conditions extend the region of suspended sediment movement farther offshore due to variations in the 

 location at which the waves break. 



231. Experiment repeatability was shown to be well within acceptable limits, and overall, the attempts 

 to validate the modeling guidance for the ca^e of turbulence-induced scour of noncohesive sediment was 

 judged by the authors to be successful. However, it was noted at present that this verification is 

 encouraging only to the extent that prototype-scale wave tank tests can reproduce natural beach response 

 without adverse laboratory effects. 



232. Model tests in which wave parameters were slightly changed were conducted to assess the 

 importance of the fall speed parameter on the profile response. Increasing the height of regular waves by 

 10 percent promoted additional offshore transport of sediment, as did decreasing the wave period by 



10 percent. Similar profile development was seen when these slight variations in wave parameters resulted 

 in the same value for the fall speed parameter, but this distortion of Froude-scaled hydrodynamics was not 

 recommended for other than slight perturbations in the wave parameters. 



233. Initial profile differences in the model experiments did not substantially affect the ultimate 

 outcome of the experiments as the profile approached near-equilibrium; however, short-term differences 

 were observed. It is possible that great differences in initial profile slopes could have an impact on final 

 profile configuration, but no tests were conducted with radically different initial slopes. 



234. Movable-bed tests in which the sloping revetment became exposed were conducted using irregular 

 waves to determine which irregular wave parameter is best suited for use in comparing results from 

 regular-wave tests. Best results at equilibrium were obtained when the significant wave height of the 

 irregular waves Wcis equivalent to the regular wave height, even though the irregular waves contained about 

 30 percent less total energy. Equivalent profile development took about twice as long under irregular 

 waves, and a simple explanation is that the irregular wave train included accretive as well as erosive waves 

 and it appeared that the larger waves were most responsible for profile development. 



235. Placement of a vertical seawall on the sloping revetment effectively denied the profile of the sand 

 shoreward of the seawall. Both regular and irregular wave tests were conducted to examine the 2-D 

 impacts of this situation. The additional erosion observed in front of the seawall was approximately equal 

 to the amount of sediment being held behind the seawall that otherwise would have eroded if the seawall 

 were absent. For the irregular wave case, the additional eroded volume in front of the seawall was about 

 83 percent of the amount being withheld by the seawall. These findings are generally in agreement with 

 results obtained by others. Comparisons between the irregular and regular wave tests with the seawall 

 intact confirmed that making i/1/3 of the irregular waves equal to Hmono gives best correspondence 

 between profile erosion tests. 



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