transition from one breaker type to another is gradual without distinct divid- 

 ing lines; however, Patrick and Wiegel (1955) presented ranges of H'/L for 

 several beach slopes for which each type of breaker can be expected to occur. 

 This information is also presented in Figure 2-72 in the form of three regions 

 on the H^/H^I, vs H'/L^ plane. An example illustrating the estimation of 

 breaker parameters follows. 



*************** EXAMPLE PROBLEM 18*************** 



GIVEN : A beach having a 1 on 20 slope; a wave with deepwater height H = 2 

 meters (6.56 ft) and a period T = 10 seconds. Assume that a refraction 

 analysis gives a refraction coefficient K^ = (h^/h)^^^ = 1.05 at the point 

 where breaking is expected to occur. 



FIND ; The breaker height H^ and the depth d^^ at which breaking occurs. 



SOLUTION ; The unrefracted deepwater height H' can be found from 



H' /b \l/2 



hence , 



and, 



H^ = 1.05(2) = 2.10 m (6.89 ft) 



H' 



o 2.10 



— T = : T = 0.00214 



gT^^ 9.8(10)2 



, 2 

 From Figure 2-72 entering with H^/gT = 0.00214 and intersecting the curve for 



a slope of 1:20 (m = 0.05) result in %/H^ = 1.50. Therefore, 



E^ = 1.50(2.10) = 3.15 m (10.33 ft) 



To determine the depth at breaking, calculate 



^ ^'^^ = 0.00321 



gT^ 9.8(10)' 



and enter Figure 2-73 for m = 0.050. 



d 





2-135 



