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 and through the 

 water column. 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 the 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 the local environmental 

 conditions must be known to calculate cross -shore and vertical distributions. 



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

 sand transport rate to obtain cross -shore and vertical distributions, in 1985 

 the Surf Zone Sediment Transport Processes Research Work Unit, under the Shore 

 Protection and Restoration Program at the Coastal Engineering Research Center 

 (CERC) of the US Army Engineer Waterways Experiment 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. Measurements were planned for beaches with transport influ- 

 enced by coastal engineering activities, such as near structures or beach 

 fills, as well as on beaches that have not been disturbed by engineering 

 activities. This report describes results of the first field data collection 

 project in the planned series. The experiment was originally intended as a 

 test of a newly developed sand trap and associated field data collection 



