40 



most frequently traversed profile line is only now approaching 350 surveys 

 (Howd and Birkemeier 1987). 



In SUPERTANK project planning, it was considered essential to develop a 

 survey system that would withstand intensive use and allow rapid surveying 

 and immediate capture and examination of the data. Budgetary restrictions 

 and the uniqueness of SUPERTANK precluded development of a fully auto- 

 mated system. Instead, a labor-intensive, semi-automated survey system was 

 devised. This chapter describes the beach profile survey instrumentation, 

 measurement procedure, and selected properties of the profile data set. Infor- 

 mation on the beach sediment is also given. The beach profile survey data are 

 listed in Appendix B of Volume II of this report, together with plots of the 

 profiles taken along the center line of the channel. Chapter 12 discusses 

 associated pore pressure and sediment density measurements. 



Experiment Apparatus 



At SUPERTANK, the beach profile was surveyed with an auto-tracking, 

 infrared Geodimeter, a commercially available instrument, that was brought in 

 for use in the project and positioned at the beach end of the channel. The 

 Geodimeter targeted a prism attached to the top of a survey rod mounted on a 

 manually operated carriage. The survey rod, which moved freely in a sup- 

 porting roller guide, made contact with the bed through a pair of wide-tread 

 pneumatic rubber wheels. The main components of the survey system were 

 the rod with guide that was affixed to the carriage, the Geodimeter located 

 outside the northern end of the wave channel (landward side of the beach), 

 and a portable personal computer (PC) connected to the Geodimeter. The 

 carriage rode on top of the channel walls and was dedicated to profile 

 surveying. The basic survey system was developed by the third author of this 

 chapter, and the survey rod and guide were designed and fabricated in the 

 machine shops at WES. The system was modified and refined onsite during 

 the mobilization week of SUPERTANK. 



Survey rod 



Figure 2-1 is a cross-section schematic of the survey rod and a portion of 

 the carriage, as viewed from the Geodimeter position. There were two con- 

 cerns in designing and operating the survey rod: disturbance of the sand bed 

 and flexure of the rod. Minimization of bed disturbance was addressed by 

 terminating a hollow, airtight aluminum rod with pneumatic tires, providing 

 sufficient buoyancy such that the tires did not notably disturb the bottom 

 under the weight of the rod. Minimal penetration of the wheels into the 

 wetted sand bottom was confirmed visually along the shallow ends of the 

 profile and on the subaerial beach, and by divers observing the action of the 

 wheels in the deeper end of the channel. 



Chapter 2 Beach Profile Surveys and Sediment Sampling 



