Research on Nansan Islands Beach Response to Strong Typhoon Mangkhut

The spatiotemporal dynamics of the beach under extreme wave conditions is essential for beach erosion mechanism. The mechanism is helpful to coastal engineering management, resource utilization, disaster prevention, and mitigation. Before and after the landfall of strong Typhoon Mangkhut, the beach profile survey and beach surface sediment sampling were carried out at the beach of Nansan Island, Zhanjiang, China. By comparing the beach profile changes and sediment dynamic characteristics before and after the landfall of Mangkhut, we got the following results: (1) Nansan Island Beach responded to extreme dynamic conditions rapidly. During the whole response-recovery stage, sediments in the supratidal zone and the sand bars in the subtidal zone interact with each other. The intertidal zone is relatively stable without noticeable erosion/accretion changes. (2) Influenced by Typhoon Mangkhut, surface sediments on the beach became finer and better sorted. In the recovery stage, sediments were redistributed along the beach surface. (3) The recovery process of the supratidal zone was relatively independent. In the process of recovery, sediments on the beach surface were redistributed during transporting through the intertidal zone, which affected the recovery rate of the subtidal zone.