Yergeau, Steven E.. Development and application of a coupled SWMM-MODFLOW model for an urban wetland. Retrieved from https://doi.org/doi:10.7282/T3J1039P
DescriptionKearny Marsh is located within the Hackensack Meadowlands and since it was formed almost forty years ago, has been negatively impacted by activities that have altered its hydrology (ditching, urban stormwater infrastructure, construction of the western spur of the New Jersey Turnpike). The primary goals of this research were to characterize existing hydrology of Kearny Marsh, to predict effects on marsh hydrology of proposals to redevelop and reuse the site, and to project future marsh water levels under drought and high precipitation conditions. To analyze various components of this complex system, a Storm Water Management Model (SWMM) surface water model and a Visual MODFLOW groundwater model were developed, calibrated, and validated. SWMM was linked to MODFLOW through exchange of evapotranspiration and infiltration data between the models. The coupled models provided water budgets for Kearny Marsh in order to characterize its hydrology. The validated SWMM and MODFLOW linked models were used to simulate hydrological impacts of a slurry wall around Keegan Landfill and redevelopment of portions of the wetland. Results from field measurements and model simulations indicate that Kearny Marsh is a groundwater discharge wetland with a shallow groundwater table. Groundwater flow is in an eastern direction, towards the Hackensack River. Flow velocities are slow, which are consistent with measured hydraulic conductivities. Hydrology is also influenced by tidal action that affects flooding frequency in the surrounding area. A broken bulkhead between Kearny Marsh and Frank's Creek allows for additional water inputs into the marsh when high tides are occurring. If this situation is coupled with a storm event, flooding may occur in surrounding areas. This was both predicted in the SWMM model and observed in the field. This combination of a shallow water table that gets elevated during storm events, development reducing the areas available to infiltrate stormwater, and drainage deficiencies due to the broken bulkhead connecting Frank's Creek and Kearny Marsh account for flooding reported in Kearny, NJ. Proposed development and installation of a slurry wall around portions of Keegan Landfill was predicted to create hydrologic changes that are consistent with urban impacts (increased flows, decreased infiltration and increased evaporation).