Conceptual Model for Back-Bay Inundations

Extra-tropical storms ("nor'easters") inundate back-bay areas along the east coast of the United States. A simple analytical model is developed to simulate the sea-level response of small tidal embayments to nor'easters. The model's formulation assumes a weekly nonlinear pumping-mode response. The modeled response to subtidal forcing associated with extra-tropical storms has low-pass filtering characteristics - similar to the tidal response but with higher cut-off frequencies. For hydraulically constricted systems (i.e., systems having relatively small inlet cross-sections or large basins), the model simulates a damped tide and surge response, with the low-frequency surge damped less than the tide. For unconstricted systems, the model simulates a nearly unattenuated tide and surge response and a relatively high vulnerability to coastal flooding. Model results are summarized in the form of nomograph curves for various inlet/bay configurations and coastal storm characteristics. Results are compared both to numerical model simulations and to field data collected during a recent nor'easter.