and spaced vertically on 0.3-m centers over the entire depth. The stations 

 were numbered with Station 1 at x = 0.3 m (location of the more seaward of 

 the inserts in each pair where the wave gauges and current meters were 

 mounted) and station numbers increasing at 3.7-m intervals offshore. 

 Figure 1-3 shows the channel layout including stations. 



SUPERTANK is believed to be the most densely and comprehensively 

 instrumented nearshore processes data collection project conducted in the 

 laboratory or field. At the peak of data collection activities, the LWT channel 

 was instrumented with 16 resistance wave gauges, 10 capacitance wave gaug- 

 es, 18 two-component electromagnetic current meters, 34 optical backscatter 

 sensors (OBS), 10 pore-pressure gauges, 3 acoustic sediment concentration 

 profilers, 1 acoustic Doppler current profiler, 1 four-ring acoustic benthic 

 stress gauge, 1 LDV, 5 video cameras, and 2 underwater video cameras. The 

 resistance wave gauges, capacitance wave gauges, and electromagnetic current 

 meters formed the core of SUPERTANK data collection and were maintained 

 throughout the project. Synchronous sampling by separate data acquisition 

 systems was accomplished by digital input of a WWV time code (broadcast by 

 National Institute of Standards and Technology, Fort Collins, CO, call letters 

 WWV) to all computer clocks. 



Core Measurements 



Core measurements constitute data collection fundamental to all investiga- 

 tors. The core measurements consist of wave and current data collection and 

 beach profile surveys. CERC investigators were responsible for these mea- 

 surements. 



Waves and currents 



Water surface elevation was measured with 16 resistance wave gauges 

 mounted on the west channel wall (left side of LWT in Figure 1-2), spaced 



3.7 m (12 ft) apart. The array of resistance gauges extended from near the 

 wave generator to a water depth of approximately 0.5 m. An array of 10 

 capacitance wave gauges extended from the most shoreward resistance gauge 

 to the maximum runup limit. These gauges were also mounted from the west 

 channel wall, but they were mobile with spacing that varied from 0.6 to 



1.8 m. In addition to measuring wave transformation, the capacitance gauges 

 also measured runup and the elevation of the sand surface at gauges that were 

 intermittently submerged (Figure 1-4). 



Fourteen Marsh-McBirney electromagnetic current meters were mounted 

 on the east channel wall together with arrays of OBS (Figure 1-5). The cur- 

 rent meters were deployed in vertical arrays of one to four sensors with verti- 

 cal spacing of approximately 0.3 m, designed to quantify the undertow pro- 

 file. Each array was configured to share a timing pulse (close-proximity 



Chapter 1 Introduction to SUPERTANK 



