A composite analysis of all sediment samples collected between sta 246 and 
276 resulted in a Q<o of 0.65 (ds) = 0.64 mm) and a standard deviation of 0.770. 
If the typical lognormal grain-size distribution of sediments is assumed for the 
beach-fill material, a 95-percent confidence interval for the @., is defined by the 
range of @ units within two standard deviations of the mean. For the samples 
taken from the beach fill, the range of ,, defining the 95-percent confidence 
interval is 2.20 to -0.89, which corresponds to a range from ds, of 0.22 to 
1.86 mm. The sieve analysis is presented in Appendix B. 
Profile comparisons 
Based upon the statistical definitions from the sieve analysis, equilibrium 
profiles computed from the median grain size and the bounds of the 95-percent 
confidence interval were compared with the October 1995 profiles. The com- 
parisons of the measured profiles with the equilibrium profiles give an indication 
of each profile’s equilibrium status. Profiles on the steep side of the mean 
equilibrium profile are expected to adjust in the cross shore to come closer to 
equilibrium. Beach profiles that are near equilibrium are not to be expected to 
adjust substantially in the cross-shore direction. 
In the region between sta 255 and 295, beach profiles are near their 
equilibrium shape. Figure 23 shows the beach profile at sta 275 with the 
corresponding equilibrium profiles for median grain diameters of 0.22, 0.64, and 
1.86 mm. It is evident in this figure that the beach profile at sta 275 is ina 
similar shape as the equilibrium beach profile for the average d., from the sieve 
analysis. Significant shoreline recession because of cross-shore adjustment of 
this profile is not expected. 
In contrast to the profiles of the hot-spot region, the beach profiles between 
sta 208 and 255 do not indicate an approach to equilibrium beach profile shape. 
Instead, the beach profiles tend to be steeper than equilibrium, indicating that 
cross-shore profile adjustment and related shoreline recession is expected in this 
region. Figure 24 illustrates the typical relationship between measured and 
equilibrium beach profiles immediately north of the hot-spot region (October 
1995). In this figure, the beach profile for sta 240 is shown to be considerably 
steeper than the 0.64-mm equilibrium beach profile. Neglecting additional 
longshore transport processes, this beach profile’s shape will adjust to become 
closer to the shape of the equilibrium beach profile. As a consequence of this 
cross-shore adjustment, a corresponding recession of the shoreline position is 
expected. Shoreline recession because of cross-shore adjustment is not expected 
to exceed the anticipated adjustment from the project design. 
Chapter 3 Beach Profile Evolution 
27 
