waves, currents, and beach change. Beach morphology response models are 

 moving from the research level to the practical level as engineering design 

 tools. A requirement in making this transition is improved capability for 

 predicting the longshore sand transport rate , not only the total longshore 

 transport rate but also its distribution across the surf zone, through the 

 water column and its variation with time. For example, these distributions 

 are needed for estimating bypassing around, over, and through groins and 

 jetties and behind detached breakwaters. 



4. Presently available predictive formulas for the longshore sand 

 transport rate are generally acknowledged as providing only a rough approxima- 

 tion of the actual rate. The number of accepted field measurements comprising 

 the data base is surprisingly small considering the importance of the problem, 

 and scatter in the data is great, reflecting randomness in the physical 

 processes, limitations in measurement techniques, and simplifications in 

 predictive expressions used to describe fluid and sand motion. Presently 

 employed predictive formulas for the transport rate do not incorporate 

 dependencies on grain size, breaking wave type or wave -induced turbulence, 

 properties of the waves or longshore current beyond mean values , or influence 

 of the local bottom shape. The transport rate is expected to greatly depend 

 on location in the surf zone, and its dependency on local conditions must be 

 known to calculate cross -shore and vertical distributions. 



5. Recognizing the need for point measurements of the longshore sand 

 transport rate to obtain cross-shore and vertical distributions, the Surf Zone 

 Sediment Transport Processes Research Work Unit was begun in 1985. This work 

 unit, under the Shore Protection and Restoration Program at the Coastal 

 Engineering Research Center (CERC) of the US Army Engineer Waterways Experi- 

 ment Station, initiated a series of field experiments aimed at collecting 

 comprehensive data sets on sand transport and processes responsible for the 

 sand movement. Field data collection was planned for beaches composed of 

 different materials ranging from fine sand to gravel and for wave climates 

 ranging from small to large wave steepness. This report describes the results 

 of the SUPERDUCK experiment, the second field data collection project in the 

 planned series . 



