长江口南港底部边界层特征的观测与分析

对长江口2002年和2003年共4个潮周期的数据进行了分析,通过流速对数剖面公式计算边界层参数,并对各个潮周期内的边界层参数的变化规律进行了分析,同时也对悬沙输送可能对垂向水流结构以及边界层参数造成的影响进行了探讨。结果表明,悬沙的时间分布特征对温度、盐度、水体密度的分布格局有重要影响,主要表现在水体的Rf值普遍较高,分层稳定。此外,悬沙也可影响边界层参数,从而对水流结构产生影响。由于水体的层化作用,使层间的摩擦阻力增大,相当于在垂向上产生不同内边界层,因而影响了流速在垂向上的变化。

Observing and analysing the characteristics of bottom boundary layer in Nangang port in the Changjiang River estuary

Four field investigations of the velocity and suspend concentration of sediments have been carried out by using acoustic doppler current profiler(ADCP) in the Changjiang River estuary.The bottom boundary layer parameters,which have been obtained through regression analysis of tidal cycle,have also been analysed in order to study the relationship between suspended material and flow structure.The results indicated that the vertical distributions of temperature,salinity and fluid density within water body were influenced by the suspended sediment transport and distribution,and the suspended material changes the vertical density gradient,which makes the water highly stratified.The bottom boundary layer parameters were influenced by stratification induced by suspended sediments,subsequently the flow structure was also changed.The stratification increased the friction among different layers which corresponded to forming a internal boundary layer,therefore,the vertical slop of the velocity has been affected.