Dynamic Geomorphology Linkage Mechanism of Pearl River Estuary Under Strong Human Activities

The dynamic geomorphic system of the Pearl River estuary in China has remained basically stable in the past century. The trend of seabed evolution is characterized by “stability”, “slight variability”, and “plasticity”. In the past decade, human activities, such as beach reclamation, bridge construction across the sea, and large-scale sand mining have taken place in the Pearl River estuary, which has destroyed the original “three beaches and two troughs” landform pattern of the Pearl River estuary. In many human activities, large-scale sand pits have destroyed the geomorphic pattern of the estuary, and the dynamic balance system that maintains the stability of the estuary’s geomorphic pattern has been broken. Based on the measured basic data, this study analyzes the hydrodynamic, sediment, and riverbed evolution characteristics after the formation of the sand pit. A two-dimensional flow and sediment transport mathematical model is established for the Pearl River Delta river network and estuarine waters to simulate the temporal and spatial changes of estuarine shelf water, flushing water, and sediment transport. Through the medium and long period dynamic geomorphic evolution model, the long-term geomorphic evolution trend of estuary under the new pattern is simulated, and the response and adaptation process of dynamic system and geomorphic pattern are predicted. The research results show that the influence of large-scale sand pits on hydrodynamic forces has spread to the upstream of the Pearl River estuary, and the original geomorphic pattern will be difficult to maintain and develop. This study will provide the scientific basis for the safety of flood control, navigation and water supply in the estuary of Pearl River, and provide the technical support for the maintenance of the Hong Kong–Zhuhai–Macau Bridge project.