3D numerical study on cohesive sediment dynamics of the Pearl River Estuary in the wet season

Abstract

Abstract: The cohesive sediment dynamics have great potential engineering and environmental impacts in the Pearl River Estuary (PRE). In this study, we established a 3D unstructured triangular grid hydrodynamics model by using the SELFE (Semi-implicit Eulerian-Lagrangian Finite Element) model for the PRE, considering the baroclinic current, tidal current and wind current. On the basis of the hydrodynamics model, we then developed a cohesive sediment model including a bed change module. From the numerical results which are in good agreement with the field data obtained in the wet season, the characteristics of turbidity maximum (TM) in the PRE can be well reproduced, and the relevant sediment dynamics can be explained. The results show that the suspended sediment concentration (SSC) in the west side is higher during the wet season, which indicates that the suspended sediment in the PRE is terrigenous. The TM is found in all “three shoals”, and the suspended sediment concentration is up to 0.5 g/L. The tidal dynamics, gravitational circulation and sediment resuspension and deposition processes are the primary formation mechanisms of TM in the PRE. TM in the middle shoal is mainly caused by the sediment resuspension and deposition processes, on the other hand, the gravitational circulation is the predominant formation mechanisms of TM in the west shoal.

Key words: Pearl River Estuary, sediment dynamics, turbidity maximum, three-dimensional model

CLC Number:

TV148

ZHU Ze-nan, WANG Hui-qun, GUAN Wei-bing, CAO Zhen-yi. 3D numerical study on cohesive sediment dynamics of the Pearl River Estuary in the wet season[J]. Journal of Marine Sciences, 2013, 31(3): 25-35.

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