time. The greatest movement occurred for cases with the finer grain size 

 (0.22 mm) and larger values of deepwater wave steepness (Cases 400 and 500). 

 Breakpoint bars that developed on accretionary profiles were almost stationary 

 (Cases 101 and 801). 



56. The speed of bar migration calculated from movement of the bar 

 center of mass is plotted as a function of time in Figure 1 1 for those cases 

 having significant offshore bar movement. In the beginning of a run the 

 response of the profile was rapid, marked by high speeds of bar migration (on 

 the order of 1-3 m/hr); however, bar migration speed decreased considerably 

 after about 10 hr. In Case 911, the bar cyclically moved onshore and offshore 

 with increase and decrease in water level. Case 100 showed onshore movement, 

 probably because the profile eroded back to the end of the tank; exposure of 

 the wall gave rise to reflection of the incident waves and scour, changing the 

 wave conditions and shape of the bar. 



57. For calculation of the speed of bar migration, the main breakpoint 

 bar was considered. If a second bar formed inshore and joined with the main 

 breakpoint bar, only the estimated original seaward most part was used. 



o 



O 



TO 



OQ 



■o 



<V 

 CL 

 CO 



4- 











3- 



400 

 VJ501 









2- 











1- 





-_* 401 / 



V, ^nn 











500 



;_!_ — ' — — h " *-700 



u- 



1 



901 \ 



7\5, /\f^ 





,-^-»~T »x it i R X 1 



60 80 100 







/ 100 



* 911 



Elapsed Time (hr) 



1 -i 











Figure 1 1 . Speed of bar center of mass (^q^) through time 



31 



