关键词: 西沙群岛, 珊瑚礁, 岸线演化, 海洋遥感, 全球变化

Abstract: Xisha Islands are located at the centre enroute from Hainan Island to other oceanic islands in the South China Sea (SCS). They are typical geological and geomorphological complexes formed by the coupling interaction between tectonic and biological processes. However, their exposed area is also subjected to a typical climate-vulnerable area in SCS, being severely influenced by extreme marine hazards, e.g., typhoons and storm surges. Coral reef coastal areas are expected to be broadly developed in the future, following the strategy of high-quality development of reef island resources in the Xisha Islands. With the aggravating risks and threats of marine environmental disasters due to global climate change considered, the challenges of marine hazards prevention and mitigation in Xisha Islands are further heightened. Hence, to reveal the geomorphic response of coral reef coasts to marine environments becomes a critical issue that urgently needs to be addressed. So that, the survival prospects of coral reefs under future marine environmental impacts could be fairly evaluated for sustainable maritime management. Therefore, this study employs 18 coral reefs in Xisha Islands as their research subjects, using marine satellite remote sensing data to acquire their coastal geomorphology images in 2015 and 2023. Morphological change of these coral reef coasts is characterized based upon marine geology and coastal geomorphology theories. Their surrounding marine environmental conditions are examined using physical oceanographic analysis methods. This study attempts to link the spatial difference of coastal morphological change among reef islands to environmental conditions. The coupled analysis demonstrates only a weak correlation (R2 between 0.06 and 0.21) the coastal morphological difference of these coral reefs and their regional marine environmental characteristics. Therefore, this work suggests that to scientifically asses the survival prospects of coral reefs in Xisha Islands, under the influence of global marine environmental changes, should not only comprehensively consider multiple marine environmental characteristics, but also strengthen the evaluation of their morphological evolution status, original geomorphology, sedimentary dynamics processes and the impact of marine biota of coral reefs.

Key words: Xisha Islands, Coral Reefs, Coastline Change, Marine Remote Sensing, Global Change