at various water depths, wave heights, and wave periods and found that the 

 ponding level (Fig. 3) may be estimated from 



|r - 0.6e "(-°- 7 * kJ 



= 0.1 for ~ > 2.05 

 ^o 



(3) 



where F is the breakwater freeboard defined as (h - d s ) . The maximum ponding 

 level occurs at F/Hq = 0.7 because this is the point just before the seaward 

 flow over the top of the breakwater occurs. Note that there is scatter in the 

 data used to develop equation (3) with approximately 90 percent of all data 

 points falling within 20 percent of the equation. A sensitivity analysis shows 

 that this scatter is not important for this report, because flow rates are 

 weakly influenced by the value of P. 



Note that the laboratory tests used to develop equation C2) show some 

 ponding for high breakwaters not overtopped and submerged breakwaters. This 

 ponding occurs because the breakwater reduces the wave height landward of the 

 structure and the change in wave height causes wave setup (Longuet-Higgins, 

 1967) . 



Overtopping tests by Diskin, Vajda, and Amir (1970) show that the net over- 

 topping rate, q n , for breakwaters may be estimated from 



In = <lo 



(-W 



(4) 



0.8 

 0.7 

 0.6 

 0.5 

 P/Hj, 0.4 

 0.3 

 0.2 

 0.1 

 











1 1 " . 8 



P/H =0.6e-<-°- 7 + F/H °> 























^^^ 



V 

















P/H o ~0.l 



fnr 













F/Hq>2.05 















\ 















, 1 

















-1.0 



0.5 







1.5 



2.0 



0.5 1.0 



Figure 3. Ponding levels for porous multilayered breakwaters (after 

 Diskin, Vajda, and Amir, 1970). 



12 



2.5 



