Coastal built-up dispersion on a Mediterranean tourism island: a multi-criteria classification of Rhodes, Greece (2006–2018)

Tourism-intensive islands face strong pressure on limited and environmentally sensitive coastal land. This study examines where built-up change was concentrated on Rhodes Island between 2006 and 2018. Instead of applying a fixed coastal buffer, the coastal zone was delineated by combining distance from the coastline, elevation, a 5 m contour line and official settlement boundaries. The resulting classification contains four core typologies based on terrain and settlement status, together with a residual Other Coastal Zone that ensures complete spatial coverage. Built-up surfaces were represented by a proxy derived from the Copernicus Imperviousness Density status layers for 2006, 2012 and 2018, harmonized to a 20 m grid and classified using a 30% imperviousness threshold. Built-up change was stronger outside settlement boundaries and was particularly concentrated in coastal areas. In the Ex-urban Flat Coastal Zone, the IMD-derived built-up proxy increased by 41.03% between 2006 and 2018, more than in any other typology. The findings identify flat coastal land outside official settlement limits as the main concentration of built-up dispersion on Rhodes. The method can be applied to other Mediterranean islands to support more targeted monitoring and spatial planning.