Assessing community vulnerability and adaptive capacity for evidence based water governance in the lower Mekong basin

This study addresses growing concerns over community vulnerability and climate change adaptation in the Lower Mekong River Basin, where floods and droughts increasingly affect livelihoods and water governance. This study assesses the diversity of adaptive capacities among communities (six subdistricts in Thailand and six communes in Cambodia). We integrate geographic information systems-based spatial analysis and semi-structured interviews to analyze how differences in hydrological hazards shape that diversity. Hydrological hazards, including floods and droughts, were analyzed using a 66-year time series from the Palmer Drought Severity Index (PDSI). Socioeconomic vulnerability was assessed by the share of population and GDP exposed to flood extent. PDSI trends exhibited negative slopes across all sites, indicating a long-term drying pattern. Socioeconomic assets were concentrated in flood-prone zones: in some areas, over 90% of the population and GDP were located within 100-year return-period floodplains. Thai communities had lower exposure levels (typically < 20%). Interviews revealed that Thai communities adopted technological measures, such as underground water banking and Air Vae irrigation devices, while Cambodian communities focused on NGO-led early warning systems and manual hydrological monitoring. These findings suggest that communities facing similar climate stress follow divergent adaptation trajectories, shaped by differential access to resources, information, and institutional support.