Mikkelsen C1977) suggested that three conditions may have contributed to the 

 Limfjord profile development: (a) The borrow sand was coarser than the native 

 sand; (b) the groins acted as impermeable barriers and cut off longshore drift 

 away from the site; and (c) a higher-than-normal frequency of offshore winds 

 may have occurred, thus aiding onshore bedload wave transport. 



II. FIELD PROCEDURE AND DATA ANALYSIS 



1. Geographic Setting . 



The entrance channel to New River Inlet, located approximately 60 kilometers 

 northeast of Wilmington, North Carolina, was the dredging site for this study 

 (Figs. 3 and 4). The disposal site was located 2 kilometers southwest of the 

 inlet along West Onslow Beach. The beach throughout this vicinity is approxi- 

 mately 60 meters wide and backed by a vegetated foredune. The study site is 

 located at the northeastern part of a barrier island, which is only slightly de- 

 veloped with a scattering of private dwellings in the vegetated barrier flat 

 landward of the foredune. The beach is used solely for recreational purposes. 

 A fishing pier, located 3.5 kilometers southeast from the inlet, is the only 

 structure present along this section of coastline. 



2. Disposal Procedure. 



During the period, 19 July to 13 August 1976 (26 days), 26,750 cubic meters 

 of sand was dredged from New River Inlet (Figs. 2 and 3), transported to the dis- 

 posal site by the Curvituak , and placed along a 210-meter coastal reach within 

 the study area. Although the Cicrvituok has a minimum water depth capability of 

 about 2 meters, a tidal range of about 1 meter and varying swell conditions re- 

 sulted in the actual disposal area extending from the 1.8- to 4.0-meter depth 

 contour mean low water (MLW) . A 30-meter-wide shore-normal zone, in which no 

 sediment was to be placed, flanked both sides of the disposal reach. Some sedi- 

 ment, though, was inadvertently placed within the southwest flank, between ranges 

 -9+00 and -10+00, beyond the designed disposal limit. Monitoring of the study 

 area began a week before disposal and extended through and subsequent to the dis- 

 posal period until 19 October 1976, 71 days following the final disposal date 

 (Figs. 5 and 6) . 



3. Survey Data . 



A 270- by 300-meter area spanning the beach and nearshore zone was selected 

 for measuring combined beach and nearshore profiles. The shore-normal dimension 

 (300 meters) extended from the base of the foredune [y +3 meters MLW) seaward 

 240 to 270 meters beyond MLW to an approximate water depth of -4.5 meters MLW. 



Profiles extending across the beach and nearshore zone were measured at 30- 

 meter intervals. The beach of each profile was measured using standard rod and 

 tape surveying techniques. A stadia board attached to a towed, bottom-riding 

 sea sled was used to obtain bathymetric data seaward of the beach (Musialowski, 

 Schwartz, and Teleki, 1977). The sled was towed seaward from the beach along a 

 survey range line by an amphibious vehicle (LARC-V) and detached at an offshore 

 point. Position and elevation data were recorded as the sled was pulled land- 

 ward by a shore-based winch. In several cases, the sled moved slightly off line 

 which led to outer profile variability in the true position and shape of profile 



13 



