^o = C(l -|)= 0.44 (l-f^) =0.257 



The transmitted wave height is: 



Ht = Kto Hi = 0.257 (9) = 2.3 feet (0.71 meter) 



*************** EXAMPLE PROBLEM 2*************** 



GIVEN ; A vertical, smooth-faced impermeable breakwater with a crest width of 

 12.0 feet (3.7 meters), a structure height of 16.0 feet (4.9 meters), and a 

 water depth of 11.2 feet (3.4 meters) as shown in Figure 2(a). 



FIND : Transmitted wave height for an incident monochromatic wave with a period 

 of 12.0 seconds and height of 6.0 feet (1.8 meters). 



SOLUTION : From equation (4) the runup is 



/ OOL i\(0.228 v/6/11.2 + 0.0578) 

 R = 6 (0.958) (0.123 \ ) = 8.1 feet (2.5 meters) 



From equation (2) 



and the breakwater freeboard is 



F = h - dg = 16.0 - 11.2 = 4.8 feet (1.5 meters) 

 From equation (1) the transmission by overtopping coefficient is 



%o = C (l- I) =0.43 (l-|^)= 0.175 



and the transmitted wave height is 



Ht = Kxo H = 0.175 X 6.0 = 1.0 foot (0.32 meter) 



Figure 2(b) shows how the predicted transmitted wave height varies as a func- 

 tion of incident wave height and period for this example breakwater. 



V. SUMMARY 



Methods of predicting transmission coefficients of impermeable breakwaters 

 show that the magnitude of the transmission coefficients is a function of the 

 breakwater freeboard, incident wave height and period, water depth, and struc- 

 ture slope, crest width and roughness. Calculations may be performed manually 

 or with the FORTRAN computer program OVER (Program No. 752XR1CYO) available 

 from the CERC ADP Coordinator, U.S. Army Coastal Engineering Research Center, 

 Fort Belvoir, Virginia 22060, 



