control check on trap operation and early interpretation of results for 

 further experiment design. 



Transport Rate Analysis 



28. The procedures for calculating transport rates from the raw data 

 are described in this section. As opposed to instantaneous samplers, pumps, 

 and acoustic or optical sensors which measure sand concentration, the 

 streamers measure a sand flux, i.e., the weight of sand passing through the 

 nozzle of a certain cross-sectional area in the sampling interval. If the 

 sampling is performed in a unidirectional flow, as was the case in these 

 experiments, no sand is lost once it has entered the streamer, and the flux 

 can be directly associated with the current to develop predictive empirical 

 relations. The raw data of sand weight collected in the streamers are listed 

 in Table Al of Appendix A. 



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



S(k) 



in which 



F = sand flux (kg/(m^-sec) ) 



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



to the last streamer (k = N) 

 S = dry weight of sand (kg) 

 Ah = height of streamer nozzle (0.09 m for DUCK85) 

 Aw = width of streamer nozzle (0.15 m for DUCK85) 

 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) 



23 



