长江口浑浊带核心区北槽水动力特征研究
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摘要
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。
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.
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.
引文
[1] 沈焕庭, 潘定安. 长江河口最大浑浊带[M]. 北京: 海洋出版社, 2001: 39-40. Shen Huanting, Pan Dingan. Turbidity Maximum in the Changjiang Estuary[M]. Beijing: China Ocean Press, 2001: 39-40.
[2] Glangeaud L. Transport et sedimentation clans1’estuairc et a l’embouchure de La Gironde[J]. Bulletin of Geological Society of France, 1938, 8: 599-630.
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[8] Jiang Chenjuan, de Swart H E, Li Jiufa, et al. Mechanisms of along-channel sediment transport in the North Passage of the Yangtze Estuary and their response to large-scale interventions[J]. Ocean Dynamics, 2013, 63(2/3): 283-305.
[9] Li Xiangyu, Zhu Jianrong, Yuan Rui, et al. Sediment trapping in the Changjiang Estuary: observations in the North Passage over a spring-neap tidal cycle[J]. Estuarine, Coastal and Shelf Science, 2016, 177: 8-19.
[10] Liu Gaofeng, Zhu Jianrong, Wang Yuanye, et al. Tripod measured residual currents and sediment flux: impacts on the silting of the Deepwater Navigation Channel in the Changjiang Estuary[J]. Estuarine, Coastal and Shelf Science, 2011, 93(3): 192-201.
[11] Song Dehai, Wang Xiaohua, Cao Zhenyi, et al. Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 1. Observations over spring and neap tidal cycles[J]. Journal of Geophysical Research: Oceans, 2013, 118(10): 5555-5567.
[12] 沈焕庭, 吴加学, 刘新成, 等. 长江河口物质通量[M]. 北京: 海洋出版社, 2001: 11-153. Shen Huanting, Wu Jiaxue, Liu Xincheng, et al. Material Flux of the Changjiang Estuary[M]. Beijing: China Ocean Press, 2001: 11-153.
[13] Scully M E, Geyer W R, Lerczak J A. The influence of lateral advection on the residual estuarine circulation: a numerical modeling study of the Hudson River Estuary[J]. Journal of Physical Oceanography, 2009, 39(1): 107-124.
[14] Nunes R A, Simpson J H. Axial convergence in a well-mixed estuary[J]. Estuarine, Coastal and Shelf Science, 1985, 20(5): 637-649.
[15] Huzzey L M, Brubaker J M. The formation of longitudinal fronts in a coastal plain estuary[J]. Journal of Geophysical Research, 1988, 93(C2): 1329-1334.
[16] Cheng Peng, Wilson R E, Chant R J, et al. Modeling influence of stratification on lateral circulation in a stratified estuary[J]. Journal of Physical Oceanography, 2009, 39(9): 2324-2337.
[17] Lerczak J A, Geyer W R. Modeling the lateral circulation in straight, stratified estuaries[J]. Journal of Physical Oceanography, 2004, 34(6): 1410-1428.
[18] 汪亚平, 高抒, 贾建军. 海底边界层水流结构及底移质搬运研究进展[J]. 海洋地质与第四纪地质, 2000, 20(3): 101-106. Wang Yaping, Gao Shu, Jia Jianjun. Flow structure in the marine boundary layer and bedload transport: a review[J]. Marine Geology & Quaternary Geology, 2000, 20(3): 101-106.
[19] 李文祥, 张静怡, 徐小明. 长江口潮流速垂线分布规律研究[J]. 水文, 2010, 30(3): 68-70, 76. Li Wenxiang, Zhang Jingyi, Xu Xiaoming. Study on vertical distribution of Yangtze Estuary tidal velocity[J]. Journal of China Hydrology, 2010, 30(3): 68-70, 76.
[20] van Rijn L C. Principles of sediment transport in rivers, estuaries and coastal seas, Part Ⅰ: Edition 1993[M]. The Netherlands: Aqua Publications, 1993.
[2] Glangeaud L. Transport et sedimentation clans1’estuairc et a l’embouchure de La Gironde[J]. Bulletin of Geological Society of France, 1938, 8: 599-630.
[3] Festa J F, Hansen D V. Turbidity maxima in partially mixed estuaries: a two-dimensional numerical model[J]. Estuarine and Coastal Marine Science, 1978, 7(4): 347-359.
[4] Allen G P, Salomon J C, Bassoullet P, et al. Effects of tides on mixing and suspended sediment transport in macrotidal estuaries[J]. Sedimentary Geology, 1980, 26(1/3): 69-90.
[5] 沈焕庭, 郭成涛, 朱慧芳, 等. 长江河口最大浑浊带的变化规律及成因探讨[M]. 北京: 科学出版社, 1984: 76-89. Shen Huanting, Guo Chengtao, Zhu Huifang, et al. Discussion on Variations and Formation of the Turbidity Maximum in the Changjiang Estuary[M]. Beijing: Science Press, 1984: 76-89.
[6] 田向平. 珠江河口伶仃洋最大混浊带研究[J]. 热带海洋, 1986, 5(2): 27-35. Tian Xiangping. A study on turbidity maximum in Lingdingyang Estuary of the Pearl River[J]. Tropical Oceanography, 1986, 5(2): 27-35.
[7] 时钟, 陈伟民. 长江口北槽最大浑浊带泥沙过程[J]. 泥沙研究, 2000(1): 28-39. Shi Zhong, Chen Weiming. Fine sediment transport in turbidity maximum at the North Passage of the Changjiang Estuary[J]. Journal of Sediment Research, 2000(1): 28-39.
[8] Jiang Chenjuan, de Swart H E, Li Jiufa, et al. Mechanisms of along-channel sediment transport in the North Passage of the Yangtze Estuary and their response to large-scale interventions[J]. Ocean Dynamics, 2013, 63(2/3): 283-305.
[9] Li Xiangyu, Zhu Jianrong, Yuan Rui, et al. Sediment trapping in the Changjiang Estuary: observations in the North Passage over a spring-neap tidal cycle[J]. Estuarine, Coastal and Shelf Science, 2016, 177: 8-19.
[10] Liu Gaofeng, Zhu Jianrong, Wang Yuanye, et al. Tripod measured residual currents and sediment flux: impacts on the silting of the Deepwater Navigation Channel in the Changjiang Estuary[J]. Estuarine, Coastal and Shelf Science, 2011, 93(3): 192-201.
[11] Song Dehai, Wang Xiaohua, Cao Zhenyi, et al. Suspended sediment transport in the Deepwater Navigation Channel, Yangtze River Estuary, China, in the dry season 2009: 1. Observations over spring and neap tidal cycles[J]. Journal of Geophysical Research: Oceans, 2013, 118(10): 5555-5567.
[12] 沈焕庭, 吴加学, 刘新成, 等. 长江河口物质通量[M]. 北京: 海洋出版社, 2001: 11-153. Shen Huanting, Wu Jiaxue, Liu Xincheng, et al. Material Flux of the Changjiang Estuary[M]. Beijing: China Ocean Press, 2001: 11-153.
[13] Scully M E, Geyer W R, Lerczak J A. The influence of lateral advection on the residual estuarine circulation: a numerical modeling study of the Hudson River Estuary[J]. Journal of Physical Oceanography, 2009, 39(1): 107-124.
[14] Nunes R A, Simpson J H. Axial convergence in a well-mixed estuary[J]. Estuarine, Coastal and Shelf Science, 1985, 20(5): 637-649.
[15] Huzzey L M, Brubaker J M. The formation of longitudinal fronts in a coastal plain estuary[J]. Journal of Geophysical Research, 1988, 93(C2): 1329-1334.
[16] Cheng Peng, Wilson R E, Chant R J, et al. Modeling influence of stratification on lateral circulation in a stratified estuary[J]. Journal of Physical Oceanography, 2009, 39(9): 2324-2337.
[17] Lerczak J A, Geyer W R. Modeling the lateral circulation in straight, stratified estuaries[J]. Journal of Physical Oceanography, 2004, 34(6): 1410-1428.
[18] 汪亚平, 高抒, 贾建军. 海底边界层水流结构及底移质搬运研究进展[J]. 海洋地质与第四纪地质, 2000, 20(3): 101-106. Wang Yaping, Gao Shu, Jia Jianjun. Flow structure in the marine boundary layer and bedload transport: a review[J]. Marine Geology & Quaternary Geology, 2000, 20(3): 101-106.
[19] 李文祥, 张静怡, 徐小明. 长江口潮流速垂线分布规律研究[J]. 水文, 2010, 30(3): 68-70, 76. Li Wenxiang, Zhang Jingyi, Xu Xiaoming. Study on vertical distribution of Yangtze Estuary tidal velocity[J]. Journal of China Hydrology, 2010, 30(3): 68-70, 76.
[20] van Rijn L C. Principles of sediment transport in rivers, estuaries and coastal seas, Part Ⅰ: Edition 1993[M]. The Netherlands: Aqua Publications, 1993.