RELATIVE RUNUP 



R ^ ag 

 H 1 + bS 



H/L 



RIPRAP (AHRENS) 



QUARRYSTONE UNITS IGUNBAKj 



QUADRIPOD UNITS (DAI AND KAMEL)~ 

 .DOLOSSE (BOTTIN, ETALj- 



MODIFIED CUBES (JACKSON) - 



/ / 



TRIBAR UNITS (JACKSON h 



SURF SIMILARITY PARAMETER, J 



Figure 12. Relative runup versus the surf parameter, 

 (after Ahrens and McCartney 1975) 



armor units may have lower crest elevations and, in some cases, less overall 

 volume and cost. This aspect of armor unit characteristics has not been very 

 well explored to date. 



74. A variety of interpolation schemes based on other armor unit param- 

 eters (including stability coefficient, layer porosity, layer coefficient, and 

 combinations of these parameters) failed to yield results similar to the a 

 and b values directly fit to runup data. The marginal correlation of a 

 and b for some armor units to the Ahrens and McCartney (1975) runup equation 

 is an indication that further carefully controlled runup experiments are badly 

 needed. Runup is difficult to measure precisely with instruments on a rough 

 permeable slope; therefore, the above data were measured primarily by manual 

 means. Losada and Gimenez-Curto (1980) also investigated runup on breakwaters 

 as a function of 5 , which is expressed as 



^ = A(1 - e^^) 



(30) 



49 



