and 



gives 



H' 



— r- = 0.00637 



m = 0.05 



or 





H^, = 10.35 m 



From Figure 3-50, with Hj, = 10.35 meters 



%_ 

 81^ 



= 0.007327 



and 



gives 



m = 0.05 



rj- = 0.123 



or 



S^ = 1.27 m 



Therefore, the mean water level will be at elevation +5.87 meters which is 

 0.23 meter below the top of dunes. Extensive flooding should be expected as 

 wave runup will overtop the dune crest, thus eroding it to a lower elevation 

 and allowing continuous overflow. 



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



b. Wave Setup Due to Random Waves . Random wave setup produced by local 

 storm waves (sea) may be somewhat different from the mean water level produced 

 by monochromatic waves( swell) discussed in Chapter 3, Section VIII, 5. Under 

 sea conditions, groups of large waves may pump significant quantities of water 

 toward the shoreline to cause setup, but some of this water can flow seaward 

 during the relatively calm intervals between wave groups. 



Let S be the mean water level position above the Stillwater level (S is 



3-106 



