5 Summary 



Nummedal and Snedden (1987) state that during storms and post-storm 

 recovery, large quantities of sand move in cross-shore directions. Large 

 quantities of this sediment may be lost from the beach and from the active 

 profile, thus necessitating beach fill. Much is known about nearshore sedi- 

 ment movement under shoaling waves (Komar 1976); precise documenta- 

 tion of cyclic patterns of surf-zone change (Wright et al. 1979, Nummedal 

 and Snedden 1987), and the well-studied effects of rip currents (Cook and 

 Gorsline 1972, Wright and Short 1984). 



However, despite undergoing intense study by geologists and engineers 

 for over a century, there are still many fundamental, unanswered questions 

 about patterns, mechanisms, and rates of beach-shelf sediment inter- 

 change. An extensive amount of field work concerning contrasting inner 

 shelf environments is needed (particularly data from cross-shore arrays 

 which provide simultaneous measurements at different depths of near- 

 bottom flows, sediment fluxes, and bed responses). Wright (1987) 

 believes that in determining cross-shore inner shelf sediment transport 

 processes, attention should be placed on field studies and modeling the 

 naturally occurring inner shelf environments. Wright (1987) believes that 

 no one model (or concept) effectively describes inner shelf transport. 



Nummedal and Snedden (1987), Wright et al. (1991), and Pilkey (1993) 

 contend that existing models of equilibrium profile development and cross- 

 shore sediment transport are seriously inadequate. 



Pilkey et al. (1993) contend that present-day assumptions of the profile 

 of equilibrium concept indicate the following: 



a. Sediment movement on the inner shelf is an exceedingly complex 

 phenomenon driven by a wide range of wave, tidal, and gravity 

 currents. 



b. The depth of closure does not exist, as evidence shows that large 

 volumes of sand may frequently be moved beyond the depth of 

 closure. These large volumes of sediment moved are often spread 

 over such a large area that standard profiling methods cannot detect 

 this movement. 



Chapter 5 Summary 



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