LANDCOVER CHANGE IN MANGROVES IN THE LOWER GULF OF THAILAND: POTENTIAL LANDWARD MIGRATION DUE TO SEA LEVEL RISE

Mangrove forests are an intertidal habitat that dynamically responds to anthropogenic and natural disturbances. Rising sea levels due to climate change pose a critical threat to their existence. Nevertheless, knowledge about regional impacts on mangrove forests is limited. This study examined mangrove forest and land cover changes in Surat Thani Province in the lower Gulf of Thailand, using Thailand Earth Observation Satellite (THEOS) images from 2011 to 2021. Results showed changes in the Surat Thani mangrove forest area from 76.68 km2 in 2011 to 57.03 km2 in 2021. Mangrove forests were mainly converted to agriculture (12.91 km2), barren vegetation (7.73 km2), and aquaculture (1.57 km2). Decreased mangrove forest areas occurred inland, adjacent to community/urban areas, and along the coastline. Between January 2008 and December 2021, the sea level linearly increased by 5.28 mm/year. Concurrently, mangrove forest areas along the coastline increased by 4.63 km2 while inland growth was only 0.96 km2. These results highlight the seaward migration of mangrove forests, with less inland migration due to urbanisation within the study area.