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



GIVEN : The average offshore slope Is 1/100 and T s = 8.0 seconds. 



FIND : The variation of significant wave heights at d = 1.50 meters for various 

 offshore wave steepnesses assuming no refraction effects. 



SOLUTION : L = 1.56 t| = 99.8 meters and from Figure C-l (App. C) for a slope 

 of 1 on 100 and d/L = 1 .5/ (1.56 (8) 2 ) = 0.015, the following values of H s /d 

 and H s are obtained for selected values of H^/L^: 



H 



Cm) 



0.5 



d 



H s 



at 



d swl = 

 Cm) 



1.5 m 



0.005 



0.5 







0.8 





0.01 



1.0 



0.66 







1.0 





0.02 



2.0 



0.73 







1.1 





0.04 



4.0 



0.77 







1.2 





0.08 



8.0 



0.85 







1.3 





Depth-limited breaking is important in this example for the larger waves, so 

 that as deepwater height increases from 0.5 to 8.0 meters, the nearshore height 

 only increases from 0.8 to 1.3 meters in a 1.5-meter water depth. 



*************** EXAMPLE PROBLEM 3 * ************** 



GIVEN : A wave gage in 4.0-meter Stillwater depth measured a significant wave 

 height of 2.0 meters with T s = 7.6 seconds. The nearshore bottom slope was 

 m = 1/50. 



FIND: The significant wave height at a second location with a Stillwater depth 

 of 1.0 meter. 



SOLUTION: For these conditions at location 1, 



^) =14=0.50 

 d ,*! 4.0 



m 



d T \ = i ^T= 0.007 



2 I (9.8 x 7.6 2 ) 



At location 2, 



(*).- 



1.0 



(9.8 x 7.6 2 ) 



0.0018 



To find the significant wave height at location 2, enter Figure C-2 (m = 1/50) 

 for (d/gT 2 )x = 0.007 and find the tL3/gT 2 where (H s /d) 2 = 0.50. In this case 



17 



