Physical model study for effects of the Hong Kong–Zhuhai–Macao Bridge on harbors and channels in Lingdingyang Bay of the Pearl River Estuary

Abstract

Human activities, involving construction such as large-scale bridge projects in tidal estuaries, can lead to undesirable and severe morphodynamic responses, such as excessive siltation in the harbors and channels. Lingdingyang Bay of the Pearl River Estuary (LBPRE) is a typical bay with unique geomorphological features that might cause complex changes in hydrodynamic features and sediment movement. The LBPRE includes a number of harbors and channels, including Nansha Harbor of Guangzhou Port and the western harbors of Shenzhen Port, which are two hub ports in South China, and their corresponding and important Lingding and Tonggu channels. Designed to cross over the LBPRE to connect Hong Kong, Zhuhai, and Macao, the proposal of the Hong Kong–Zhuhai–Macao Bridge (HZMB) is a representative of the most complicated and the longest sea-crossing transportation project in the world, which consists of several segments of bridge, a tunnel, and two man-made islands. Therefore, it is of extreme significance to demonstrate the effects of the HZMB on the relevant harbors and channels through study. In this article, a large-scale physical model of tidal currents and sediment movement, covering the entire LBPRE with a horizontal scale of 1:900 and a vertical scale of 1:120, was presented with emphasis on the effects of the HZMB on water flow and sediment movement. The design and layout of the model are described in detail. The accuracy of the model was verified with in situ data; the results show that the simulated tidal levels, currents, and deposition in the channels are all in good agreement with measured field data. Then, evaluation on the effects of the HZMB was carried out by comparing the scenarios with and without the bridge; the effects on hydrodynamics of the LBPRE and the erosion and deposition occurring in the harbors and channels were analyzed. The following main conclusions were reached. (1) The effects of the HZMB on tidal levels, currents, and prisms were all relatively small, and the influence was limited within an area of 5 km upstream and downstream from the bridge. The construction of the HZMB tends to lead to increase of the tidal currents in Lingding Channel between the two man-made islands, which is favorable for maintenance of water depth in the channel. (2) The effects of the HZMB on erosion and deposition in the harbors and channels are insignificant. (3) The construction of the HZMB is not predicted to have substantial effects on changing the pattern of the shoals and channels in the LBPRE. (4) The HZMB is feasible as far as its effects on hydrodynamics, harbors, and channels are concerned.