波流共同作用下潮滩剖面沉积物和地貌分异规律——以长江口崇明东滩为例

通过对崇明东滩两个海滩剖面、表层沉积物和悬沙粒度以及同步水沙资料的分析，探讨波流共同作用下表层沉积物和地貌的分异规律。受波流共同作用的影响，表层沉积物中值粒径由破波带向两侧逐渐变细，分选由破波带向两侧逐渐变差，偏度由极正偏变为正偏，峭度由很窄尖变为宽平和中等峭度。由破波带向岸方向，流速逐渐减小，含沙量逐渐增加。悬沙和表层沉积物粒度特征的对比分析表明，潮间带上部的悬沙主要来源于破波带泥沙的再悬浮。破波带内泥沙以“波浪掀沙”引起的分选运移为主，而破波带两侧的泥沙以潮流对破波带水体的“平流输移”为主。以潮汐水位和高精度海滩剖面数据对崇明东滩微地貌类型按高程进行了新的划分。

Sediment and Geomorphology Differentiation of Tidal Flat Profiles Combined Wave and Current Actions:a case of the east Chongming tidal flat,Changjiang Estuary

Based on the data of two tidal flat profiles,surface sediment and suspended sediment grain-size,current velocity and suspended sediment concentration in the east Chongming tidal flat,the sediment and geomorphology differentiation of tidal flat profiles combined wave and current actions were analyzed.The results showed that the surface sediment D50 decreased gradually from the surf zone to the near shore and outer sea.The sorting of the surface sediment increased,and the skewness changed from very positive to positive,and the kurtosis changed from very leptokurtic to platykurtic and mesokurtic.The current velocity decreased and the suspended sediment concentration increased from the surf zone to the near shore.The comparative analysis of suspended and surfacial sediment grain size showed that the suspended sediment in the upper of intertidal zone mainly came from the sediment resuspension of the surf zone.The selective transport due to the sediment uplift by wave dominated the sediment transport in the surf zone,and the sediment horizontal transport by tidal current dominated the sediment transport in the near shore and outer sea beside the surf zone.The microgeomorphic units of east Chongming tidal flat were divided based on the discussion of the water level and accurate elevation recently.