Cumulative response of estuarine bay hydrodynamic environment to human activities: example of Lingding Bay of the Pearl River Estuary

Abundant tidal flat resources exist along the coast zone of the Lingding Bay of the Pearl River Estuary,reclamation of which can ease the contradiction between land resource shortage and demand for social and economic development. The shoreline at the Lingding Bay changed significantly since 1981 due to reclamation of tidal flats. However,there is still a lack of understanding on the cumulative response process of estuarine hydrodynamic environment to reclamation of tidal flats. In this study,eight cases were selected as representative reclamation stages in the Lingding Bay since 1981,a two-dimensional tidal wave mathematical and tidal current mathematical model were developed to analyze the cumulative changing process of tidal volume,constituent tidal amplitude,as well as tidal current velocity. The results show that tidal volume decrease for bay mouth section,Neilingding section,Shenzhen Bay section,as well as Nansha section compared to their conditions in 1981 are about 4.9%-6.0%,9.0%-12.8%,17.8%,and 5%-6.3%,respectively. The M₂ constituent tide amplitude in the Lingding Bay in 2018 increases from south to north,and from west to east,which means tidal wave intensifies from south to north in the bay,compared to its condition in 1981. Tidal range change tendency in the Lingding Bay consistent with that of M₂ constituent tidal amplitude,while the tidal characteristics in the bay does not changed,the tidal current velocity of the bay decrease generally,with more decrease on the west bank of the bay more than that on the east bank,while the current velocity near the bay top increases slightly,after the aforementioned reclamation stages were performed. The results of this study can inform the protection and utilization of tidal flat resources,protection of coastal engineering,coastal disaster prevention and mitigation on the Lingding Bay of the Pearl River Estuary and similar estuarine bays,as well provide a scientific basis for comprehensive tidal flat utilization and protection.