40 



20 



-20 



- 





□ LV, 



D 



LV 2 



DLV 3 





- 









CB,D/MD 



^/ CS 2.3.4 







PERFECT — \ 

 AGREEMENT 





LEGEND 



- 



LS ' D n dls 3 



LS 2 



CP 2 / 



cp ' D /dcp, 





CB: Central Beach 

 CP: Castlewood Park 

 LS: Lakeshore Park 

 LV: Lakeview Park 



1 1 



II 



-20 



20 40 



X s , Measured, m 



Figure 25. Evaluation of Suh and Dalrymple's (1987) relationship for salient length (from 

 Rosati (1990)) 



0.8 <, — £ <, 1.3 possible erosion opposite gap 



(7) 



J ^ 1.3 certain erosion opposite gap 



(8) 



These relationships were evaluated with prototype data (Figure 26). The 

 lower boundary for no erosion {L g /X < 0.8) was a good predictor of either 

 accretion or very little erosion. Gap erosion occurred for ratios of L^X 

 greater than 0.8. 



Structure depth. Hallermeier (1983) recommends the following water 

 depth as a guide for positioning detached breakwaters when tombolo formation 

 is deemed undesirable: 



d„„ = 



2.9//„ 



110// 



l/(^~T) (S-l)gr e 



i — depth for salient formation 



(9) 



Chapter 2 Functional Design Guidance 



43 



