Sand Transport Measurement Methods 



6. In preparation for the first field data collection project, DUCK85, 

 Kraus (1987) surveyed available sand transport measurement methods (tracer, 

 impoundment, and traps) and concluded that traps offered the best means to 

 obtain transport rate data compatible with the accuracy and detail required by 

 existing numerical models which simulate beach evolution. Traps were also 

 determined to be the least expensive of the three methods. 



7. Portable traps allow measurement of the vertical distribution of the 

 transport rate (transport at the bed and through the water column) , and simul- 

 taneous deployment of traps at intervals across the surf zone enables measure- 

 ment of the cross -shore distribution of the longshore transport rate. Traps 

 can also be repeatedly deployed at one or two points in the surf zone to 

 obtain temporal variations of the sand transport rate. Traps measure the sand 

 flux, a quantity directly related to the transport rate, and not simply a 

 sediment concentration. As in concentration measurements, transported par- 

 ticles are automatically retained by the traps and made available for analy- 

 sis. Traps collect the material that actually moves, including sand, shell 

 fragments, and other particles of size nominally larger than the trap mesh, 

 and no assumptions need be made about grain size, as required in tracer 

 studies. Mean wave and current conditions in the surf zone typically change 

 on the order of minutes, and traps are well suited to such a sampling interval 

 as opposed to tracer and impoundment methods. Traps are also inexpensive to 

 construct and maintain, and only a minimum amount of training is necessary to 

 use them. Disadvantages of traps include the potential for scour and, in surf 

 zones, restriction to use with significant breaking wave heights on the order 

 of 1 m or less. 



SUPERDUCK Field Data Collection Project 



8. During September and October 1986, CERC hosted and participated in a 

 major multidisciplinary and multi-institutional nearshore processes field data 

 collection project called SUPERDUCK. The name SUPERDUCK derives from the 

 location of CERC's Field Research Facility (FRF), the site of the experiment, 

 which is located near the village of Duck, North Carolina, on the Outer Banks 



