24 





















20 



- 



. Standard Deviation 





16 





' 





12 



" 







8 



_ 





















— 



" 















_ 



"1 ° 



E 



1 " 



- 









1" 













_ 









I J 











= -8 

















Mean 









-12 



- 

















■ie 

















-20 











-24 



.5fl 



" . 



1 1 



Sandard Deviation 



1 



1 1 



Figure 27. Mean and standard deviation of unit volume changes 

 by profile for 17 selected. storms at Atlantic City. 



addition to having the smallest deviation of all profiles. Profile line 4, 

 therefore, appears to maintain a reasonably stable unit volume throughout 

 storms. This apparent anomaly may possibly be related to the number and type 

 of structures near the profile; i.e., Steel Pier and Steeplechase Pier updrift 

 of the profile, as well as two groins located on either side of Steel Pier 

 (Table 1). In addition, another groin located just downdrift of the profile 

 causes a "boxed-in" effect which could possibly contain a bulk of the littoral 

 material. 



Figure 28 illustrates the mean unit volume changes and standard deviations 

 by contour above MSL for all profile lines during the selected storms. The 

 greatest average unit volume loss occurs between the +0.5- and +1. 0-meter con- 

 tours. The figure also shows that the greatest deviations from the mean occur 

 between the 0.0- and +2. 0-meter contours. This is to be expected because wave 

 action is concentrated in the foreshore region and thereby lends to greater 

 variations in volumes of material moved. Also, it is possible that the maxi- 

 mum average unit volume loss occurs between the +0.5- and +1. 0-meter contours 

 because the average maximum surge above high water, which allows waves to con- 

 centrate, during those storms is 0.57 meter. Alternately, the variation in 

 volume change generally decreases with increasing elevation above +2.0 meters 

 because this part of the profile remains relatively stable, except in severe 

 storms, due to its increased distance from the scouring effects of wave 

 action. This higher part of the beach not only remains relatively stable, but 

 it accretes an average of 0.21 cubic meter per meter per storm between the 

 3.0- and 3.5-meter contours. 



Since losses from the lower contours clearly exceed gains along the upper 

 contours, sand is moving either offshore or alongshore. The most intense 

 storms resulted in -20 cubic meters per meter volume changes above MSL, which 



34 



