Storm surge contributions to flood hazards on Canada's Atlantic Coast

Abstract

A numerical hydrodynamic model was used to simulate the generation and evolution of storm surges in Atlantic Canada in response to synoptic-scale surface wind and atmospheric pressure fields. The modelling was conducted as part of a broader initiative to support community-scale inundation modelling and coastal flood risk assessment for communities located in the Acadian Peninsula region of New Brunswick. The 44 largest storm surge events on record at a tide gauge proximate to the region of interest were simulated using the numerical model. Initially, a comparison between simulated storm surges and peak non-tidal residuals from tide gauge records showed relatively poor agreement, producing an R2 value of 0.403. Model skill was improved by incorporating the influence of sea ice cover on air-sea momentum transfer in the hydrodynamic model, and improved correlation with measured residuals was obtained by adding estimates of wave set-up to the predicted storm surges, ultimately resulting in an R2 value of 0.803. The results of the simulations provided a basis for identifying distinct regional factors affecting storm surges and water level residuals and demonstrated conditions where wave set-up and sea ice cover play an important role in contributing to extreme high water levels.