Effect of metro rail extension on flood risks of Bangkok Metropolitan Authority outskirt due to climate and land use land cover changes

The expansion of Bangkok Metropolitan, driven by economic growth, includes extending metro systems.These changes, alongside a denser population and higher waste generation, have compromised drainage efficiency, amplifying flood vulnerability. Focused on the Pink Line's 34.5-km stretch from Khaerai intersection to Minburi, this study aims to evaluate the Flood Vulnerability Index (FVI) near the metro line, identify critical factors influencing vulnerability, and propose mitigation strategies. The analysis divided the study area into five distinct zones based on area characteristics, then evaluated the FVI according to existing conditions of population density (PO), drainage efficiency (DE), impervious ratio (IR), garbage management (GB), and pond area ratio (PA). It was found that the FVI values ranged from 0.41 to 0.55, and the sensitivity analysis indicated Lat Pha Khao and Ramindra km.4 stations have minor FVI impact due to DE and IR. Conversely, improvements in PA and GB reduced the FVI at Khubon and Eastern Ring Road stations. Consistent FVI is observed with PA and IR enhancements but fluctuates with GB and DE changes. At the Minburi Market Station, the increased IR has a minor FVI impact, while enhanced DE and PA significantly lower the FVI.The degree of factor sensitivity is advantageous for planning local mitigation strategies.