sediment contribution from various processes. A summary of the contribution 

 of landward sediment transfer processes at several Atlantic coast localities 

 is contained in Table Al . Eighty-five percent of the North Carolina coast 

 has been subjected to overwash between 1938 and 1974 (Boc and Langfelder, 

 1977). These data indicate that the magnitude of overwash varies 

 significantly with locality. 



Table Al 



Contribution of Overwash, Wind, and Tidal Delta Deposition 

 to Landward Sediment Transport 



Flood Tidal 

 Overwash Wind Delta 

 Locality %__ _%_ % Data Source 



Outer Banks, 13 14 73 Pierce (1969) 

 North Carolina 



Assateague Island, 12 6 82 Bartberger (1976) 

 Maryland 



Malpeque barrier 48* 52 Armon (1979) 

 system, Canada 



Rhode Island 43* 57 Fisher and Simpson 



(1979) 



* Combined effects of wind and overwash. 



7. A detailed study of overwash texture, composition, and structure 

 was completed by Schwartz (1975). Volume estimates from individual storms 

 were also compiled. During a northeaster (extratropical storm) in February 

 1973, a minimum estimate of 302,000 m-* of washover occurred between Caffeys 

 Inlet and Buxton, North Carolina for an average washover volume of 2.7 m^/m 

 of beachfront for the 113-km stretch of coastline. Assuming that only 20 to 

 25 percent of the barrier experienced overwash, the volume of overwash per 

 unit of overtopped beach was 10.78 to 13.5 m-'/m of beach (Schwartz 1975). 



8. Actual field measurement of overwash processes was accomplished by 

 Fisher, Leatherman, and Perry, (1974) at Assateague Island. Overwash 

 velocities were measured during storm events, and accurate measurements were 

 made of the amounts of beach erosion, dune scarping, and overwash deposition. 

 Instantaneous velocities of overwash surges ranged from 0.5 to 2.4 m/sec with 

 a mean of 1.5 m/sec. Flow depths averaged 0.2 m. 



9. Leatherman, Williams, and Fisher (1977) determined that storm tide 

 height is the most important parameter in determining the magnitude of an 



A4 



