Estuarine Circulation Patterns in a Complex Geometry Estuary: Dinh An Estuary, Mekong River
Estuarine Circulation Patterns in a Complex Geometry Estuary: Dinh An Estuary, Mekong River
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DOI：
10.1007/s40710-018-0308-5
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发表时间：
2018-05
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影响因子：
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通讯作者：
N. Nguyen;S. Nakajo;T. Mukunoki;G. Tsujimoto
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文献类型：
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作者：
N. Nguyen;S. Nakajo;T. Mukunoki;G. Tsujimoto
河口环流是一种自然现象，影响着世界范围内河口的演变。本文以湄公河定安河口为例，探讨了复杂断面河口的EC模式。在2009年9月15日至30日期间，声学多普勒水流剖面仪（ADCP）在河口附近的样带测量了一系列河流流量和水流剖面。用水准杆同时记录了潮汐高程和河流流量。观测数据表明，在高流量季节（5 ~ 10月），河流量期比潮汐期滞后6 h。在退潮逆转期间，河流流量在−5000 ~ 13600 m3/s范围内，观测到4种主要类型的EC。在−6000 ~ 5000 m3/s的流量范围内，有两种主要的涨潮模式。典型的EC型（海水在河床附近向陆地流动，河水在地表附近向海洋流动）只出现在退潮时最深的河道中，这是由于盐水入侵引起的密度不平衡。结果表明，潮相和河床几何形状对河口EC型的形成起重要作用。本文为深入研究含盐入侵、环境过程、泥沙动力和河口形态提供了必要的信息。
Estuarine circulation (EC) is a natural phenomenon that contributes to the evolution of estuaries worldwide. This paper uses the Dinh An estuary, Mekong River as a case study to investigate patterns of EC in a complex cross-section estuary. An Acoustic Doppler Current Profiler (ADCP) measured a series of river discharge and current profiles at a transect near the mouth of the estuary between 15 and 30 September 2009. Tidal elevation was also recorded concurrently with the river discharge by using a leveling rod. The observed data reveal that the river-discharge phase lagged 6 h behind the tidal phase in the high-flow season (May to October). Four main types of EC were observed during the reversal time in the ebb tide with river discharges in a range of −5000 m3/s to 13,600 m3/s. There were two main flood tide patterns, which corresponded to the discharges from −6000 m3/s to 5000 m3/s. The classical EC type (seawater flows landward near the bed and river water flows seaward near the surface) appeared only in the deepest channel in the ebb tide as saline intrusion induced a density imbalance. The results suggest that tidal phase and bed geometry play important roles in forming EC patterns in estuaries. This paper provides essential information related to flow structure in complex bathymetry estuaries for further studies on saline intrusion, environmental processes, sediment dynamic and estuarine morphology.