ABSTRACT

Xiamen Bay has relied on reclamation as source of land supply for urban development since the 1960s. A new airport is proposed to be constructed by dredging and reclamation around 140.29 km2 over an intertidal flat of Xiamen Bay. This study focuses on the hydrodynamic induced by the reclamation and suspended sediment transport process due to dredging over the intertidal flat, where the tidal current due to local force tide rather than small wave is the dominant dynamic for sediment transport and morphology. A two-dimensional numerical model discretized by a cell-centered finite volume method is developed with high resolution to study the possible impact of dredging and reclamation in Xiamen Bay. The current significantly decreases larger than 0.08 m/s at the both entrances of the narrowed channel between the Daden Island and the Xiaodeng Island, but decreases during flood tide and increases during ebb tide just in the narrowed channel. The tidal flux has a remarkable increase more than 13% during flood tide but a small increase less than 3.5% during ebb tide, which directly results in the weakness of net tidal flux in ebb direction. The five channels in the bay have an essential influence to sediment transport, and the suspended sediment is driven by the reciprocating current along the channels. Most of dredging suspension would be transported into the inner bay via the northern channel of the Kinmen Island, but transported outside via the western channel of the Kinmen Island. The five channels working as a dredge pump result in the far-field effect of dredging sediment for the long transport distance. This characteristic leads to a banding distribution of suspended sediment around the Kinmen Island. The other part of dredging sediment would move around the reclamation. The selection of dredging time and intensity has an important contribution for management of vicinal water environment.

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