27. The flux of sand F at streamer k is given by 



Flk) = .?<*> CD 



AhAwA t 



in which 



F = sand flux, kg/ (m 2 - sec) 



k = streamer number, increasing in order from the bottom (k = 1) 

 to the last streamer (k = N) 



S = dry weight of sand, kg (force) 



Ah = height of streamer nozzle (0.025 m for SUPERDUCK) 



Aw = width of streamer nozzle (0.15 m for SUPERDUCK) 



At = sampling time interval, sec 



The flux between adjacent streamers FE(k) can be estimated by linear 

 interpolation using adjacent measured values 



FE(k) = 0.5 [F{k) + F(k+1)] (2) 



28 . The total transport rate per unit width i at a particular trap is 

 calculated by using the determined fluxes and distances Aa(k) between 

 nozzles , 



i = Ah £ F(k) + £ Aa(k)FE(k) ( 3 ) 



in which N is the total number of streamers on the trap. The first summa- 

 tion term represents the actual measured fluxes, and the second summation term 

 represents the interpolated fluxes between nozzles . If traps were placed on a 

 line across the surf zone (SSM) , transport rates per unit width were calcu- 

 lated with Equation 3, and the trapezoid rule was used to compute the total 

 longshore sand transport rate across the surf zone. Elevations of the 

 streamers above the bed are listed in Table A2 of Appendix A. 



29. Sand-trapping efficiency tests in uniform flow were performed in a 

 series of experiments (Rosati and Kraus 1989) for nozzle configurations which 

 had near-optimal hydraulic efficiencies (Rosati and Kraus 1988) , including the 

 DUCK85 and SUPERDUCK nozzles. It was found that the SUPERDUCK nozzle had a 



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