Abstract: The occurrence of a turbidity maximum is a most common phenomenon in the brackish water re-gions of tidally influenced river.Based on analysis of meaured data,the dynamics of the turbidity max-imum in Yangtze River eatuary is investigated,The evolution patterns of the turbidity maximun duringatidal cycle is shown and analvsed.The time histories of sediment concentrations and current velocityare discussed for characteristic locations within the turbidity maximum。The results derived from timeseries show that the deposition and resuspension of sediment is the dominant Drocess in the turbiditymaximum and that the advection of particals is the dominant process,at marginal zones during well-de-fined times of the cycle,The analyses also show that the suspended sediment settles significantly in themiddle and lower reach during the low water slack and in the uppor and middle reach during high waterslack.Rapid settling of suspended sediment is asseeiated with the water body at salinities ranged from 5‰ to 1 5‰. This reflects that the effect of salt flocculation may be significant around slack water.

Key words: turbidity maximum, suspended sediment dynamics, Yangtze River estuary

摘要： 河口最大浑浊带是发生在潮汐河口盐淡水交汇区的最普遍现象。本文在现场资料分析的基础上,对长江口最大浑浊带的悬沙运动特征进行了研究。本文分析了最大浑浊带的随潮变化模式,对最大浑浊带特征位置的含沙量、流速变化时间序列进行了分析讨论。结果表明,泥沙的沉积和再悬浮动力过程是长江口最大浑浊带的主导过程,在潮周期某些时段,泥沙对流搬运在最大浑浊带边缘区域占主导地位,分析结果还表明,落憩时,泥沙在中下段强烈沉积；而涨憩时泥沙在中上强烈沉积。其沉积部位与盐度为５‰至１５‰的水体相一致,说明盐度絮凝在憩流前后影响很大。

关键词: 最大浑浊带, 泥沙运动, 长江口