155. Holman and Sallenger (1985) analyzed an extensive field data set 

 of runup on a barred beach. Although there was wide scatter in the data, they 

 concluded that runup appeared to depend on £ . However, the choice of slope 

 with which to calculate £ was unclear. The foreslope appeared to be appro- 

 priate for data taken at high tide and midtide, whereas the bar slope appeared 

 to "have at least some influence" on setup at low tide. (Runup is defined as 

 the combination of a superelevated MWL, called setup , and a time dependent 

 quantity called swash.) It is not clear if the bar was a major cause of wave 

 breaking in their low- tide measurements. The present tests with regular waves 

 indicate that the bar has a very weak influence, if any, on runup if waves 

 break on the bar. In agreement with Holman and Sallenger, the foreshore, or 

 wide-area slope, appears to be the best quantity to use in correlating R/H 

 with £ ; however, only one slope (1/30) was used in the present study, so 

 this conclusion can only be tentative. 



Wave Steepness Scaling 



156. A subtest was performed to determine if the magnitude of wave 

 height and period had an effect on wave breaking properties. Cases 6210, 

 6220, and 6230 each had a nominal wave steepness H /L = 0.05 , but this 

 ratio was obtained with different wave periods and heights, listed in 

 Table 12. Breaker depth and height indices, runup, and reflection coeffi- 

 cients were determined from these tests and are also listed in Table 12. 

 Figures 62 (a-c) -64(a-c) show the wave forms at incipient breaking for the base 

 test (a) and the two variations (b,c). The wave forms for the base test and 

 scaled variations show the incipient breaking wave is similar, but not iden- 

 tical, and has the same breaker type for corresponding seaward bar angles. 

 Breaker depth values for the variation cases follow the trend of the base 

 case; however, breaker height indices and reflection coefficients show great 

 variation and no apparent trend. Although runup values show deviations 

 between the variation cases and base cases, the values are nearly constant. 

 Because runup was shown to depend on wave steepness and primary slope (m) , not 

 bar slope, this result is not unexpected. 



157. The subtest was inconclusive and not successful in proving or dis- 

 proving if wave period and wave height individually exert influence on wave 



115 



