Irene Simulations, in Ranges of Peak Storm Tides between Open-Coast and Bay Locations

SUMMARY: This library contains the model output (including unstructured finite-element mesh, atmospheric forcings, and output files with time snaps) for simulations of storm tides in and around the southern Chesapeake Bay. The ADvanced CIRCulation (ADCIRC) model was used for the simulations, which used atmospheric forcing from a parametric vortex model of Hurricane Irene (2011) and perturbations of wind speed, storm size, storm forward speed, track translation, and track rotation. Simulations were completed on the NC State cluster (Hazel). These simulation data support a journal manuscript (Knowles et al., in review).

ABSTRACT: Storm tides – the combination of tides and storm surge - cause flooding in coastal regions, often with differences in magnitudes between the open coast and locations within water bodies like bays and estuaries. Previous studies have shown that storm surge is sensitive to the storm’s wind intensity, speed, and track; the coast’s geometry and relative position to the storm; and also to nonlinear interactions with tides. These sensitivities have been documented at either open coast or bay locations, but without comparing or quantifying the differences in behavior between them, even though these differences may have implications for risk management.

This study examines the range of peak storm tides within the Lower Chesapeake Bay, which has vulnerable communities at the open coast, like Virginia Beach, and inside the bay near the James River, like Hampton and Norfolk. A high-resolution model was developed for the region and validated against observations of water levels during Hurricane Irene in 2011. Storm parameters were perturbed to analyze the variation in storm tide ranges. It was found that the range of possible storm tides was greater at bay locations than at the open coast, by as much as 47%. This higher variability at the bay locations was due to sensitivities to storm parameters like the wind intensity and storm tracks, which led to storm tide peaks outside of the inter-quartile range. This finding highlights the importance of understanding the uncertainty in storm forecasts concerning future possible impacts in complex coastal regions.