The role of coastal wetlands in reducing back bay flooding: New Jersey Back Bays case study

This paper will provide an analysis of the numerical modeled water levels in the vicinity of New Jersey Back Bays (NJBB) coastal wetlands in response to wave and surge forcing. The main focus of the analysis is to evaluate the contribution of the wetlands to reduce storm and flood risk, resist and recover from storms, and mitigate for degradation of the NJBB shorelines.  In order to provide information that addresses these needs, the US Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) evaluated a set of “high” ranked Engineering with Nature (EWN)/ Natural and Nature Based Features (NNBF) measures through an application of the predictive numerical models ADvanced CIRCulation (ADCIRC) and STeady-state spectral WAVE (STWAVE) coupled via the Coastal Storm Modeling System (CSTORM-MS).

The ERDC modeling team developed a priority list of wetland configurations to evaluate, grouped into four categories: 1) Base Option designed to determine the maximum feasible benefits from a subset of NNBF measures, 2) Option 1 designed to determine how the benefits scale with NNBF size, 3) Option 2 designed to determine how the current marsh extent contributes to flood risk, 4) Option 3 designed to determine the interaction of waves with proposed NNBF measures predominantly in the Barnegat Bay area.

The above configurations were subject to wind forcing composed of a statistically-selected subset of synthetic tropical cyclones that were part of North Atlantic Coast Comprehensive Study (NACCS) storm suite. An analysis of the effectiveness of the wetland configurations was performed with respect to the following criteria: maximum surge envelopes, water level time series, and characteristics of tropical storm forcing conditions.