Climate change is believed to have increased the intensity and frequency of heavy rainfall, and also to have caused sea level rises over this century and beyond. There is widespread concern that small-island nations are particularly vulnerable to increasing risk of inland flood due to such climate change. Understanding the impact of climate change on flood hazard is of great importance for these countries for the development of better protection and adaptation strategies. This study conducted a case study focusing on the impact of climate change on flood hazard at Faleolo International Airport (FIA), Samoa. FIA is a typical small islands airport, located on the lowland along the coast fronted by a fringing reef. Annual maximum daily rainfalls for different return periods were first estimated for the present and future climate around FIA. The estimated rainfalls were input as the forcing of a two-dimensional flood inundation model to investigate the flooding behavior and effectiveness of probable drainage systems. Results showed that a part of the runway can be inundated under heavy rainfall. Construction of drainage pipes significantly contributes to reducing the flood hazard level. Sensitivity analysis showed that the astronomical tide level has relatively little influence on the performance of the drainage system, while the combination of sea level rise and the sea level anomaly induced by stormy waves on the fringing reef could have non-negligible impacts on the drainage system. Location of the drainage pipe is also important to effectively mitigate flooding. The time-concentration of torrential rainfall may also significantly impact the overall performance of the drainage system.

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