Assessing Coastal Vulnerability in Southeast Asia using the InVEST Model

Southeast Asia faces unprecedented challenges as climate change and population growth accelerate the degradation of coastal and marine ecosystems, increasing risks to coastal communities and infrastructure. The region is an archipelago characterised by an extensive and densely populated coastal zone, including numerous low-lying reef islands. Such areas are highly vulnerable to coastal hazards, both present and future. Comprehensive evaluations of coastal vulnerability are therefore critical for designing effective interventions and long-term risk reduction strategies within this dynamic region. Restoration and conservation of coastal and marine habitats, such as coral reefs, mangroves, and seagrasses, offer sustainable long-term strategies for coastline protection. However, there remains a lack of essential information on the spatial and functional roles of ecosystems in mitigating coastal disaster risks. Here we assess the risk reduction capabilities of these habitats under climate change projections to identify their effectiveness for coastal protection. A Coastal Vulnerability Index (CVI) was created for the coastline of Southeast Asia (1000 m segments; 247,643 in total) using the InVEST model. Results suggest that 25.8% of the coastal areas are classified as high risk, 47.7% are at medium risk, and 26.6% are at low risk. Population data for adjacent coastal areas indicate that approximately 23.2 million individuals reside within the study region, with an estimated 19.6%, 48.4%, and 32% individuals classified under low-, medium-, and high-risk categories, respectively. Model simulations highlight the critical role of natural habitats in mitigating exposure. Preserving habitat functioning reduced exposure by 22%, underscoring the importance of healthy ecosystems for risk reduction. Our findings suggest that coastal and marine ecosystems provide positive protective benefits within remote coastal settings. Natural habitats are therefore an effective strategy to address climate change and enhance resilience to coastal hazards in the region.