Long-Term Geomorphic Changes in the Coastal Profile of Lingding Bay in the Pearl River Estuary and the Response to Tides Since 1906

Lingding Bay in the Pearl River Estuary, located on the north coast of the South China Sea, experiences frequent storm surges caused by typhoons. The geomorphic features of the Pearl River Estuary have changed tremendously due to natural processes and human activities over the last century, and these changes have led to changes in the hydrodynamic environment, such as a reduced capacity for holding tides in the coastal zone. In this paper, the relation between geomorphic features and the capacity for holding tides is analyzed. In order to ascertain how historical landform change affects this capacity, we study the spatial morphology change of Lingding Bay in the Pearl River Estuary (since 1906) through the analysis of historical topographic maps and nautical charts. The shape index and fractal dimension were introduced as indicators to reflect coastline changes that have affected the tides. The tidal dissipation rate and tidal influx were found to describe a bay’s capacity to hold tides. The results show that, since 1906, the tidal influx and the tidal dissipation rate have decreased by about 14.11% and 23%, respectively, in the study area. We suppose that these changes could be attributed to geomorphic changes, primarily changes brought about by land reclamation projects.