22. Recognizing a need for more accurate prediction of sand transport 

 at a point as a function of waves and currents at that position, a Temporal 

 Sampling Method (TSM) was used during the SUPERDUCK experiment. In the TSM, 

 one or two traps were repeatedly deployed at one or two points in the surf 

 zone, with corresponding wave and current measurements made in the same 

 region. If two traps were deployed in close proximity (about 1 m apart) , an 

 indication of reliability between two traps under similar hydrodynamic 

 conditions was obtained, termed a "consistency test." The TSM runs resulted 

 in high-quality measurements of the sand transport rate as a function of local 

 waves and currents through time, at 5-min intervals for as long as an 84-min 

 data collection period. 



23. To measure the transport rate during a typical TSM run, two traps 

 (denoted by symbols Tl and T2 in Figure 2) were carried to predetermined 

 positions located updrift of current meters (denoted by symbols CM1 and CM2 in 

 Figure 2), and referenced to the photopole line. Usually one person carried 

 and operated one trap; however, two operators were necessary if surf zone 

 conditions were rough or if the traps were positioned at the breaker line. At 

 a signal, the racks were simultaneously thrust into the bed with the nozzles 

 oriented into the longshore current. Horizontal bars along the bottom of two 

 sides of the rack could be stepped on to bury the 40-cm-long legs. At 

 complete burial of the rack legs, the horizontal bars prevented further 

 penetration of the legs and kept the lowermost streamer nozzle at the bed. 

 During the course of a trap deployment (typically of 5- to 10-min duration), 

 the trap operator would periodically step on the horizontal bars to keep the 

 trap legs fully buried and to counter wave and current action, which would 

 tend to tilt the trap shoreward and downstream, respectively. In weak long- 

 shore currents, the streamers would wrap around the vertical bars of the rack 

 with passage of waves, requiring the trap operator to untangle them. In 

 moderate to strong currents (greater than approximately 20 cm/sec) , the 

 streamers would fully extend in the flow and require little attention from the 

 trap operator. Figure 9 shows the traps being deployed in a TSM run. 



24. At the end of the first sampling period, a signal was given from 

 the beach, and the two traps were pulled from the bed as the second set 

 (denoted by the symbols T3 and T4 in Figure 2) was deployed at approximately 

 the same locations in the surf zone. The first two traps were lifted above 



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