broken into 999 runups, instead of 199, to properly account for the effect of 

 the higher runups. Equation 3 becomes 



999 



"SPM " 999 



99 i?i Qi 



(5) 



where 



p = 0.001 x i, i = 1, 2,..., 999 

 Example 1 



14. Using the SPM method, an estimation can be made of the overtopping 

 rate for a proposed 15-ft-high structure* (1:3 smooth slope) in 10 ft of water 

 caused by waves with a significant wave height H g of 5 ft and a design wave 

 period T of 8 sec (Figure 4). To find R g , runup of a 



T=8s 



-E 



Q=? 



d= 10 



r77777Z77s 



Figure 4. Definition sketch, Example 1 



monochromatic wave of H' = 5 ft and T = 8 sec: 



o 



gT 2 (32.2M8) 2 



= 0.0024 TjT = ^ 



(6) 



From SPM Figure 7-11, R/H 1 = 2.75. From SPM Figure 7-13, scale effects 

 correction factor, k = 1.14. Therefore, 



R = Jr (H^)(k) = (2.75X5 ft)(1.l4) = 15.7 ft = R £ 

 o 



(7) 



To find Q* and a , Figure 2 (SPM Figure 7-26), with d g /H^ = 2 , 



and 



H'/gT = 0.0024 , yields 



* A table of factors for converting non-SI units of measurement to SI 

 (metric) units is presented on page 3. 



10 



