5 Circulation Analysis
This chapter describes calculations of circulation and water level at Mattituck
Inlet and Goldsmith Inlet performed to infer and interpret sediment-transport
pathways associated with tidal flow. Field measurements (Chapter 4) made in
October 2002 of bathymetry, water level, and current provided data for driving
and validating the models.
For Mattituck Inlet, tidal hydrodynamics (water level and current) were
simulated with the ADvanced CIRCulation (ADCIRC) model (Luettich et al.
1992), a two-dimensional (2-D) finite-element hydrodynamic model that
calculates the depth-averaged horizontal circulation. For Goldsmith Inlet, tidal
hydrodynamics were modeled with DYNLET (DYNamic Implicit Model of One-
Dimensional Tidal Flow Through InLETs) (Amein and Kraus 1991), which is a
one-dimensional (1-D) finite-difference model suited to narrow inlets and areas
with minimal cross-channel and cross-bay circulation.
Water-surface elevation and current velocity for the Long Island Sound,
Mattituck Inlet, and Mattituck Creek were calculated with ADCIRC. A regional
ADCIRC grid of the New York Bight and the Long Island Sound (Figure 5-1)
developed in the Coastal Inlets Research Program (Militello et al. 2000) was
modified by increasing resolution at the study site and incorporating data from
the October 2002 bathymetry survey at Mattituck Inlet. The model was then
validated against regional and local measurements.
The finite-element ADCIRC grid allows fine resolution to be specified in
areas of interest. The model domain for this study incorporated horizontal grid
elements with lengths ranging from 2.8 km along the Atlantic Ocean southeastern
model domain boundary to less than 10 m within Mattituck Creek. The model
grid consisted of 15,113 nodes and 27,851 elements. The ADCIRC grid for the
study area is shown in Figure 5-2, and the grid for Mattituck Inlet and Mattituck
Creek is shown in Figure 5-3. The regional grid assures input of reliable forcing
to accurately reproduce tidal phasing and amplitude.
Chapter 5 Circulation Analysis