Runup on impermeable structures having riprap slopes and runup on 

 vertical, stepped, curved and Galveston-type recurved seawalls have been 

 studied on laboratory-scale models by Saville (1955, 56). The results 

 are shown in Figures 7-14 through 7-18. Effects of using graded riprap 

 on the face of an impermeable structure (as opposed to riprap of uniform 

 size for which Figure 7-15 was obtained) are presented in Figure 7-19 for 

 a 1 on 2 graded riprap slope. Wave rundown for the same slope is also 

 presented in Figure 7-19. Runup on permeable rubble slopes as a function 

 of structure slope and H^/gT^ is compared with runup on smooth slopes 

 in Figure 7-20. Corrections for scale effects, using the curves in Figure 

 7-13 should be applied to rimup values obtained from Figures 7-8 through 

 7-12 and 7-14 through 7-18. The values of runup obtained from Figures 

 7-19 and 7-20 are assumed directly applicable to prototype structures 

 without correction for scale effects. 



The use of the figures to estimate wave runup is illustrated by the 

 following example. 



************** EXAMPLE PROBLEM *************** 



GIVEN : An impermeable structure has a smooth slope of 1 on 2.5 and is 

 subjected to a design wave, H = 7 ft. measured at a gage located 

 in a depth d = 15 ft. Design period is T = 8 sec. Design depth 

 at structure toe at high water is dg = 10 ft. (Assume no change in 

 the refraction coefficient between the structure and the wave gage.) 



FIND : 



(a) Tlie height above the SWL to which the structure must be built 

 to prevent overtopping by the design wave. 



(b) The reduction in required structure height if uniform-sized 

 riprap is placed on the slope. 



SOLUTION : 



(a) Since the runup curves are for deepwater height W^ the shallow 

 water wave height H = 7 ft. must be converted to an equivalent 

 deepwater value. Using the depth where the wave height is 

 measured, calculate. 



7-24 



