shown in this figure includes data mainly from preconstruction of the jetties. 

 The result is an average erosion rate exceeding 5 m/year. The second period, 

 from early 1920 's to early 1960's, shows a postconstruction phase of erosion 

 that has shoreline erosion rates exceeding 20 m/year. Morris Island is 

 clearly sediment starved as a result of the jetties. The early 1960 's to 1983 

 graph shows continued erosion of Morris Island; however, despite the shorter 

 time interval represented, magnitude of the erosion has decreased. Erosion 

 rates over this 20-year interval barely exceed 10 m/year. Folly Island is 

 generally eroding during all three time intervals. Accretion along the length 

 of Folly Island appears to be at a minimum during the 1960 to 1983 period. 

 Along Kiawah Island, erosion and accretion seem to reverse with changing time 

 intervals. The most recent period shows Kiawah to be largely accretional. 

 Edisto Island has been erosional through time, except at the very southern 

 end. Pine and Otter Islands were accretional during the 1850 to 1929 time 

 period, but have been largely erosional since then. A summary of average 

 shoreline change rates per island for every available time interval is pre- 

 sented in Table 5 . 



84. The summary of data within reach 2 (Figure 30) shows erosion to be 

 dominant (40.0 percent). However, despite the effects of Charleston Harbor 

 jetties, the percent occurrence of accretion is greater (28.5 percent) than in 

 reach 1 (14.6 percent). Approximately 31.5 percent of the transects measured 

 in reach 2 showed +1 m/year or less change between 1851 and 1983. 



Coastal reach 3 



85. Coastal Reach 3 (Charleston Harbor to Bull Bay) also falls within 

 Brown's (1977) barrier island geomorphic zone and is similar in character to 

 reaches 1 and 2 discussed previously (Figure 31). Average net accretion 

 varies up to a maximum of approximately 6 m/year, and average net erosion 

 exceeds 8 m/year. Sullivans Island and Isle of Palms, both immediately north 

 of the Charleston Harbor jetties, predominantly show accretion. Rate of 

 accretion increases toward the jetties, suggesting trapping of littoral drift 

 as the reason for sediment accumulation. Dewees and Capers Islands, north of 

 Isle of Palms, are predominantly erosional, although both show a small area of 

 accretion near their northern ends. Bull Island, the northernmost barrier 

 island in this reach and within Brown's barrier island geomorphic zone, starts 

 out strongly accretional in the south and ends up strongly erosional at its 

 northern terminus . 



68 



