华东师范大学学报（自然科学版） ›› 2020, Vol. 2020 ›› Issue (3): 1-12.doi: 10.3969/j.issn.1000-5641.201941015

• 河口海岸学 • 上一篇    下一篇

潮控型分汊河口分流过程探讨——以长江北支口为例

陆佳玉, 葛建忠, 丁平兴   

  1. 华东师范大学 河口海岸学国家重点实验室, 上海 200241
  • 收稿日期:2019-05-10 发布日期:2020-05-22
  • 通讯作者: 丁平兴,男,教授,博士生导师,研究方向为物理海洋学.E-mail:pxding@sklec.ecnu.edu.cn E-mail:pxding@sklec.ecnu.edu.cn
  • 基金资助:
    国家重点研发计划（2016YFA0600903）；中美大河三角洲侵蚀灾害与应对策略比较研究（2017YFE0107400）；国家自然科学基金（41776104）

A discussion on the diversion process of tide-dominated estuary bifurcation: The North Branch estuary of the Yangtze River

LU Jiayu, GE Jianzhong, DING Pingxing   

  1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
  • Received:2019-05-10 Published:2020-05-22

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摘要： 长江北支口是典型的潮控型分汊河口，其水动力及其汊道分流过程是影响潮控河口物质输运和地貌演变的主要因素. 本文基于2018年春季在北支口各汊道的坐底三脚架资料与断面走航资料，计算各汊道的优势流. 结果发现：大潮时，北支三条港与顾圆沙南水道均呈现涨潮优势，水流净向陆输运；顾圆沙北水道则呈现落潮优势，水流净输运方向指向口外. 同时，结合FVCOM高分辨率数值模拟，对北支口分流过程进行模拟. 结果表明，由于顾圆沙南水道近海口断面面积远大于北水道，且方位与涨潮时潮波传播方向一致，大部分外海潮波经过顾圆沙南水道上溯，涨潮量在南北水道空间上分配的差异性极大；同时，一部分经顾圆沙南水道上溯的潮波会越滩至北水道，与上游径流汇合后，共同经顾圆沙北水道下泄，北水道的落潮量增加，落潮量在空间上分配的差异性减小. 当大潮时，顾圆沙北水道的涨落潮分流比为29.7%、47.2%；小潮时，顾圆沙北水道的涨落潮分流比为41.6%、43.1%. 北支口余流基本态势为南水道进、北水道出. 这些指标及分流特征可为河口的物质输运、地貌演变及各汊道的发育、维持和衰亡过程的预测提供关键的指示参数.

关键词: 北支口, 潮控, 分汊, 分流比, FVCOM

Abstract: The North Branch estuary of the Yangtze River is a typical tide-dominated estuary with bifurcation. The hydrodynamics and diversion processes are the major factors in sediment transport and geomorphology evolution of the tide-dominated estuary. This paper is based on data from the bottom tripod system and a cross-section survey of the North Branch in April 2018, whereby the dominant flow of each channel is calculated. The results show that during the spring tide cycle, the Santiao Port and the Guyuansha south waterway are flood-dominated and the net tidal current flows landward, whereas the Guyuansha north waterway is ebb-dominated, and the net flow has a seaward direction. Moreover, a high-resolution numerical FVCOM model is used to simulate the diversion process of the North Branch estuary. The results suggest that: the cross-sectional area of Guyuansha south waterway is much bigger than that of the north waterway, and the propagation direction of the lateral tide is consistent with the orientation of the Guyuansha south waterway, which mainly has onshore movement through the Guyuansha south waterway. The spatial distribution of the flood tide flow is significantly uneven in these two waterways. Meanwhile, tidal current from the Guyuansha south waterway crosses the shallow shoal and reaches the north waterway. It produces a net flow with the seaward direction through the north waterway. The flood-tide and ebb-tide diversion ratio of the Guyuansha north waterway are 29.7% and 47.2%, respectively, during the spring tide period and 41.6% and 43.1%, respectively, during the neap tide period. The residual patterns indicate that the tidal current enters the estuary from the south waterway and exits through the north waterway. These indicators and diversion characteristics can help predict estuarine sediment transport and geomorphological evolution processes within an individual bifurcated channel.

Key words: the North Branch estuary, tide-dominated, bifurcation, flow diversion ratio, FVCOM

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