From Figure 3-50, where H^ = 7.03 , H^/gT"^ = 0.004976 and m = 0.05 

 S 



w 



H, 



= 0.111 



or 



S,, = 0.78 m 



0.3 meter MLW 



Figure 3-51. Definition sketch 



Therefore, the hew water level at the beach will be 0.78 meter at mean low 

 water, which will result in a depth of 1.08 meters (3.6 feet) at the toe of 

 the beach slope. The computation of the maximum runup height on the beach 

 would involve the determination of the maximum breaking wave and run up for 

 a range of wave periods. The highest runup elevation computed would be used 

 for design purposes. 



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



*************** EXAMPLE PROBLEM 10*************** 



GIVEN : A mathematical model simulation indicates that a particular section 

 of coastline will experience a storm surge of +4.6 meters for a par- 

 ticular hurricane. The backshore area is protected by a continuous line 

 of sand dunes whose lowest elevation is at about +6.1 meters. The 

 estimated deepwater significant wave height and period are H^ = 9 

 meters and T„ = 12 seconds . The beach slope is a constant m = 0.05 



T„ = 12 seconds 

 s 



FIND: 



Whether continuous flooding of the backshore can be expected when 



wave setup is considered. 



SOLUTION : 



First, assume that H^ = H' in this case. 



o 



Then 



found from Figure 7-3. With 



Hij can be 



3-105 



