92. Figure 8 shows the developmental response of the center-line profile in the model. The solid line is 

 the model profile measured after the specified number of waves, and the dashed line is a model profile 

 measured at an earlier point in the experiment. The purpose of Figure 8 is to illustrate the relative change 

 of the center-line profile as it approached equilibrium. A complete set of profiles for test T03 is given in 

 Figure D3 in Appendix D, and the profile measurements are given ir\ Table C3 in Appendix C. 



93. For regular waves, the profile reached a quasi-equilibrium condition somewhere between 1,200 and 

 1,400 waves with very little change occurring thereafter. The most noticeable change occurring after 1,400 

 waves was an observable cross-tank variation in the profile. This variation is shown in Appendix D (Figure 

 D3) by the plots comparing profiles at 1,650 waves. In these plots, the suffix P represents the center-line 

 profile (dashed) while G and C represent profiles along the glass sidewaU and the concrete sidewall, 

 respectively. Figure 9 plots the average of all three profiles after 1,650 waves as compared with the 

 center-line profile (dashed). 



94. This cross-tank variation is thought to have been caused by a small misahgnment of the revetment 

 in the flume which in turn caused nonuniform reflection of waves from the exposed concrete revetment. 

 Similar cross-tank variation was not present in the prototype-scale tests of Dette and Uliczka^. It was 

 noted that the cross-tank variation in the model did not materialize until after the profile was close to an 

 equilibrium condition, even though the revetment was exposed somewhat earlier. This may indicate that 

 the profile is more susceptible to cross-tank perturbations when the profile has reached a qucisi-equilibrium 

 state. If the profile is not close to equilibrium, the onshore/offshore movement of sand seems to overwhelm 

 any cross-tank-induced sediment transport, indicating that storm-induced profile adjustment exhibits a 

 strong onshore/offshore trend^ 



Comparison with Prototype 



95. Representative profile comparisons between prototype and model after equal numbers of waves 

 (Froude scale for morphological development) are given in Figure 10. In these plots the model results have 

 been scaled up to prototype dimensions using the length scale ratio of 7.5. A complete set of profile 

 comparisons is given in Figure E2 in Appendix E (Test T03 versus Prototype). 



96. The comparison after 40 waves (Figure 10) shows that profile development in the model did not 

 match the development in the prototype for the underwater portion of the profile. The form of the 

 prototype profile suggests that massive slumping may have occurred in the prototype, although this has 



'Personal Communication, Dr. Klemens Uliczka, 28 December 1988 



^This trend was also observed in the field during the DUCK85 experiment (Howd and Birkemeier 1987). A prestorm 

 breakpoint bar that exhibited nonuniform alongshore variation became quite linear and moved offshore during the storm. Near 

 the end of the storm, when presumably a near-equilibrium had been reached, alongshore variation in the bar began to reappear. 



37 



