c. Offshore measurements that centered around acoustic instruments, a 

 laser-Doppler velocimeter (LDV), and instrument tests. 



As described above, participants joining CERC at SUPERTANK came 

 from universities, private research institutes, and industry. Many of these 

 participants have contributed to this data report. In addition to the principal 

 investigators and the teams from their institutions, students and other interest- 

 ed parties from Seatech, Inc., the University of California at Santa Cruz, the 

 University of Delaware, and the University of Washington also participated. 

 Observers were sent from the Danish Hydraulics Institute (Denmark) and the 

 Delft Hydraulics Laboratory (The Netherlands). US ACE personnel from 

 several field offices also assisted SUPERTANK investigators in the data col- 

 lection. 



Project Procedure 



SUPERTANK ran for the 8-week period from 29 July to 20 September 

 1991. The first and last weeks were dedicated to mobilization and demobili- 

 zation, and waves were generated and data collected over the 6 weeks from 

 5 August through 13 September. Two 1-week trials of instruments were con- 

 ducted 6 months and 1 month before the start of SUPERTANK. The steering 

 committee encouraged participation in these instrument trials by all investiga- 

 tors to assure proper deployment and operation of the instruments, as well as 

 to eliminate instrument cross talk and interference prior to the full deploy- 

 ment. These valuable shakedown trials allowed correction of instrument prob- 

 lems, improvements in mountings, and more detailed planning of the logistics 

 of full instrument deployment. The instrument shakedown trials were the 

 primary reason that data collection proceeded without major problems and 

 little instrument downtime. 



The channel was filled with sand the week prior to mobilization. Sand 

 was trucked from the Oregon coast and placed in the channel with front 

 loaders. The channel was first partially filled with water so that the sand 

 would fall through the water and become wetted and somewhat washed. The 

 sand was very well-graded with a median diameter (determined by sieving) of 

 0.22 mm and a fall speed of 3.3 cm/sec. Some tree bark and other dark-col- 

 ored organic matter were contained in the sand. After extended periods of 

 wave action or when new sand was added to the beach profile, such as in the 

 construction of dunes, the water became cloudy and remained so until the tank 

 was drained and new water added. When the channel was drained, some 

 organic matter remained on the sand surface and was removed. 



Waves were run in intervals of, typically, 10, 20, 40, or 70 min. The 

 choice of these interval lengths was motivated by four considerations. First, 

 profile change produced by waves of the same characteristics normally pro- 

 ceeds rapidly at first and gradually slows as the profile assumes an equilibrium 

 shape. Therefore, the wave intervals were short at first and gradually 

 increased to record the change with profile surveys. Second, there was con- 



Chapter 1 Introduction to SUPERTANK 



