Flow prediction using ENVISAT RA-2 sea surface height validated model: A case study for the effect of Hong Kong-Zhuhai-Macau Bridge in the Pearl River Estuary, China

The Delft3D-Flow hydrodynamic model was used to predict the impact of the Hong Kong-Zhuhai-Macau Bridge on the tidal flow in the Pearl River Estuary. In addition, the impacts of the flow currents on nearby bridge piers and artificial islands were assessed. To obtain additional spatial and temporal observations relative to the tidal gauge station observations, the sea surface height, which was derived from satellite altimetry ENVISAT RA-2, was closely correlated with the simulated tidal levels on individual days. These variables were modeled in the presence and absence of the Bridge, and the sea surface height validated numerical model was used to study the impacts of the Bridge on local water levels and circulation patterns. The construction of this Bridge resulted in small changes in tidal levels in that area. The average highest and lowest tidal levels changed by less than 0.01 m, which is about 0.4% of the highest tidal level and 2% of the lowest tidal level. The total tidal range changed by nearly 0.015 m. These results indicated that coastal engineering hardly affects the tidal flow in the Pearl River Estuary. In addition, complex eddy and circulation patterns were discovered near artificial islands. It is important to understand the complex flow patterns to ensure traffic safety during bridge construction and to determine the associated impacts of the bridge on tidal currents in the Estuary.