Mapping the return periods of extreme sea levels: Allowing for short sea level records, seasonality, and climate change

This study of extreme sea levels is motivated by concern over increased coastal erosion and flooding under plausible climate change scenarios. Extremal analyses are performed on the annual and seasonal maxima from 24 tide gauge stations in the Northwest Atlantic. At data poor locations, a 40 yr surge hindcast and information from short observation records are used to reconstruct sea level records prior to the annual and seasonal analysis of extremes. A Digital Elevation Model is used to generate spatial maps of the return period of extreme sea levels associated with specified flooding probabilities under current conditions and under projected global sea level rise scenarios for the next century. It is the first time such maps have been produced. Their primary advantage is that extreme sea levels are expressed in terms of inundated areas as opposed to a critical flood value about an arbitrary datum. Another novel aspect of this study is that the extremal analyses are carried out for specific seasons.