Plunging Region 

 (Waves Plunge Directly 



on Structure) Cotfi=2.0 



Transition 

 Region 



Surging Region 

 (Standing Waves Against Structure) 



I \ 



Cotfi = 2.5 



Cot0=3.O 



Cot 8 = 4.0 



Cotfl=3.0 



Cotfl=2.5 



Cot fi=2.0 



Surf Pnrameter, £ 



Figure 7. R s /H s versus the surf parameter for d s /H s > 3. 



compared to plunging waves; i.e., R s /H s increases as H s /gTp 2 increases and cot 

 increases. The reversal of influence creates a transition region, 2.0 < 

 £ < 3.5, where there is little net influence of H s /gT p 2 and cot 6 on R s /H g . 

 It is in this transition region that the largest values of R s /H s occur, prob- 

 ably because the most nonlinear surging waves occur in this region. Figure 7 

 identifies these regions and shows the runup trends. Equations (3), (4), and 

 (5) can be used on slopes flatter than 1 on 4 as long as plunging waves pre- 

 dominate, i.e., E, < 2.0. 



All the results in this report were obtained in relatively small-scale 

 laboratory studies and must be corrected for scale effects (Stoa, 1978a). 

 The correction for scale effects of wave runup on smooth slopes can be found 

 in Stoa (1978b) (shown in App. A). Example problem 1 in Section V illustrates 

 the method of applying this correction. 



The results in Figures 1 to 7 are all presented in terms of the significant 

 wave height at the toe of the structure, H s , rather than the deepwater, un- 

 refracted wave height, Hq. If it is desired to convert the results of this 

 study to deepwater conditions, H s should be multiplied by the shoaling coef- 

 ficient, given in Appendix C of the SPM (U.S. Army, Corps of Engineers, Coastal 

 Engineering Research Center, 1977), calculated using d s and T p to obtain an 

 estimate of the deepwater, unrefracted significant wave height. 



III. IRREGULAR WAVE RUNDOWN 



Irregular wave rundown is characterized by the 98 percentile rundown, Rdg8, 

 i.e., the rundown depth below the Stillwater level which is greater than 98 

 percent of the wave rundowns. The irregular wave rundown parameter, Rdge is 

 analogous to the runup parameter, R2 , since only 2 percent of the rundowns 

 are lower than Rd 98 . Figure 8 shows the trend of the relative rundown, 

 Rdgg/Hg as a function of the surf parameter, £ , and the approximate upper 



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