schematic profile shapes identified by Sunamura and Horikawa (1975). Their 

 classification is also similar to the two mentioned above. 



320. A factor that may influence profile development and net transport 

 rate distribution is the limited depth in the horizontal section of the tanks 

 in the CE and CRIEPI experiments. The effect is judged to be relatively minor 

 since the depth in the horizontal section was at least 2-3 times the wave 

 height in that part of the tank. Nevertheless, it is probable that some 

 amount of onshore transport would have occurred if the depth and movable 

 bottom had not been limited for those cases having transport distribution 

 Type E. In any case, such a contribution would probably be small compared to 

 the amount of material eroded from the foreshore. 



321. Aubrey (1979) studied long-term exchange of material across the 

 profile in the field. He applied empirical eigenf unction analysis to deter- 

 mine characteristic bar and berm profiles (prevalent during the winter and 

 summer, respectively) and discovered two pivotal points where the profile 

 depth was effectively constant. One pivotal point occurred for the studied 

 beach at 2 to 3-m depth and the second one at 6-m depth below mean sea level. 

 The seasonal volume exchange over the two pivotal points had a relation of 1 

 to 5, with the largest exchange taking place over the pivotal point closest to 

 shore. This occurrence indicates that, in a long-term perspective during 

 which weak onshore movement of sand may give a finite contribution, material 

 exchange in deeper water is much less than that in the nearshore. For a 

 single storm event giving rise to bar formation simulated in the LWT experi- 

 ments, the ratio between the sand transport rate from the seaward and shore- 

 ward sides of the bar should be small. 



Approach to Equilibrium 



322. As a beach profile approaches an equilibrium shape dictated by the 

 incident waves, the net cross-shore transport rate decreases to approach zero 

 at all points along the profile. By studying a relevant quantity related to 

 the transport rate distribution at consecutive times, a picture of the 

 approach to equilibrium can be attained. The peak onshore or offshore 

 transport rate along the profile is a candidate quantity which might be 



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