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Wave-Current Actions on the Transport of Sediment in Deep Bay, Hong Kong

Author(s): Yong Chen; Onyx Wing Hong Wai

Linked Author(s): Onyx W.H. Wai

Keywords: Cohesive sediment; Intertidal flat; Waves; Deep Bay; Finite element method; Sediment transport

Abstract: Deep Bay has a relatively shallow flow depth and wave actions play an important role in the fate and transport of sediment in the shallow bay. A 3-dimensional (3D) split-operator finite element model has been applied to simulate the wave-current induced transport of cohesive sediment in Deep Bay. The wave climate is calculated by the conservation of wave action equation and the eikonal equation that take into account of wave refraction-diffraction and time varying non-uniform currents. The wind action has also been incorporated in the wave climate calculation. The wave model is directly coupled with a tidal flow model through a wave-current bottom boundary layer model and vertical eddy viscosity coefficients. The model was calibrated and verified against a set of 16-hour field measurements including water elevations, flow velocities, suspended sediment concentration, wind conditions, and swell properties collected in 1986 during a spring tidal period and a neap tidal period. The calibrated/validated model was then applied to simulate the sediment transport process in Deep Bay with the present coastline and bathymetry. Wind is found to be an important factor in modifying the wave propagation pattern in the bay. It is also found that the suspended sediment concentration can increase by 20 times if wave actions are in comparable magnitude with the current flow. The computed results are useful for shore and environmental protection and coastal project management in the bay.


Year: 2005

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