Author(s): Ao Chu; Z. B. Wang; H. J. De Vriend; Jiaai Tai
Linked Author(s): Huib J. de Vriend, Zheng Bing Wang
Keywords: Process-based model; Sediment transport; Estuary dynamics; Mouth bar; Yangtze Estuary
Abstract: A hydrodynamic and sediment transport model for the Yangtze Estuary was set up by using the Delft3D modeling system in order to examine and isolate the physical processes responsible for sediment transport and morphological changes around the mouth bar of the estuary. Various combinations of physical processes/mechanisms are turned on in simulations for the sediment transport around the mouth bar area. The influences of river discharge, tidal asymmetry, gravitational circulation and flocculation of fine cohesive sediment on sediment transport are studied. Results show that the spatially and temporally varying balance of physical processes governs the sediment transport at the mouth bar area. In the absence of salinity gradients, runoff induces a large sediment export from the river to the sea. Including gravitational circulation, 3D salinity structure, reduces the net sediment export and results in sediment trapped around the mouth bar. If the flocculation mechanism is included, the deposition of sediment in the mouth bar area will be enhanced. The conclusion is that the gravitational circulation is the prerequisite for mouth bar formation in the Yangtze Estuary.
Year: 2013