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ZHANG Xiaohe,LI Jiufa,ZHU Wenwu,CHENG Heqin,CHEN Wei. 2015. The self-regulation process and its mechanism of channels’ bed changes in the Changjiang (Yangtze) Estuary in China. Acta Oceanologica Sinica, 34(7):123-130
The self-regulation process and its mechanism of channels’ bed changes in the Changjiang (Yangtze) Estuary in China
近期长江河口冲淤演变过程及自动调整机理研究
Received:October 27, 2014  Revised:January 07, 2015
DOI:10.1007/s13131-015-0699-3
Key words:Changjiang Estuary  bathymetric changes  self-regulation  human activities  tidal current  sediment transport
中文关键词:  长江河口  河床演变  自动调整  人类活动  潮流  泥沙运动
基金项目:
Author NameAffiliationE-mail
ZHANG Xiaohe State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China  
LI Jiufa State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China jfli@re.ecnu.edu.cn 
ZHU Wenwu State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China  
CHENG Heqin State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China  
CHEN Wei Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht 3584 CC, the Netherlands  
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Abstract:
      Recent bathymetric changes in the Changjiang Estuary under the influence of artificial regulation engineerings and basin reservoirs have been analyzed based on the maritime charts since 1997 and recent fieldworks. The results indicate a slight erosion of the channels in the upper and middle estuary, continuing deposition and seaward move of the mouth bar crest and intensifying erosion at the nearshore seabed. It is noteworthy that the morphological evolution caused by intensive human activities dominates over the changes from nature process. First, the riverbes are eroded overall in the South Branch (SB), the South Channel (SC) and the upper and middle reaches of the North Channel (NC). The nearshore seabed outside the river mouth is being eroded slightly, which is attributed to the declining sediment supply from the Changjiang Basin due to the construction of the Three Gorges Dam upstream. The sediment above the seabed is very active and coarsened, meanwhile, sand waves are becoming more distinct. Second, a deposition occurs in the North Brach (NB), the mouth of the NC, the mouth bars of the North Passage (NP) and the South Passage (SP) and especially the main channel of the NP, where it shows a massive siltation after the deep waterway project. The reasons for the recent changes are not only the dynamic structure in estuarine mouth bars, but also the supply of sediment resuspension in a local and offshore area. Meanwhile, the severe erosion and siltation in some reaches is related to the construction of estuarine engineerings. It is indicated that the Changjiang Estuary is gradually self-adjusted and adapting to the varying natural factors and intensive human activities. The study on the mechanism of self-regulation of the recent bathymetric changes in the Changjiang Estuary has important and practical significance.
中文摘要:
      基于长江河口1997年以来数字地形图和近期水文泥沙实测资料, 分析研究了近期长江河口大量人工整治工程和流域水库工程建造的影响下的河口河道自动调整过程。结果表明:1997年以来的16年中河口段中上游河道微冲刷、拦门沙滩顶仍保持淤积外移、口门外侧近海域冲刷的态势略有增强, 而其影响原因与历史时期的自然因素影响为主略有差异, 近期人类高强度活动的影响贡献率增大。首先, 南支至南港和北港中上游河段河床发生普遍冲刷, 河床沙活动较活跃, 床面微地貌沙波发育更明显, 而口门外侧海域地形略有冲刷蚀退, 这些变化与流域来沙锐减有直接关系;北支、北港口门、南槽和北槽河道拦门沙河段呈淤积, 尤其北槽主航道的拦门沙河段6m水深浚深为12.5m后回淤量很大, 这些与拦门沙河道动力结构环境、河口和海域再悬浮泥沙补给有关;局部河段出现强冲和强淤现象, 与近期河口工程建造有关。所以, 长江河口近期正处在对自然因素变化和人类活动增强的自我缓慢地自动调整和适应过程之中。故然, 开展此类研究有其重要的现实意义。
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