Table 6 

 Average Shoreline Movement (metres/year) . Charleston 





Harbor 



to Bull 



Island, 



South Carolina 















Survey Date 









1875- 



1921- 



1921- 



1933- 1934- 



1962- 



1964 



Location 



1921 

 1.5 



1933 

 0.5 



1964 



1964 1962 

 1.9 



1983 



1983 



Sullivans Island 



2.6 



[13/7 - 13/13] 



(15) 



(94) 





(94) 





(94) 



Isle of Palms 



2.1 



-0.2 



2.3 



1.8 0.0 



-0.5 



2.1 



[13/14 - 14/8] 



(91) 



(92) 



(8) 



(28) (63) 



(63) 



(36) 



Dewees Island 



-4.2 



6.2 





-4.7 





-4.1 



[14/9] 



(96) 



(96) 





(100) 





(100) 



Capers Island 



-7.3 



-1.1 





-5.3 





-1.5 



[14/10 - 14/11] 



(100) 



(99) 





(99) 





(100) 



Bull Island 



0.7 



-1.9 





-3.0 





-1.5 



[15/1 - 15/6] 



(99) 



(99) 





(98) 





(98) 



Note: Numbers in parentheses indicate percent shoreline surveyed during the 

 given time interval. Numbers in brackets indicate the maps and segments con- 

 tained in the data block; e.g., Bull Island [15/1 - 15/6] extends from map 15 

 segment 1 to map 15 segment 6 . 



88. The summary of transect data for all of coastal reach 3 (Figure 34) 

 is quite different from reaches 1 and 2. Accretion predominates (44.4 per- 

 cent) in this reach over the 1857-1983 time interval. Undoubtedly, the trap- 

 ping of littoral drift north of the Charleston Harbor jetties have played a 

 strong role in this reach. Erosion (30.1 percent) is reduced from reaches 1 

 and 2 (54.9 percent and 40.0 percent, respectively). Only 25.4 percent of 

 reach 3 can be considered stable over the long term. 



Coastal reach 4 



89. The marsh-bordered shoreline of Bull Bay comprises coastal reach 4. 

 The sheltered nature of this bay is reflected in the long-term average shore- 

 line change rates, which reach a maximum of approximately 3 m/year average 

 erosion and 2 m/year average accretion (Figure 35) . Average erosion and 

 accretion in the bay is considerably less than along barrier islands to the 

 south. Maximum rates of accretion occur on the northeast side of the bay, 

 which is most sheltered from dominant northeast quadrant winds and waves. 



75 



