Presenter: Deborah Crowley (University of Rhode Island)

Description:
Nor’easters are extratropical storms characterized by strong winds, often with intense precipitation, that frequently occur in New England. The meteorological conditions associated with nor’easters generate sustained periods of increased wave action and storm surges. The extended duration of nor’easters is such that storm effects typically coincide with one or more high tide, thereby increasing the likelihood that peak water levels will induce coastal flooding. Climate change driven rising seas will result in a change of water levels, inundation footprints and the nearshore bathymetry from tides alone. During storms these factors will lead to changes in the nearshore wave climate. Since wave generated radiation stresses influence storm surge water levels, peak storm surges during nor’easters will be affected by both the change in the mean sea level as well as the changes in the wave heights resulting from rising seas. This study uses the ADCIRC-SWAN model system to investigate the contributions from waves on storm surges during nor’easters for a range of mean sea levels. Simulations were performed of two different nor’easters, occurring in January and March 2018 respectively, which both resulted in coastal flooding in New England. Simulations were performed for each storm both with and without waves for a range of mean sea levels ranging up to 1 m above the present mean sea level. Simulations with waves were run using ADCIRC coupled with SWAN while simulations without waves were run using ADCIRC alone.  Comparisons of the predicted water level from all simulations were performed to isolate the effects of waves on the total water level. The results from each mean sea level were compared to further provide insights on how the contributions from waves on storm surge water levels will change from sea level rise.