Flooding of Indian River Bay and Rehoboth Bay through Indian River Inlet and by wave overtopping of Barrier Beach

Abstract

A simple analytical model for a small bay with a tidal inlet channel is developed to predict the peak stillwater elevation in the bay for the given peak stillwater elevation and surge duration in the ocean. The model is applied to the Delaware Atlantic coast where three bay tide gauges together with one ocean tide gauge have been in operation since 2005. 27 storms identified during 2005 – 2015 are used to calibrate a dimensionless parameter related to the inlet and bay characteristics. The calibrated model predicts the peak stillwater elevation within 10% errors at two bay gauges and within 30% errors 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 are predicted using the cross-shore numerical model CSHORE. The analytical model including wave overtopping predicts the peak stillwater elevation increase of 0.1 – 0.2 m in the bay. The coupled approach is useful in evaluating bay flooding risk during extreme storms in efficient manners.