Bay Flooding through Tidal Inlet and by Wave Overtopping of Barrier Beach

Abstract

A simple analytical model for a small bay with a tidal inlet channel was developed to predict the peak still-water elevation in the bay for the specific peak still-water elevation and surge duration in the ocean. The model was applied to the Delaware Atlantic coast where three bay-tide gauges, together with one ocean-tide gauge, have been in operation since 2005. Twenty-seven storms identified between 2005 and 2015 were used to calibrate a dimensionless parameter related to inlet and bay characteristics. The calibrated model predicted the peak still-water elevation within 10% error at two bay gauges and within 30% error at the third bay gauge. Wave overtopping and overwash over the barrier beach between the ocean and bay occurred during Hurricane Sandy in 2012. Wave overtopping and barrier beach evolution were predicted using a cross-shore numerical model. The analytical model including wave overtopping predicted the peak still-water elevation increase of 0.1–0.2 m (10–20%) in the bay. The coupled approach is useful in evaluating bay-flooding risk for given storm statistics for the ocean.