Climatological-hydrodynamic storm surge modeling for Apalachee Bay, Florida

Historical tropical cyclone and storm surge records are often too limited to quantify the local surge climatology. Paleohurricane surge sediment records may uncover long-term hurricane activity, but their interpretation is still associated with large uncertainties. Discrepancies often exist; for example, the long-term average frequency of extreme surge events was found to be much greater in the paleo record than in the historical record for the Apalachee Bay region. In this study, we extend a climatological-hydrodynamic method for estimating the frequency of storm surges of various magnitudes and apply it to Apalachee Bay. We model both historical surge events (over 160 years) and a large set of synthetic events (over five thousand years) with characteristics conforming to climatology for the area; special efforts are made to account for uncertainty in storm size estimation and to improve the efficiency and accuracy in surge simulation for large event sets. With a much higher frequency of extreme events compared to the historical record, the synthetic dataset supports the inference from the paleohurricane records that the Apalachee Bay area has been subject to routine inundation for thousands of years. The analysis also shows that the Apalachee Bay surge risk is determined by storms of broad characteristics, varies spatially over the area, and is affected by coastally-trapped Kelvin waves, all of which are important features to be considered when interpreting overwash-based paleohurricane records as well as when assessing and communicating the risk.