at the site. In this case, cross -shore transport will determine the change in 

 beach profile contours. This assumption will be made in this investigation: 

 longshore sediment transport is neglected and profile change produced solely 

 by cross -shore sediment transport is considered. 



5. The ultimate goal of this investigation is development of a numeri- 

 cal model to predict beach profile change produced by wave action. Numerous 

 such models have been reported in the literature; however, apart from the 

 present work only one highly schematized numerical model has been considered 

 sufficiently accurate to be of engineering use. Most efforts appear to have 

 failed because the level of detail attempted was beyond the state of knowledge 

 of the physical processes involved. At present, knowledge is very limited on 

 the collective motion of sediment particles in spatially varying flows of 

 oscillatory currents, wave- induced mean current, and turbulence fields of 

 breaking waves. Numerous other complicating factors, such as the complex 

 fluid motion over an irregular bottom and absence of rigorous descriptions of 

 broken waves and sediment- sediment interaction, also make the problem of 

 computing sediment transport and resultant beach profile change essentially 

 impossible if a first-principles approach at the microscale is taken. 



6. On the other hand, despite the incredibly complex and diverse 

 processes and factors involved, beach profile change, if viewed on the macro - 

 scale (spatial scale on the order of meters, and temporal scale on the order 

 of hours), is remarkably smooth and simple. Certain prominent features, such 

 as bars, troughs, and berms go through cycles of formation, growth, movement, 

 and erasure with a morphodynamic pattern that has been reasonably well 

 described by a number of qualitative conceptual models. The question can then 

 be asked whether it is possible to develop a quantitative (numerical) model of 

 beach profile change based on empirically determined global relations for the 

 wave -induced net cross -shore sediment (sand) transport rate that can be 

 inferred from the smooth and regular change observed to occur during beach 

 profile evolution. Development of such a model is the subject of this 

 investigation. Consideration is limited to sediment in the sand range of 

 grain size (particle diameters in the range of 0.062 - 2.00 mm). 



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