where Q^ is the volume at final equilibrium state, equal to 2,100,000 cu 

 yd** for the Santa Monica breakwater and A is an empirical coefficient, 

 determined as 0.104 year"^. The authors conclude that, without dredging 

 events, the Santa Monica breakwater would have reached 90-percent growth in 

 22 years. 

 Silvester and Ho (1972) 



40. For beaches that have equilibrated with headland structures, 

 Silvester and Ho (1972) present a relationship to predict the maximum gap 

 indention (X + X^) given a gap distance Lg and predominant wave direction 

 /3 (degrees) (Figure 9). 



Japanese Ministry of Construction (1986) 



41. The empirical method of breakwater design described by the JMC in 

 their "Handbook of Offshore Breakwater Design" (1986) has several advantages 

 over the empirical relationships presented previously. The JMC method is a 

 step-by- step iterative procedure, allowing the designer to follow specific 



0.7 



0.6 



^ 0.5 



!> 0.4 



O) 

 X 



+ 0.3 

 •2S 0.2 



.1 

 





— L 







1 FfiFMn 





1 



9 ^ 









/???//?X 



• VICHETPAN EXP. 



o HO EXP. 



X PROTOTYPE BAYS 



■ TYPICAL BAY 



A BEDOCK SINGAPORE 





























• 



• 



• 











od^ 



ojx^^-^ 



E 



• 











( 



>^ ' %. 













.-' 

































^ 



















10 20 30 40 50 60 70 80 



PREDOMINANT WAVE DIRECTION /3' 



90 



Figure 9. Relationship to predict gap erosion for headland 

 structures (after Silvester and Ho 1972) 



To convert cubic yards into cubic metres, multiply by 0.7645549. 



26 



