92. Separation of average net shoreline change rates into three periods 

 reveals some changes in erosional character of the bay over the period of 

 study (Figure 37). From 1850 to early 1920's, most of the bay was slightly 

 accretional. The exception to this was the southwest corner, which is ero- 

 sional during all periods, although magnitude of the erosion appears to be 

 decreasing with time. The period from 1920 to early 1960 shows a mix spa- 

 tially of erosion and accretion. The most recent period, from 1960 to 1983, 

 is primarily erosional, with the center of the bay showing a strong erosional 

 signature. Spatial distribution of accretion is at its lowest during the most 

 recent period. Average net shoreline change rates for discrete sections of 

 the bay for each possible survey interval are presented in Table 7. 



93. Unlike the barrier coastline to the south, shoreline changes in 

 Bull Bay are slow and reasonably predictable. Wind, wave, and storm effects 

 are markedly reduced because of sheltering by Bull Island and Sandy Point and 

 shallow bathymetry. With reduction of these parameters as shoreline change 

 agents, the role of relative sea level rise increases. Wave refraction, long- 

 term sea level rise, and short-term storm surge are probably key factors in 

 spatial and temporal erosion/deposition of bay shoreline. Figure 38 demon- 

 strates the stability of this reach. Over 82 percent of Bull Bay coastline 

 has had less than ±1 m/year of shoreline change between 1874 and 1983. The 

 remainder of Bull Bay is eroding (13.9 percent) or accreting (3.9 percent) 

 depending on orientation to waves that can directly enter the bay. 



Coastal reach 5 



94. Coastal reach 5 (Bull Bay to North Inlet), which corresponds to 

 Brown's (1977) cuspate delta geomorphic zone, is characterized by erosion/ 

 accretion trends similar to the barrier island zone (Figure 34) . From Sandy 

 Point north to Cape Romain Harbor entrance, including all of Cape Romain, 

 erosion dominates. Maximum erosion rates of approximately 12 m/year occur in 

 the vicinity of the cape. Murphy Island, just north of Cape Romain harbor, is 

 strongly accretional at its southern end and erosional along most of its 

 northern end. Cedar Island, between branches of Santee River, is entirely 

 erosional. South Island, downdrift of the jetties at Winyah Bay, has gener- 

 ally been accreting over the duration of this data set. Maximum accretion for 

 the entire reach, approximately 9 m/year, is at the southern end of this 

 island. North of Winyah Bay, the area adjacent to the jetties is mildly 

 accretional switching to erosional as North Inlet is approached. Overall, 



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