and from Figure 4 



§T- 0.88 

 and 



R = 0.88(1.52) = 1.34 meters (4.39 feet) 



As a check, the runup will be calculated using equation (8) . Assuming that 

 the toe of the structure is in a water depth of 17.24 meters (56.5 feet), the 

 required local wave height is the incident deepwater height of 1.52 meters. 



Using equation (8) with the best fit coefficients gives 

 R 0.956 



H 



0.398 + (1. 52/34. hi) 1 1 ^ (3.0) 



= 0.93 



and 



R = 0.93 x (1.52) = 1.41 meters (4.64 feet) 

 Using equation (8) with the ETL 1110-2-221 coefficients gives 



1 = Lfl -T7- 



and 



0.4 + (1.52/34.47) /2 (3.0) 



R = 0.97 x 1.52 = 1.47 meters (4.82 feet) 



Agreement among the three methods shown above is good, and since the 

 significant wave height was used in the computations the runup will be 

 referred to as the significant runup, R s . Since some waves will produce 

 runup greater than R s , one way to estimate the maximum runup, Rmax» 

 is to assume that the ratio of Rmax to Rs is the same as the ratio of 

 the maximum wave height at the toe of the structure, H max , to the sig- 

 nificant wave height at the toe of the structure, H s . For the deepwater 

 conditions of this example, Goda (1975) gives 



"max . , , 



— - — = 1.64 



where H^^x represents the average highest wave in a group of about 250 

 waves. For wave breaking in shallow water, the ratio of the maximum to sig- 

 nificant wave height is lower than shown above and can be calculated using 

 a model developed by Goda (illustrated in example 4) . The value H^^Hs = 

 1.64 is consistent with the limiting value for deep water in Goda's model. 

 Thus, the maximum runup for Stoa's method is 



( H max \ _ 

 h s ;- 



= Re; I -rr^ = 1.34(1.64) = 2.20 meters (7.22 feet) 



