中文摘要：

由于钓口流路行水时期普遍缺乏对河口和近海的系统观测,基于1976年黄河三角洲实测水深数据和汛期水沙数据,采用EFDC三维数值模式对钓口河口泥沙沉积动力过程进行了数值模拟研究。模型结果表明,钓口河口的羽状流和异重流的时空分布具有显著的潮周期变化特征。受与岸线平行的涨落潮流作用,表层羽状流的侧向摆动幅度较大,河口羽状流输沙主要平行于岸线方向,跨等深线的泥沙输运受到限制。汛期黄河入海的高浓度泥沙在钓口河口形成潜没的异重流,在底层沿河口轴线向北输运泥沙至三角洲前缘区域,泥沙输运通量比表层羽状流的输送通量高出一个数量级,且随着离岸距离的增大而呈指数形式快速衰减。随着水深增大,单宽泥沙通量的衰减速率逐渐减小。计算结果显示,由于汛期高浓度泥沙入海,钓口河口的异重流稳定存在,导致约75%的入海泥沙沉积在10m水深以浅的区域,25%的入海泥沙淤积在三角洲前缘外侧,异重流过程对汛期钓口河口泥沙向深水区输运和沉积具有控制作用。数值模拟结果与前人根据水深变化揭示的三角洲冲淤分布格局一致,与钻孔的沉积记录基本吻合。

英文摘要：

A 3-dimensional numerical model was used to investigate the suspended sediment transport off the Diaokou River Mouth of the Yellow River due to the absence of in-situ observations on estuarine sediment dynamics in this area prior to 1976.Two patterns of sediment dispersion were identified as the hypopycnal plume in the surface layer and the hyperpycnal flow in the bottom layer,both showing significant intra-tidal variability due to the interactions between river flow and tidal current.The surface river plume（hypopycnal）was deflexed laterally by the coast-parallel tidal current,which induces significant alongshore sediment transport but limited cross-shore sediment transport.River delivery of high-concentrated sediment in the flood season produces plunging hyperpyucnal flows at the Diaokou River Mouth that acts as a conduit for the northward sediment delivered to the deltaic front.The hyperpycnal flow results in higher sediment flux in the bottom layer than the contribution of surface hypopycnal plume by one order in magnitude.Meanwhile,the hyperpycnal-induced flux exponentially decreases along the subaqueous slope off the river mouth.Approximately 75% of the river-delivered sediment was deposited in the nearshore area shallower than 10 m,whereas the rest 25%of sediment was transported to the deltaic front.These highlighted the dominant role of the estuarine hyperpycnal process in cross-shore sediment transport.The numerical results agree with the previous conclusion on the accumulation-erosion pattern off the Diaokou River Mouth based on the bathymetric changes,and are also consistent with the analysis of sediment records in this area.