Emerging signals of coastal system changes under rapid anthropogenic disturbance in Hangzhou Bay, China

Coastal systems are continuously reshaped by rapid anthropogenic disturbance globally. However, the awareness of how coastal systems adapt to rapid anthropogenic disturbance remains inadequate. Thus, this study assessed the spatial response of coastal systems to rapid anthropogenic disturbances, and a typical coastal system (Hangzhou Bay) was selected for a case study. Three environmental indicators (i.e., coastline change rate, accretion/erosion grade, and the displacement of the center of gravity) were selected to measure the morphological changes in the coastal system between 1990 and 2020. The results showed that the coastal waters of Hangzhou Bay decreased by 432 km2, and the coastal morphology became structured driven by increasing artificial coastlines. Moreover, the accretion-erosion equilibrium of underwater elevation transitioned northwest, which derived the shift of geometric center of gravity toward the northwestern part of the coast. These fluctuating signals provided us with a macroscopic perception of coastal system changes, which is expected to provide local decision-makers with sites where coastal systems are adaption loss to assist coastal protection.