The designer is cautioned, however, not to confuse the wave setup with 

 wave runup. If an estimate of the highest elevation reached by wave runup on 

 the shore is desired, the runup produced by a larger design wave can be 

 estimated after considering the water level produced by wave setup (using 

 H ) and other effects (astronomical tide, wind setup, etc.)» The selection 



of a design wave for runup considerations is left to the designer, based on 

 the requirements of the project. 



The wave setup estimates using the methods described in this section are 

 based on the assumption that the waves approach normal to the coast. A wave 

 that approaches the coast at an angle has components normal and parallel to 

 the coast. The normal component produces wave setup; the parallel component 

 produces a longshore current. It is reasonable to assume that the setup is a 

 function of the cosine of the angle between the wave crest at breaking and the 

 shore. Reducing the estimated wave setup in this manner is left to the 

 judgment of the designer. 



*************** EXAMPLE PROBLEM 9*************** 



GIVEN: A wave gage is located in 7 meters of water at mean low water. An 

 analysis of the gage record for a period during a storm yields a signifi- 

 cant wave height H = 6 meters and period Tg = 12 seconds . 



Assume the direction of wave approach is normal to the coast which has 

 straight and parallel depth contours (i.e., refraction coefficient = 1.0). 



FIND: The maximum water level at the beach for which runup calculations 

 can be made considering an initial Stillwater level at mean low water. 



SOLUTION : From the given conditions (shown in Figure 3-51) it is clear that 

 the significant wave will break offshore of the shelf and induce a setup. 

 First, define the unrefracted deepwater wave height H' and the breaker 

 height Hj, . From Table C-1, Appendix C, 



d 



and 



L 2 



o 1.56 (12 ) 



4- = 1.118 

 "0 



H^ = 5.37 m 



= 0.0311 



From Figure 7-3 where m = 0.05 and H^gT = 0.00380 

 H, 



which gives 



H^ = 7.03 meters 



3-104 



