2:30 PM - 2:45 PM
[ACG37-04] Multi-scenario analysis quantifying the impact of sea level rise on fluvial flooding in coastal megacities
Keywords:global fluvial flooding, sea level rise, SSP-RCP scenarios, climate tipping point, hydrodynamic modelling
Climate change-driven sea level rise (SLR) will significantly impact coastal regions, affecting land use, groundwater salinity, and coastal flooding. While previous studies have primarily focused on SLR’s direct effects, such as coastal subsidence and high tide events, the influence of SLR on river hydrodynamics and amplification of fluvial flooding through backwater effects remains underexplored. In this study, we employed a global hydrodynamic model to assess how SLR amplifies fluvial flooding in coastal megacities under multiple climate and SLR scenarios.
Our results indicate that future mean inundation areas in these cities could increase by up to 11.7±9.1%, 11.3±9.4%, and 11.2±9.0% for the SSP1-RCP2.6, SSP3-RCP7.0 and SSP5-RCP8.5 scenarios by the end of the 21st century. Similarly, mean flood exposure is projected to increase by up to 11.7±9.1%, 11.2±9.5%, and 11.1±9.1%. Cities situated within 100 km of the coast exhibited the highest flood exposure, but even cities located further inland were not immune to the backwater effects due to SLR. Under climate tipping scenarios, over three-fourths of analyzed cities experienced a minimum of 141% larger inundated areas compared to projections based solely on coastal subsidence.
These findings underscore the critical need to incorporate SLR-driven backwater effects into future flood risk assessments. Ignoring this dynamic could severely underestimate the vulnerability of coastal megacities to fluvial flooding in a warming world. This study highlights the importance of comprehensive flood risk strategies for effective adaptation planning in the face of accelerating climate change.
Our results indicate that future mean inundation areas in these cities could increase by up to 11.7±9.1%, 11.3±9.4%, and 11.2±9.0% for the SSP1-RCP2.6, SSP3-RCP7.0 and SSP5-RCP8.5 scenarios by the end of the 21st century. Similarly, mean flood exposure is projected to increase by up to 11.7±9.1%, 11.2±9.5%, and 11.1±9.1%. Cities situated within 100 km of the coast exhibited the highest flood exposure, but even cities located further inland were not immune to the backwater effects due to SLR. Under climate tipping scenarios, over three-fourths of analyzed cities experienced a minimum of 141% larger inundated areas compared to projections based solely on coastal subsidence.
These findings underscore the critical need to incorporate SLR-driven backwater effects into future flood risk assessments. Ignoring this dynamic could severely underestimate the vulnerability of coastal megacities to fluvial flooding in a warming world. This study highlights the importance of comprehensive flood risk strategies for effective adaptation planning in the face of accelerating climate change.