸输沙的特征,而距海岸12km站位的悬沙浓度大致为内侧站位的1/3,而悬沙输运单宽净通量比内侧站位小一个数量级.计算估计出冬季大潮沿江苏海岸南下的悬沙通量大致为每天46万吨,这一数值可以和江苏海岸侵蚀岸段的侵蚀量相比较.

Fine sediment can be transported by marine processes in the form of suspended load,resulting in coastal and inner shelf erosion and accumulation.The system of the abandoned Huanghe delta to the middle Jiangsu tidal flat is idealized area for the study of the process-product issues of source-sink systems.The abandoned Huanghe delta suffering severe erosion is the source part of the system.And the fine sediments suspended by the tidal and continental circulation currents were transported alongshore and finally sinked on the middle Jiangsu tidal flat.At the present study,vertical profiles of current velocities,turbidity and salinity were measured on an hourly basis of 25 hours at two stations on the inner shelf out of the Xinyanggang,Jiangsu Coast.The observation results show that,the inner 6km area of the shelf is characterized by high suspended sediment concentration and the strong southward suspended sediment fluxes.However,the suspended sediment concentration and the suspended sediment flux are reduced to 1/3and less 1/10,respectively,at the station about 12 km away from the coast.The southward net sediment flux is estimated as about 4.60×108 kg per day with the winter spring tide condition,which can be compared with the erosion mass of the north part of Jiangsu Coast.