长江口浑浊带核心区北槽水动力特征研究

本文根据2015年长江口洪季浑浊带水域座底三脚架全水深范围观测数据,对北槽中下段纵横向流、余流结构、边界层特征等进行了深入研究,结果显示:（1）大潮潮流矢量特征在垂向上的变化差异最为显著;北槽中下段水流出现明显的横向输移,指向航槽北面;（2）横向流速在大潮期间的变化（垂线平均）为-0.10~0.39 m/s,小潮期间的变化为-0.13~0.25 m/s;横向平流对于北槽纵向物质输运有显著调整作用;（3）余流垂向差异大,底部几乎为0,小潮期间余流更强;周期性再悬浮的细颗粒泥沙可作为北槽最大浑浊带的重要物质来源;（4）传统六点对数流速拟合法获得摩阻流速误差较大,近底1 m区域高分辨流速剖面是准确获取底边界层参数的有效途径。

Analysis of hydrodynamic features of the North Passage in the turbidity maximum, Changjiang Estuary

Based on the observations of full depth in the North Passage (NP) during the flood season in 2015, an analysis of horizontal flow, residual flow structure and boundary layer features in the middle-lower sections of NP was further conducted. The research reveals that the tidal current vectors during spring tide shows clear vertical variations. A lateral water transport to the north of the channel appears in the study site. The lateral flow velocity (depth-averaged) varies from -0.10 m/s to 0.39 m/s during spring tide while -0.13 m/s to 0.25 m/s during neap tide. Lateral advection plays an important role in the longitudinal mass transport and hydrodynamics. There is a significant variation in the residual flow vertical distribution, with an approximately zero value at the bottom. The residual flow is stronger in the neap tide. Suspended bed sediments can be seen as a supply for the turbidity maximum. There are great errors in the logarithmic velocity fitting law based on the traditional "six points" method. To gain the precise bottom boundary layer parameters, we need to focus on the high-resolution velocity profile in the 1 m water column above the bed.