Estuary and Coastal Research

Temporal and spatial characteristics of residual currents and net fluxes in the eastern waters of Macao during the summer

  • Fenghua YU ,
  • Shenguang FANG ,
  • Yong HE ,
  • Qing HE
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  • 1. Pearl River Hydraulic Research Institute, Pearl River Water Resources Commission, Guangzhou 510611, China
    2. Key Laboratory of the Pearl River Estuary Regulation and Protection of Ministry of Water Resources, Guangzhou 510611, China
    3. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China

Received date: 2022-05-16

  Accepted date: 2022-10-20

  Online published: 2023-05-25

Abstract

This study analyzed the spatial and temporal variations of depth-averaged residual currents of Eulerian, Lagrangian, and Stokes during a tidal cycle in the eastern waters of Macao. Data were collected for 15 days during the summer from two field stations using a method specifically designed to deal with stratified residual flow. Our findings revealed similar dynamical characteristics during flood and ebb tides in the southeast and northeast waters of Macao, with currents being more pow-erful in the southeast. We found that the material carried by the tidal current tends to travel northwest at the station A6 and southeast at A7, with Lagrange residuals being around 2.2 cm/s and 5.1 cm/s, respectively, which is slightly smaller than Eulerian residuals. Influenced by the southwest monsoon, the directions of Euler, Lagrangian, and Stokes surface residual currents on the surface generally pointed northeast. Furthermore, our results showed that the depth-averaged residuals during a tidal cycle pointed towards the open sea during upstream flooding, towards nearshore in northeast waters, and towards the east in southeast waters under non-flooding conditions. The intensity of Stokes drift in southeast waters was primarily influenced by wind on the water surface, while the effect of wind on the northeast waters was limited and weakened by enhanced runoff. The intensity and direction of transportation in both southeast and northeast waters were related to wind speeds on the sea surface. During summer, analysis of net tidal flux indicated a relatively stable counterclockwise residual current circulation in the waters downstream to the outlet of the Macao waterway. This circulation was driven by the strong northeast littoral current outside the Pearl River Estuary, leading to the formation of an east-west flowing structure compensated in the east waters of Macao. During this season, part of the tidal sediment was intercepted by this unique dynamic structure discharged by east four mouths in the Lingdingyang Estuary upstream and re-entered the Macao waters with rising tidal water, which leaded to sedimentation of beaches and troughs and poor water exchange.

Cite this article

Fenghua YU , Shenguang FANG , Yong HE , Qing HE . Temporal and spatial characteristics of residual currents and net fluxes in the eastern waters of Macao during the summer[J]. Journal of East China Normal University(Natural Science), 2023 , 2023(3) : 147 -157 . DOI: 10.3969/j.issn.1000-5641.2023.03.014

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