Table 3. Local wave conditions for various offshore slopes 

 and water depths based on Goda's (1975) model. 



-. 



U;/ l 



- 0.002 



H o /L o 



- 0.005 



"o /L o " °' 010 



"o/H, 



- 0.020 



H o /L o 



- 0.040 



«o'^ 



- 0.080 



H o 



Vo 



"max^U 



V«o 



>W H s 



H s /H o | "max^-s 



V'Ho 



■W H s 



H s /H o 



>W H s 



H s /H o 



"max/"* 







OffBhore slope - 1 on 



10 











0.5 



0.83 



1.49 



0.76 



1.38 



0.70 



1.32 



0.63 



1.30 



0.58 



1.31 



0.51 



1.24 



1.0 



1.26 



1.35 



1.18 



1.29 



1.11 



1.26 



1.02 



1.26 



0.94 



1.25 



0.80 



1.26 



1.5 



1.67 



1.30 



1.59 



1.27 



1.45 



1.30 



1.26 



1.38 



1.06 



1.44 



0.89 



1.42 



2.0 



2.04 



1.28 



1.85 



1.35 



1.49 



1.52 



1.16 



1.61 



0.99 



1.62 



0.91 



1.54 



2.5 



2.00 



1.32 



1.74 



1.46 



1.31 



1.60 



1.06 



1.61 



0.95 



1.61 



0.91 



1.58 



3.0 



1.87 



1.39 



1.56 



1.54 



1.18 



1.62 



1.03 



1.59 



0.96 



1.58 



0.95 



1.59 



3.5 



1.73 



1.46 



1.41 



1.59 



1.11 



1.61 



0.99 



1.61 



0.95 



1.58 



0.95 



1.61 



4.0 



1.60 



1.53 



1.30 



1.61 



1.06 



1.61 



0.97 



1.62 



0.94 



1.58 



0.97 



1.61 













Offshore slope - 1 on 



20 











0.5 



0.60 



1.50 



0.56 



1.39 



0.51 



1.34 



0.48 



1.29 



0.44 



1.26 



0.40 



1.23 



1.0 



0.95 



1.36 



0.91 



1.28 



0.86 



1.26 



0.82 



1.24 



0.75 



1.24 



0.67 



1.24 



1.5 



1.31 . 



1.29 



1.25 



1.26 



1.18 



1.26 



1.08 



1.30 



0.95 



1.34 



0.81 



1.33 



2.0 



1.64 



1.28 



1.55 



1.28 



1.36 



1.38 



1.13 



1.50 



0.98 



1.53 



0.88 



1.44 



2.5 



1.90 



1.31 



1.67 



1.41 



1.29 



1.58 



1.06 



1.61 



0.94 



1.61 



0.91 



1.51 



3.0 



1.87 



1.39 



1.56 



1.54 



1.18 



1.62 



1.03 



1.59 



0.94 



1.61 



0.94 



1.56 



3.5 



1.73 



1.46 



1.41 



1.59 



1.11 



1.61 



0.99 



1.61 



0.94 



1.60 



0.96 



1.57 



4.0 



1.60 



1.51 



1.30 



1.61 



1.06 



1.61 



0.97 



1.62 



0.94 



1.58 



0.96 



1.60 













Offshore slope ■ 1 on 



50 











0.5 



0.50 



1.51 



0.46 



1.41 



0.43 



1.35 



0.40 



1.29 



0.38 



1.25 



0.35 



1.24 



1.0 



0.80 



1.35 



0.77 



1.28 



0.74 



1.25 



0.70 



1.24 



0.65 



1.24 



0.59 



1.22 



1.5 



1.12 



1.28 



1.08 



1.25 



1.03 



1.25 



0.96 



1.26 



0.87 



1.28 



0.75 



1.29 



2.0 



1.44 



1.25 



1.37 



1.26 



1.25 



1.31 



1.08 



1.41 



0.94 



1.45 



0.84 



1.38 



2.5 



1.68 



1.29 



1.54 



1.34 



1.27 



1.49 



1.04 



1.58 



0.94 



1.57 



0.89 



1.46 



3.0 



1.83 



1.36 



1.53 



1.51 



1.18 



1.61 



1.02 



1.61 



0.94 



1.60 



0.92 



1.51 



3.5 



1.73 



1.46 



1.41 



1.59 



1.11 



1.61 



1.00 



1.59 



0.93 



1.61 



0.94 



1.55 



4.0 



1.60 



1.53 



1.30 



1.61 



1.06 



1.61 



0.97 



1.62 



0.93 



1.61 



0.97 



1.57 













Offshore slope - 1 on 



100 











0.5 



0.48 



1.50 



0.44 



1.40 



0.41 



1.35 



0.38 



1.29 



0.36 



1.25 



0.33 



1.24 



1.0 



0.77 



1.34 



0.74 



1.28 



0.71 



1.25 



0.68 



1.24 



0.63 



1.23 



0.58 



1.21 



1.5 



1.07 



1.28 



1.03 



1.25 



1.00 



1.24 



0.92 



1.26 



0.84 



1.28 



0.73 



1.28 



2.0 



1.36 



1.26 



1.31 



1.26 



1.21 



1.30 



1.06 



1.38 



0.93 



1.42 



0.83 



1.37 



2.5 



1.62 



1.28 



1.50 



1.32 



1.25 



1.47 



1.04 



1.56 



0.94 



1.55 



0.88 



1.44 



3.0 



1.78 



1.35 



1.52 



1.47 



1.18 



1.60 



1.02 



1.61 



0.94 



1.61 



0.92 



1.50 



3.5 



1.73 



1.46 



1.41 



1.59 



1.11 



1.61 



0.99 



1.60 



0.93 



1.61 



0.94 



1.53 



4.0 



1.60 



1.53 



1.30 



1.61 



1.06 



1.61 



0.97 



1.62 



0.94 



1.60 



0.97 



1.55 



*************** EXAMPLE PROBLEM 4*************** 



GIVEN : A riprap revetment with a slope of 1 on 2.5 is to be built where the 

 design water depth at the toe is 4.57 meters (14.99 feet). Seaward of the 

 toe, the offshore slope is 1 on 100. The deepwater, unrefracted, signifi- 

 cant wave height is 3.05 meters (10.01 feet) and the design wave period is 

 7.0 seconds. Assume no wave refraction from deep water to the structure site, 



FIND : The elevation above the design water level to which the riprap must 

 extend to prevent being exceeded by the runup . 



SOLUTION : The first method follows the procedure of Stoa. For d s /Ho =1.5, 

 Table 4 and Figure 5 (App. A in Stoa, 1979) indicate that the smooth-slope 

 reduction factor, r, for runup on riprap on a 1 on 2.5 slope is r = 0.63, 

 To find the smooth-slope runup, Figure 6 (Fig. 10 in Stoa, 1978) is used 

 with 



Hi 3.05 

 gT 2 ~ ~ 9. 80(7. 0) 2 



= 0.0063 



which yields R/Hq = 2.05. According to Stoa (1979), there is no scale cor- 

 rection for this condition, so the runup is 



20 



