[h 1 = H K^ = 1.0(0.295) = 0.30 m (1.0 ft) 

 ^ s ' t s To 



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



Note that equation (7-17) gives conservative estimates of K„ for F = 

 with the predicted values of the transmission coefficient corresponding to the 

 case when the magnitude of the incident wave height is very small. Observed 

 transmission coefficients for F = are generally smaller than predicted, 

 with transmission coefficients a weak function of wave steepness as 

 illustrated by the example in Figure 7-43. 



Wave runup values in equation (7-17) and for use with Figures 7-39, 7-40, 

 7-41, and 7-42 can be determined from Section 11,1, Wave Runup. Runup for 

 rough impermeable and permeable breakwaters can be estimated from Figure 

 7-44. The "riprap" curve should be used for highly impermeable rough struc- 

 tures and to obtain conservative estimates for breakwaters. The other curves, 

 such as the one from Hudson (1958), are more typical for rubble-mound 

 permeable breakwaters. 



Note that for wave transmission by overtopping of subaerial breakwaters, 

 the transmission becomes more efficient as the incident wave height increases 

 (all other factors remaining constant) until K^^ reaches a uniform value 

 (Figure 7-45). This is the opposite of the trend observed for a submerged 

 breakwater (Figure 7-37). Figure 7-46 summarizes the transmission and 

 reflection coefficients for a smooth impermeable breakwater, both submerged 

 (d /h > 1) and subaerial (d /h < 1) . Some examples of transmission for 

 rough impermeable breakwaters are shown in Figures 7-47 and 7-48. 



*************** EXAMPLE PROBLEM 13 



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



FIND: 



The wave transmission by overtopping coefficient for a rough 



impermeable breakwater having the following characteristics; 



7-73 



