detached breakwater gap spacing on sand entrapment. Relationships for the 

 average quantity of sand deposited to the lee of each breakwater, Q^, , both 

 to the lee of the breakwater and in the gap area, (Q^^ + Q^) , and in the gap 

 area alone are presented in Figures 6 through 8. Combining model results with 

 prototype data, Harris and Herbich relate the dimensionless accreted volume to 

 structure parameters as follows: 



0.31 - 1.92( 



X L, d 



(45) 



The relationship is based on data with values of X/L^ ranging from . 5 to 



2.5. 



Sonu and Warwar (1987) 



39. Sonu and Warwar (1987) empirically relate the growth of the Santa 

 Monica, CA, tombolo through time as follows: 



i? = £)„ (1 - e-^"^) (46) 



0.4 I— 



0.3 



0.2 



.1 



LEGEND 



O Lg/Ls= 0.25 



A Lg/Ls= 0.50 



D Lg/Ls= 1.00 



0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 



Figure 6. Effect of gap spacing on sand deposition 

 to lee of breakwater (after Harris and Herbich 1986) 



24 



