Coastal Flood Inundation and Exposure Assessment in the Caribbean under Historical and Future High-Emission Scenarios

Coastal flood exposure indicators are increasingly needed to support climate adaptation and sustainable coastal planning in small island regions, yet regional-scale assessments that translate hydrodynamic simulations into spatially explicit exposure indicators remain limited across the Caribbean. This study develops a spatially explicit coastal flood exposure framework by integrating LISFLOOD-FP simulations with settlement dynamics, land-cover change, and population distribution data. Coastal inundation was simulated under baseline (1985–2014) and SSP5-8.5 (2015–2050) 100-year extreme sea-level conditions and overlaid with land-cover, settlement, and WorldPop data to assess land-cover, settlement, and population exposure across Caribbean island systems. The results show that SSP5-8.5 generally increases coastal inundation extent relative to the baseline, although the broad regional pattern remains similar. Large islands with extensive low-lying coastal plains show greater absolute inundation, whereas several smaller islands exhibit higher proportional exposure because of limited land area and concentrated coastal settlements. Wetlands constitute the largest share of exposed terrestrial land cover, while built-up land shows increasing exposure. These findings suggest that future coastal flood exposure in the Caribbean is shaped by both increasing hazard intensity and persistent human concentration in flood-prone coastal zones. Because the modelling framework does not explicitly represent wave setup/runup, compound flooding, or coastal defences, the results are interpreted as regional-scale screening indicators rather than locally calibrated flood-risk estimates.