Southeast Asia island coastline changes and driving forces from 1990 to 2015

Global climate change and high-intensity human interventions have caused significant changes in island coastline. Due to the increase in sea level rise (SLR), inundation risk of islands has attracted attention in the recent past. However, high-quality data and large-scale studies on island coastline change are very few. This study aimed at investigating island changes in South East Asia (SEA) between 1990 and 2015 using an integrated workflow, including coastline extraction, analysis of changes, and discussion of driving forces based on remote sensing technology and GIS spatial analysis. More than 9000 islands were extracted. Approximately 12% of the total islands had undergone changes in coastlines, resulting in about 251 km2 decrease in area (421 islands showed increase in area while 678 islands showed a decrease in area). Coastline length increased by 821 km from 1990 to 2015. Natural coastlines decreased by 4238 km, whereas artificial coastlines increased by 5059 km. Approximately 1/3 of total coastlines changed in location (14.9% underwent deposition and 16.1% underwent retreat). The overall land-sea pattern of SEA islands presented a “west (slightly north) to east (slightly south)” distribution, with the evolutionary process of expansion patches spanning from west to east and from south to north. Human activities, material composition and landforms of the island coast played key roles in coastline changes, whereas SLR was not associated with extensive erosion of SEA islands. Our findings form a basis for integrated management of coastal zones of SEA island countries.