A (J /3 ) 



I ii i il 

 0.1 



I I I I I I l ll 



i l i l l i i i I 



1.0 10.0 100.0 



Sediment Diameter (mm) 



Figure 8. Shape factor A versus sediment diameter 

 (Moore 1982) 



32. The equilibrium profile concept is useful for two purposes: it 

 provides a convenient means of visualizing the process of profile change; 

 and, through Equation 1, it provides a reasonable description of the general 

 shape of the beach profile. 



Natural Variation in Measured Profiles 



33. As already mentioned, the beach profile is in constant motion 

 under the imposed hydraulic forces which move sediment across and along the 

 shore. The profile thereby undergoes notable short-term macroscale changes 

 (order of days and tens of cubic meters) apart from seasonal and long-term 

 changes. On real and laboratory beaches, these changes do not have perfect 

 symmetry alongshore; there is always some degree of three-dimensionality. 

 This longshore variability may result from the presence of shore protection 

 structures such as jetties or groins, or the variation may be naturally 

 generated by the hydraulic conditions (e.g., by beach cusps or rip currents). 

 Varying geological characteristics along the coast will also produce markedly 



17 



