INCIDENT WAVES 



BREAKING WAVES 



CURRENT METERS 



TRAPS 



PHOTOPOLES 



LONGSHORE CURRENT 



BEACH 



BASE CAMP 

 Figure 5 . Typical arrangement for field experiment 



currents, streamers tend to wrap around the rack, reducing the effective 

 length to approximately 38 cm (the width of the rack). The trap operators 

 then unwrap and, as necessary, untwist the streamers to allow them to extend 

 freely in the flow. 



21. At the end of the sampling period, the operators lift the traps out 

 of the water and carry them to shore. Most of the collected sand is located 

 at the end of the streamers, although some particles may cling to the sides. 

 The streamers are removed from the rack, and sand clinging on the sides of the 

 cloth is washed to the end by holding the nozzle upright and dipping the tied 

 streamer into a large (for example, 110-liter) barrel filled with seawater . 

 The streamer end can then be untied and the collected sand washed into a patch 

 of sieve cloth which had previously been weighed when wet. Alternatively, the 

 sample can be washed into a collection bag and taken to the laboratory for 

 weighing and analysis. 



17 



