Complicated responses of beach erosion and restoration to consecutive typhoons along northeastern Hainan Island, China

Beach landforms show a complicated erosion and recovery process under impacts of consecutive typhoons. In order to study the erosion and accretion response of beaches to two typhoons, representative beach profiles in the Mulan-Baohu Bay, northeastern Hainan Island, were observed and measured before and after two consecutive typhoons, Rammasun and Kalmaegi in 2014. In addition, surficial sediments in each transect backshore were collected to study their depositional environment change. The results show that the former super typhoon Rammasun led to severe beach erosion and sediment transport, which mainly revealed longshore change differences in the Mulan Bay and cross-shore change similarities in the Baohu Bay. And the latter typhoon Kalmaegi caused beach accretion and recovery, which was more obvious in Mulan Bay than in Baohu Bay. After Kalmaegi, the backshore sediments in the Mulan Bay trended to recover to the state before two typhoons and in Baohu Bay showed a greater difference before typhoons. The underwater coral reefs in Baohu Bay restrained beach erosion and accretion from typhoons. Different combinations of typhoon wind directions vs. beach orientations can also cause different beach response to consecutive typhoons. This study will contribute to a better understanding of the complicated responses of different beaches to consecutive typhoons.