H = 3' Q=? 



T = 8SEC 



^ 



d r = W 



Figure 11. Definition sketch, Example 4 



33. To calculate Battjes' dimensionless freeboard, q , 



5 = ^ = 5 — = 0.96 (18) 



y[tiL~ tan 9 ^/(3)(5.12)(8) 2 Q 



Figure 9 is then entered with c to find values of 8 for k = , 

 < = 0.5 , and k = 1.0 : 



8 = 0.06 , 0.09 , 0.2 as k = , 0.5 , 1 , respectively 



Equation 9 is used to calculate overtopping rate, 



8(0.10 H L tan e) = 8(0. 1 )(3)(5. 12 x 8 2 ) I 



q = 2 6 (19) 



v Battjes ^ 8 



Therefore, 



Q = 0.30 , 0.45 , 1.0 ft-Vsec/ft of dike for < = , 0.5 , 1.0 , respectively 



Discussion 



34. Battjes does not apply his method to rough slopes, i.e., rubble 

 structures. The effective roughness of coastal structures of different mate- 

 rials is discussed in detail in Battjes (1972) and Section 7.2 of the SPM 

 (1984). 



35. Both Battjes' and Roos 1 geometric relation and Hunt's formula were 

 derived for monochromatic waves, not irregular waves. Hunt's formula does not 

 describe the runup of waves which do not break on the structure. Therefore, 

 the more waves in a given spectrum that break, the more appropriate Battjes' 

 method should be. Figure 12 can be used to get a rough estimate of the 



20 



