Figure 6, for a slope of 1 on 4 , is somewhat different than Figures 1 to 

 5 for steeper slopes. Plunging waves become the dominant breaker type on the 

 1 on 4 slope, indicating that wave runup can be predicted using a type of for- 

 mula suggested by Hunt (1959) and used by van Oorschot and d'Angremond (1968). 

 Figure 6 shows trend-line curves, using equation (2), for the less steep wave 

 conditions, i.e., 



0.005 < — V ^ 0-0°3 



2 



and a Hunt-type formula is used for the steeper wave conditions, i.e., 

 Hs/gTp 2 > 0.003 where plunging waves dominate. The Hunt-type formulas for Fig- 

 ure 6 are given by the equations 



(3) 



R 2 



— = 1.61 



Hs 



K 



R s 



— = 1.25 



H s 



K 



— = 0.84 



He 



K 



(4) 



(5) 



tan 9 



where the surf parameter, £» is given by 



1 



(Hg/Lo) 1 / 2 cot G 0C (H s /L ) l/2 



L Q is the deepwater wavelength given by 



L„ = 



2tt 



and cot 6 is the cotangent of the angle 6 between the structure slope and the 

 horizontal. 



Figure 7 provides a different perspective and additional insight on the 

 trends to be expected for irregular wave runup. The R s /H s curves from Figures 

 1 to 6 have been transferred to Figure 7 and plotted versus the surf parameter, 

 K, to show the influence of breaker characteristics on runup. When £ < 2.0, 

 most of the larger waves in the incident wave train plunge directly on the 

 structure and R s /H s decreases with increasing H g /gTp 2 and increasing cot 0. 

 This plunging wave region is where a Hunt-type formula (Hunt, 1959) such as 

 equations (3), (4), and (5) is valid. When £ > 3.5, no waves plunge on the 

 structure indicating a standing wave condition or surging wave region. The 

 influence of H s /gTp 2 and cot 6 on R s /H s is reversed for surging waves as 



