ABSTRACT

Cialone, M.A. and Slusarczyk, G., . Impact of inlet closures on surge response in New Jersey back bays.

The in-depth study presented in this paper includes numerical modeling and analysis of the effects of storm surge barriers (inlet closures) on water levels in the back bays of New Jersey during storm events. Eleven inlet closures were each numerically “closed” singularly and in combination with other inlet closures. Storm surge simulations were run with all 11 inlets “open” as a base condition and for each of the inlet singular closure and combination closure conditions. In this paper, four combinations of inlet barrier positions were selected to demonstrate the ability of surge barriers to potentially prevent surge propagation into the back bays of New Jersey, including: (1) the base condition (all inlets open); (2) closing one of the larger entrances, Barnegat Inlet; (3) all inlets closed except for a small inlet (Corson Inlet) and an extremely wide inlet entrance (Little Egg/Brigantine Inlet); and (4) all inlets closed. A comparison of maximum surge envelopes and water-level time series from simulations of 10 synthetic tropical storms with the inlets in these four configurations was made. Three of the largest bay systems, Barnegat Bay, Manahawkin Bay, and Little Egg Harbor, are the main focus of this paper. As expected, the greatest reduction in water level in the bays occurs when all inlets are closed with surge barriers. The average reduction in water level for the three bays mentioned above with all inlets closed is 0.70 m, with a maximum average reduction in Little Egg Harbor of 0.73 m. Simulations with only Barnegat Inlet closed show the greatest reduction in water level in the northern portion of Barnegat Bay, whereas surge can still propagate into the southern portion of the bay through Little Egg/Brigantine Inlet. However, storms with strong N-to-S wind can inhibit flow entering from the open inlet at Little Egg/Brigantine and therefore show the greatest reduction in maximum water level in the southern portion of Barnegat Bay for these conditions. With some inlets open and some closed, strong alongshore winds can also cause surge to become trapped behind adjacent inlet closures. This demonstrates the importance of considering multiple means of flow propagation into an embayment as well as the timing of implementing surge barriers to optimize surge protection.

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