Global application of a regional frequency analysis to extreme sea levels

• DOI: 10.5194/nhess-24-2403-2024
• Publication Date: 2024-07-16T11:22:34Z
• Authors: Thomas P. Collings; Niall D. Quinn; Ivan D. Haigh; Joshua Green; Izzy Probyn; Hamish Wilkinson; Sanne Muis; William V. Sweet; Paul D. Bates
• Keywords: Frequency analysis

Abstract. Coastal regions face increasing threats from rising sea levels and extreme weather events, highlighting the urgent need for accurate assessments of coastal flood risk. This study presents a novel approach to estimating global level (ESL) exceedance probabilities using regional frequency analysis (RFA) approach. The research combines observed modelled hindcast data produce high-resolution (∼1 km) dataset ESL probabilities, including wave setup, along entire coastline (excluding Antarctica). methodology presented in this paper is an extension framework Sweet et al. (2022), with innovations introduced incorporate setup apply method globally. Water records tide gauges reanalysis surge are integrated ocean reanalysis. Subsequently, these regionalised, normalised, aggregated then fit generalised Pareto distribution. distributions downscaled local scale tidal range at every location obtained model. results show 8 cm positive bias 1-in-10-year return when compared individual gauges. RFA offers several advantages over traditional methods, particularly limited observational data. It overcomes challenge short incomplete by substituting long historical collection shorter but spatially distributed records. These not only retain volume information also address issue sparse gauge coverage less populated areas developing nations. process illustrated Cyclone Yasi (2011) as case study, demonstrating how can improve characterisation ESLs prone tropical cyclone activity. In conclusion, provides valuable resource quantifying risk, offering innovative that contribute preparing – mitigating against flooding.