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Published: 2001

Total Pages: 212

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Shinnecock Inlet, New York, is a dual-jettied inlet located on the south shore of Long Island connecting Shinnecock Bay to the Atlantic Ocean. The down-drift beach, west of the inlet, experiences chronic erosion, and cost-effective and innovative measures for beach nourishment are being examined by the U.S. Army Engineer District, New York. The feasibility of mining of the flood and ebb shoals to serve as sources of material was examined in this report. Emphasis is on the concept of 'flood-shoal engineering' within an integrated inlet and beach system. Fifteen action alternatives were developed that involved dredging, modification of the jetties, and combined dredging and structural changes. The alternatives were evaluated by their potential changes to navigation conditions, availability of material for placement on the beach, changes to inlet and channel currents that would modify scour and deposition patterns, and changes in current strength near the beach that would modify erosion. The area of compatible material, established for the flood shoal from analysis of core samples, was the targeted mining area for the study and contains approximately 1.8 x 10(exp 6) cu yd of beach-compatible sand. Exploratory alternatives were also evaluated that involved dredging in other locations. Evaluation of alternatives was conducted through circulation, wave, and morphology modeling. A calibrated circulation model was applied to simulate each alternative and compare current strength and patterns to those for the existing condition. Wave modeling was conducted for one alternative that consisted of mining the attachment bar to determine changes in the wave patterns near the shore. Morphology modeling was conducted to calculate the long-term recovery rates of the system to mining of the flood shoal.