"no erosion" (L^/X < 0.8) was a reasonably good predictor of either accretion 

 or very little erosion. Gap erosion occurred for ratios of L /X greater 

 than 0.8. 



49. Berenguer and Enriquez' (1988) and Ahrens ' formulae to predict gap 

 erosion (Equations 26 and 29, respectively) for pocket beaches were evaluated 

 using data from the two sites at Colonial Beach (headland structures) . Both 

 relationships are inversely proportional to the data (Berenguer and Enriquez: 

 J? = -0.99, Ahrens: R = -0.24) (Figure 14). 



Structure depth 



50. Hallermeier 's (1983) relationship for recommended structure depth 

 was evaluated using the recommended depth for salient formation (Equation 37) 

 for all sites except Colonial Beach, where the recommended depth for tombolo 

 formation (Equation 38) was used (Figure 15) . An excellent correlation 

 between depth at the structure and Hallermeier 's recommended depth exists for 

 all but the Lakeshore Park data, resulting in a correlation coefficient 



R = 0.55 . 



50 





LEGEND 



40 



+ CP, 



+ Berenguer and Enriquez (1988) / 

 □ Ahrens (personal communication 1989) 





CPj + 



CB: Central Beach /^ 



30 



CPiCastlewood Park y^ 





CPj -+ 



/ DCB, 



20 



DCP, 



X 



10 



CPjD 



y/"^ PERFECT AGREEMENT 









y D CBj 



x/D 



CB^+ + + 





/CP3 



CB, CB^3 



10 

 on 



1 1 



n D CB3 



CB 



1 1 1 1 1 



Measured, m 



Figure 14. Evaluation of Berenguer and Enriquez' (1988) and 

 Ahrens' relationships for pocket beach gap erosion 



33 



