Morphological Evolution of the Lingding Channel in the Pearl River Estuary over the Last Decades

Dominated by the combined influence of fluvial and marine processes as well as human activities, estuarine regions are facing serious challenges, especially Lingding Bay in the Pearl River Estuary (PRE). The Lingding Channel is the main estuarine channel in Lingding Bay, and it connects to the outer sea, so its morphological evolution is very critical for navigation and estuarine management. Underwater topography data and remote sensing images of Lingding Bay in the PRE were employed to examine the morphological evolution of the Lingding Channel over the last decades (1965-2016). The results show that the West Shoal in Lingding Bay has extended eastward through a silting process caused by land reclamation and sediment discharge from the Pearl River; consequently, the Lingding Channel has become narrow. Additionally, the Lingding Channel has become deep because of channel regulation activities. In the last 10 years, large-scale sand-dredging activities at the Fanshi Shoal have deepened the shallow shoal near Lingding Channel, and many large and deep holes have formed with irregular shapes. In summary, drastic changes have occurred in the landforms near the Lingding Channel, which will likely influence the future stability of the channel. This represents a new and concerning challenge. Furthermore, sand-dredging activities could also produce large amounts of turbid water that could be transported into the Lingding Channel and increase the siltation rate.