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|Title:||Improvements for Murrells Inlet, South Carolina : hydraulic model investigation|
|Authors:||United States. Army. Corps of Engineers. Charleston District.|
Perry, Frederick C.
Seabergh, William C.
Lane, Edgar F.
|Publisher:||Hydraulics Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-78-4.|
Abstract: Murrells Inlet, located 13 miles southwest of Myrtle Beach, South Carolina, is a natural channel through a sandy beachline that conducts tidal flows between the Atlantic Ocean and a well-mixed lagoon of ocean salinity surface which has no source of freshwater inflow other than local runoff. The inlet provides passage from the ocean to docking facilities for charter craft, commercial fishing vessels, and private boats. However, due to the influx of sand into the inlet, an environment of shallow shifting-sand shoals and breaking waves produces difficult and dangerous navigation conditions. A project for the improvement and stabilization of the inlet was authorized in November 1971. A model study was performed to aid in preconstruction planning and design of structural solutions to the problem of providing a stabilized channel of sufficient depth and width with provisions for sand bypassing. The Murrells Inlet fixed-bed model, constructed of concrete to scales of 1:200 horizontally and 1:60 vertically, accurately reproduced the lagoon and a region of the ocean near the inlet, an area of approximately 14.2 square miles. After a least-squares harmonic analysis of prototype tidal data for amplitude and phase of various tidal constituents, a successful hydraulic model verification was made based on the M₂ constituent. The model study examined a variety of plans in order to optimize the alignment and spacing of jetties and the proper alignment of interior channels with respect to current patterns. Also, the effects of the plans on bay tidal elevations and tidal currents were determined as were the effects on wave heights. Model testing concluded that plan 1H was the optimal plan for providing a stable entrance channel while providing for sand bypassing. The plan included : (A.) A north quarrystone jetty composed of a 1,330-ft-long low weir section constructed to a +2.2 ft mlw elevation flanked by a 1,505-ft-long seaward section and a 518- ft-long shoreward section, each with a top elevation of +9.0 ft mlw. (B.) A 3,330-ft-long south quarrystone jetty with a top elevation of +9 ft mlw. Also an 8-ft-wide fishing walkway will be constructed on the crest of the south jetty to el +10 ft mlw. (C.) Sand dikes connecting the shoreward ends of the jetties to the dune line. (D.) A 20-ft-deep deposition basin of 600,000-cu-yd capacity dredged adjacent to the low weir section on the inlet side. (E.) A 300-ft-wide by 10-ft-deep entrance channel. (F.) A 200-ft-wide, 10-ft-deep inner channel connecting the entrance channel to the mouth of Main Creek, where it joins a 90-ft-wide, 8-ft-deep channel that extends 13,590 ft to the Army Crash Boat Dock. (G.) A 200-ft-wide, 10-ft-deep auxiliary channel connecting the entrance channel to the mouth of Oak Creek. (H.) A training dike of variable height which flanks the lagoon side of the deposition basin in order to prevent tidal currents from passing through the basin. The plan would not have a significant impact on tidal conditions, with maximum changes of 0.3 ft in bay tidal amplitudes, 0.2 ft in mean tide level, and 11 min in tidal phasing. Also there would be no significant change to the inlet's tidal prism. NOTE: This file is large. Allow your browser several minutes to download the file.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Technical Report|
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