Coastal resilience and island habitability in coral reef islands: A case study of Lakshadweep Islands

Low-lying coral reef islands are increasingly threatened by sea-level rise and intensifying monsoon events, leading to heightened risks of coastal inundation, erosion, and consequent impacts on island habitability and human migration. Despite these challenges, such islands exhibit dynamic and non-uniform responses governed by local hydrodynamics and environmental conditions. The Western Indian Ocean is especially vulnerable, with models projecting anomalously higher rates of sea level rise and storm frequency compared to the global average. Within this context, the low-lying islands of the Lakshadweep Archipelago provide an essential case study for understanding island vulnerability and resilience.

This study presents a decadal-scale analysis (2003–2022) of ten islands in the Lakshadweep Archipelago, focusing on spatial variations in island area and their relationship with global and regional environmental factors. High-resolution satellite imagery (CNES Airbus, 0.3–0.7 m) was used to examine shoreline morphological changes on both inhabited (Bitra, Androth, Minicoy, Agatti, Kavaratti, Kalpeni) and uninhabited (Bangaram, Thinnakara, Suheli, Kalpetti) islands. Islands were categorized by size, distinguishing large (>1 km², Minicoy and Androth, Kavaratti, Agatti, Kalpeni) from small (<1 km²) islands, and by habitability to assess anthropogenic impacts. Results reveal that all islands, regardless of habitation, experienced specific changes in area: small islands showed up to 30% sediment migration, however, without losing area—especially pronounced from 2007 to 2017, coinciding with severe El Niño and low-amplitude Indian Ocean Dipole events. While the large islands lost up to 5% of their area, attributed to both natural and human influences.

These findings indicate that small islands face moderate risk due to sediment migration, while large islands are moderately to highly vulnerable, influenced by persistent erosion and anthropogenic factors. Spatial patterns of vulnerability, particularly in the southern zones, underline the need for targeted mitigation and adaptation strategies. Importantly, regional drivers such as monsoon intensity play a decisive role in shoreline resilience, differentiating these islands from their global counterparts. By identifying areas of risk and proposing conceptual models for adaptation, this study offers insights for assessing the habitability of coral reef islands in the context of ongoing climate change.