长江口北港主槽河道悬沙输运空间结构特征分析  

Analytical study on sediment transport space structure characteristics of middle reach of north channel of Yangtze Estuary,China

作　　者：杨忠勇[1] 任鹏 钱门亮 罗铃 范中亚 YANG Zhongyong;REN Peng;QIAN Menliang;LUO Ling;FAN Zhongya(College of Hydraulic and Environment Engineering,China Three Gorges University,Yichang 443002,China;South China Institute of Environmental Science of MEE,Guangzhou 510530,China)

机构地区：[1]三峡大学水利与环境学院,湖北宜昌443002 [2]生态环境部华南环境科学研究所,广东广州510655

出　　处：《人民长江》2021年第2期1-9,98,共10页Yangtze River

基　　金：国家自然科学基金项目(41506103)。

摘　　要：长江口为多级分汊型中等潮汐河口,北港是长江口二级入海汊道,被规划为长江口重要通航水道,对其悬沙输运过程和规律的研究至关重要。根据大潮期间北港主槽横断面上均匀分布的5个站点的同步水沙观测资料,采用准调和分析等方法将观测数据分解为潮平均量和多个随潮波动量,以分析北港悬沙输运的横断面空间结构特征和各动力因子的贡献机制。研究结果表明:大潮期间北港主槽横断面总输沙量主要由余流输沙、半日潮流输沙和M4潮流输沙构成,各部分输沙量空间结构差异显著。总输沙量在断面北侧大部分区域指向外海,南侧小部分区域指向上游。强径流作用下的海向余流输沙是构成北侧海向输沙的主要因子。在径流及微弯河势影响下,北侧河道断面落潮流输沙显著强于涨潮流输沙,致使北侧半日潮流输沙指向外海,其贡献机制仅次于余流输沙。南侧河道断面陆向输沙主要由半日潮流输沙和M4潮流输沙组成,其中半日潮流输沙占主要部分。北港水下地貌结构和冲淤演变趋势与断面悬沙分布特征和输运结构密切相关。The Yangtze Estuary is multi-braided river mouth with medium tide characteristics.As a second-grade channel to the sea in Yangtze Estuary,the north channel is planned as an important navigation channel,so the study on its sediment transport law and process has significant meanings.To examine the spatial structure of suspended sediment transport and the contribution mechanism of each driven factor in the north channel,the observation data of tidal current and sediment concentration over five points during spring tide in a cross-section of the channel were decomposed into mean components and several tidal fluctuations based on harmonic analysis.The research results showed that the sediment transport in the study cross section was mainly contributed by residual transport,semi-diurnal tidal transport and M4 tidal transport,and each of them significantly varied over the cross section.The total transport is directed to the outer sea in most section,while only a small part of the southern section showed an upstream transport.The seaward transport in the northern section was mainly driven by the strong discharge induced residual flow.The M2tidal transport in the northern concave bank was significantly stronger during ebb period than that during flood period under the influence of runoff and slightly channel curvature,resulting in a seaward M2tidal transport in the northern transect,which is an major contribution factor only less than the residual transport.The transport in the southern cross section was mainly contributed by M2 tidal transport and M4 tidal transport,in which the former component dominated.The cross-sectional characteristics of sediment concentration and the structural of sediment discharge are closely related to the underwater landform structure and the evolution trend of erosion and deposition in the north channel.

关 键 词：悬沙输运 半日潮流输沙 余流输沙 M4潮流输沙 空间结构特征 准调和分析 北港 长江口 

分 类 号：TV148.1[水利工程—水力学及河流动力学]