Moriches Inlet, Long Island, New York

PRINCIPLE INVESTIGATORS:

·  Dr. Gary A. Zarillo

·  Mr. Kenneth J. Connell

Background

Moriches Inlet is located on the south shore of eastern Long Island, New York approximately 83 km west of Montauk Point, and about 105km east of New York City. The inlet separates the eastern tip of Fire Island from western tip of the Westhampton Beach barrier island. Moriches inlet was opened near its present location in 1931 after a strong extratropical storm. Jetties were constructed at the inlet in 1953 to stabilize the inlet channel. However, groins placed on Westhampton Beach, updrift of the inlet, have contributed to three barrier island breaches (one in 1980 and two in 1992) in the vicinity of Moriches Inlet due to the reduced sediment supply feeding the beaches downdrift of the groins.

The objective of this study is to analyze the hydrodynamic and morphodynamic processes at Moriches Inlet and attempt to establish an understanding of the forces driving morphologic changes in the inlet system. A numerical model is being employed to computationally describe the complex morphodynamic processes surrounding the inlet.

Circulation and Transport Model

The hydrodynamic model used in this study is a two-dimensional, depth-integrated finite-difference circulation model entitled M2D. M2D may also be coupled with a steady-state spectral wave model known as STWAVE in order to represent the contribution the waves have on circulation and sediment transport. A rectilinear model grid with variable resolution will be used to numerically portray the Moriches inlet vicinity including Moriches Bay and a portion of the Atlantic Ocean. The boundary conditions of this grid will be driven by time series measurements for water surface elevations and wave-spectra. Model runs of varying length will be made to demonstrate various hydrodynamic and morphological features of this inlet system.

Model Output


Moriches Inlet Flood Water Elevations
Moriches Inlet Ebb Water Elevations
Moriches Inlet Wave Heights and Direction

 


If you are unable to view the two animations above, you may download the water elevation animation hereand the topographic change animation here.

Waves

In addition to the numerical model runs, statistical analysis of wave and sea-level data are being examined for patterns that may indicate triggering mechanisms for morphological change at Moriches Inlet. Topographic data and historical aerial photosets were analyzed for spatial and temporal changes in the region.
Net Sediment Transport Cummulative PLS Plot
The figure above shows the Net Sediment Transport Direction derived from Cummulative Wave Power and Direction from The Westhampton Wave Gauge in 1998.
Joint Probability Plot
The figure above shows the Wave Power vs. Wave Direction Probability Distribution Spectrum for The Westhampton Wave Gauge in 1998.

Contact Dr. Gary Zarillo