and empirical coefficients, as in Figure 2, is interpolating between 



dimensional parameters.* For a given structure and water depth, each Q* - a 



point in Figure 2 will yield a dimensional overtopping rate for a specific 



combination of H and T . This is because, for each Q* - a point, the 



given water depth and d /H' determine H' , which determines T through 

 ° _ s o o 



H'/gT . These results can be plotted on an H - T plane, and overtopping 

 rate contours can be interpolated. This procedure is outlined below and used 

 in Example 2. Figure 4 is the dimensional overtopping plot from the example. 



17. Seelig recommends the following design procedure for estimating 

 wave overtopping for engineering design. This procedure can be used when 

 interpolation for Q* and a. is necessary: 



a. Gather design data, H s , T , d s . 



b. Choose the most appropriate Q* - a figure from the SPM 

 (Figures 7-24 through 7-32). ° 



c. Convert the dimensionless data into dimensional overtopping 

 rates. For the known d s , each data point yields an 

 overtopping rate Q for one H s and T combination. 



d. Plot Q's on an H versus T plane. 



e. Interpolate from the dimensional plot for the design H„ and 



Example 2 



18. Using the SPM method and the procedure outlined above, an estima- 

 tion can be made of the volume rate of overtopping of a 1:3 smooth-slope 

 structure in 10 ft of water with 5 ft of freeboard created by waves with a 

 significant wave height H s of 4 ft and a design wave period T of 8 sec. 

 Step 1 H s = 4 ft 

 T = 8 sec 

 d s = 10 ft 

 F = 5 ft 

 Step 2 Figure 2 (SPM Figure 7-26) is the correct figure. 



Step 3 Calculate an H s , T , and Q for each Q* - a point on 

 Figure 2. 



Step 4 See Figure 5. 



Step 5 Interpolating in Figure 5 for the design variables H s 

 = 4 ft and T = 8 sec yields Qo PM =0.5 ft^/sec/ft of 



seawall . 



* Personal Communication, Seelig 1983. 



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