UNCLASSIFIED 



SECURITY CLASSIFICATION OF THIS PAGEfHTian Data Bnlared) 



Maximum annualized accretion rate during the 27-month study was 18.9 cubic 

 meters per meter of beach front per year at profile line 1 (Fort Story), and 

 maximum erosion rate 11.6 cubic meters per meter per year at profile line 9 

 (Sandbridge) . The ridge-and-runnel morphology typical of many active shore- 

 lines was not observed in the study area. 



Under present conditions, rates of erosion and accretion are independent 

 of the four types of shore usage defined for this study area (commercial , 

 natural, military, and residential). The narrow, erosional beaches are 

 located at the center of the study area in Back Bay National Wildlife Refuge 

 (natural area). Dam Neck (military), and Sandbridge (residential); the wide, 

 accretional beaches are located at the north and south ends of the study 

 area in Fort Story (military) and False Cape State Park (natural). Instead 

 of beach usage, it is suggested that the observed differences result from a 

 nodal zone of diverging longshore transport in the middle of the study area 

 (approximately Dam Neck to Back Bay). North of this zone, net transport is 

 to the north, and south of this zone, it is hypothesized that net transport 

 is to the south. The net, but irregular, movement of sediment out of the 

 middle area explains the narrow, relatively inactive, erosional beaches 

 observed in the middle and the wide, more active, accretional beaches 

 observed on the ends. 



This interpretation supports existing bypassing and sand nourishment 



procedures which place sand at the south end of the Virginia Beach commercial 



reach for natural longshore processes to distribute to the north. The 



measured volume changes of beach sand in this reach, especially when compared 



with adjacent reaches, strongly indicate that the bypassing and nourishment 



procedures are needed for the maintenance of the Virginia Beach commercial 

 beach area. 



Results of reconnaissance inspections of the shores of Currituck County, 

 North Carolina, are included to better relate the Virginia Beach study area 

 to the CERC Field Research Facility at Duck, North Carolina. 



UNCLASSIFIED 



SECURITY CLASSIFICATION OF THIS PA.GE(When DbIb Enl, 



