Bathymetric and Pier Surveys 



Collection 



54. Beginning in July, a series of profiles was obtained monthly using 

 the Coastal Research Amphibious Buggy (CRAB), a 12-m-tall amphibious tripod, 

 and a Zeiss Elta-2 total station surveying system. Detailed characteristics 

 of this system are presented in Birkemeier and Mason (1984). Each profile 

 extended seaward from the baseline behind the dune to a water depth of about 

 10 m, and profiles were located up to 0.6 km north and south of the FRF pier. 

 The profile lines surveyed are located and identified on each contour diagram 

 in Appendix C. The accuracy of these surveys was about +3 cm horizontally and 

 vertically. Weekly soundings along both sides of the FRF pier were performed 

 by means of a lead line surveying technique consisting of lowering a weighted 

 measuring tape and noting the distance below the pier deck, a known elevation 

 above NGVD. Positions between the pier bents (i.e., every 12.2 m) were used 

 to minimize inaccuracies due to scour near the pilings. 



Analysis 



55. The pier, beach, nearshore, and offshore data were reduced to posi- 

 tion (X,Y) and depth (Z) triplets relative to the local NGVD. The data were 

 listed, and a display of the profiles (i.e., distance along the range versus 

 elevation) using line printer graphics was generated for visual inspection. 

 After the data had been edited and determined acceptable, another set of 

 routines was used to compute contour diagrams of the bottom topography and 

 time sequences of bottom elevations at selected locations along the pier. 



Sediment Data 



Collection 



56. Sediment data were not collected routinely at the FRF during the 

 year. Coincident with an experiment in the fall, personnel from CERC, the US 

 Geological Survey (USGS) in Reston, Va., and Skidaway Institute of Ocean- 

 ography in Georgia, collected grab samples and box cores from the ocean, 

 beach, and nearshore and vibracores from the sound, across the island to the 

 ocean. The grab samples were obtained with a clam shell grab and contain 

 samples from approximately the top 10 cm of sediment. 



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