Najarian Associates conducted a numerical modeling
study to support Woodbridge Township’s effort to restore a 33-acre
marsh located along upper Woodbridge Creek– a tidal tributary to the Arthur
Kill and the New York/New Jersey Harbor Estuary.
The goal of these analyses was to determine how
proposed physical alterations to the site (i.e., dike removal,
channel dredging and site re-grading) would affect both marsh
inundations and salinity intrusions. Towards this objective, the
Najarian team analyzed continuous tide and salinity data at several
Creek locations.
Results indicate that the restoration area is characterized
by: (1) a limited (1+ foot) tidal range; and (2) a variable
salinity range (typically 0-15 psu), with nearly freshwater
conditions prevailing following typical rainfall events. This combination of
low-salinity conditions and low-tide exposure limits the selection
of available marsh plantings.
The
Najarian team adapted a two-dimensional, finite-element,
hydrodynamic and salt transport model to the study area. The model was calibrated
with continuous tide and salinity data. The model accurately
reproduced observed tidal patterns, including the attenuation of
upper Creek tidal ranges.
The calibrated model was used to simulate Woodbridge Creek
tides and salinities for various proposed site alterations,
including: (1) removal of existing dikes; (2) constructing a new
marsh channel; and (3) re-grading (i.e., lowering) higher site
elevations to provide a more expansive and beneficial inter-tidal
zone. Model results indicated that the proposed modifications would
marginally impact the site’s tidal regime, including the frequency
and duration of marsh inundations.
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Najarian Associates
