_ ^ - ^ 



^ - o rr~ > (16) 



where H^ is the maximum stable wave height given by equation (15), H^ 

 the incident wave height at the seaward edge of the fetch segment, and 

 Hg^ the maximum significant wave height. 



(c) Determine the equivalent initial wave height, H^g > for wave 

 growth by 



^e = ^ ^sm • (!'') 



(d) Determine the equivalent fetch length, Fg, for the wave height, 



(e) Determine an adjusted fetch length, F^, for the segment length. 

 Ax, using equations (12) and (13). 



(f) Determine the total fetch, F, from equation (14). 



(g) Determine an equivalent wave height, Hg, for the total fetch 

 and the given windspeed and water depth. 



(h) Calculate the fractional growth by 



H 

 Gi = — . (18) 



sm 



(i) Calculate the decayed wave height at the end of the fetch by 



2. Wave Period . 



As waves decay over the fetch segment, the significant wave period 

 also changes. Very long waves decay rapidly; shorter waves may decay 

 very little (see Figs. 16 and 18). This means that the significant wave 

 period may be reduced. As a conservative estimate, it will be assumed 

 that the wave period remains constant. This is a conservative estimate 

 since longer period waves would produce higher runup on a structure, all 

 other variables being the same. 



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



GIVEN : A coastal area is flooded by a storm surge so that the water 

 depth over the area is 10 feet (3.05 meters). The actual fetch across 

 the area, in the direction of wave travel, is 3,000 feet (914 meters). 

 The area is covered with thick stands of tall grass and a small to 

 moderate amount of brush or low bushy trees in an even distribution. 



38 



