**6. Conclusions**

This study aimed at evaluating the impact SLR would have on responses to major storm events in Saco Bay and Casco Bay in the western Gulf of Maine. A hydrodynamic model was developed to simulate the Blizzard of 1978 and the Patriots Day storm in 2007 under varying SLR scenarios to identify and track modeled storm responses. Inundation maps generated from the model results indicated a nonlinear relationship between SLR and inundation zone coverages, as the diverse slopes of the shoreline played the dominant role in determining the rate of change in inundation. Additionally, shifting circulation patterns and morphing of intertidal zones in response to SLR caused changes where river plumes were directed.

The modeled storm responses in Saco Bay and Casco Bay were primarily influenced by freshwater discharge, storm winds, and coastal structure. The percentage of inundated area changed significantly in Saco Bay under increased SLR scenarios and to a lesser degree in Casco Bay. While total inundated surface area increased in response to increased SLR, the results presented in this model study show that inundation maps generated simply from bathymetry alone do not fully capture the complexities of how SLR will impact the structure of a coastline, since they are

*Linear and Nonlinear Responses to Northeasters Coupled with Sea Level Rise: A Tale of Two Bays DOI: http://dx.doi.org/10.5772/intechopen.87780*

unable to reflect changes in circulation due to such factors as freshwater discharge. Consequently, the relationship between SLR and storm responses adopts the complex interactions between freshwater forcing, wind-induced circulation, and coastal morphology, as the dynamic structural changes experienced by the bays impact the severity of storm responses in a major way.

Many of the past studies reviewed in this paper utilized point-sourced tidal data to generalize the impact of SLR over large areas, but the results of the Saco and Casco model study suggest that there is too much variability in coastal responses to SLR to make such generalizations. Through this study, we have shown how generalizations regarding SLR miss out on the small-scale alterations in coastal structure visible in higher-resolution hydrodynamic modeling. By applying high-resolution 3D modeling techniques to this storm response study, we were able to analyze how morphological changes to a coastline induced by SLR have a direct impact on shallow water circulation and river plumes. In turn, the interactions between river plumes and storm winds were altered, producing dynamic changes in the pattern and magnitude of storm currents.

In effect, this study serves to illustrate that to properly forecast how any estuary will respond to storms under projected sea levels, it will be necessary to incorporate more complex, high-resolution, 3D hydrodynamic models than have been applied in the past. Future studies would also need to simulate more complex shallow water dynamics, such as proper wave propagation along the shoreline, to fully analyze how flood zones would change in response to SLR-induced changes in circulation patterns.
