SOLUTION ; 



(a) The previous example problem in Section II, 2, a gives a solution for the 

 overtopping rate of a 1.5-m (4.9-ft) significant wave corrected for the 

 given wind effects as 



3 

 Q = 0.5 m /s-m 



(b) For the value of a = 0.08 given in the previous example problem, the 

 value of Qq qqc is determined as follows : 



Rg = 5.1 m (16.7 ft) from previous example problem 



h-d. 



s 1.5 



Rg 5.1 



= 0.294 



From the upper curves in Figure 7-35, using a = 0.08 and (h-d )/R 



o 6 



= 0.294 



^0.005 



= 1.38 



Qq qq^ = 1.38 (0.5) = 0.7 m^/s-m (7.4 ft^/s-ft) 



(c) From the lower set of curves in Figure 7-35, using a = 0.08 and 

 (h-cfe)/lfe = 0.294 , 



4= 0.515 



Q = 0.515 (0.5) = 0.3 m^/s-m (3.2 ft^^/s-ft) 



The total volume of water overtopping the structure is obtained by 

 multiplying Q by the length of the structure and by the duration of the 

 given wave conditons. 



*************************************** 

 3. Wave Transmission . 



a. General . When waves strike a breakwater, wave energy will be either 

 reflected from, dissipated on, or transmitted through or over the structure. 

 The way incident wave energy is partitioned between reflection, dissipation, 

 and transmission depends on incident wave characteristics (period, height, and 

 water depth), breakwater type (rubble or smooth-faced, permeable or imper- 

 meable), and the geometry of the structure (slope, crest elevation relative to 

 SWL, and crest width). Ideally, harbor breakwaters should reflect or 

 dissipate any wave energy approaching the harbor (see Ch. 2, Sec. V, Wave 



7-61 



