Hubbard et al . 1977, Fitzgerald and Hayes 1980) for various subreaches of the 

 South Carolina coast. This data set, which includes the entire coast, empha- 

 sizes the role of inlets in controlling shoreline change history. Average 

 shoreline change is consistently most variable, and maximum shoreline change 

 is greatest in the vicinity of inlets. It is not implied that every inlet- 

 adjacent shoreline is highly variable, but a majority do influence shoreline 

 position for several kilometres up and down drift. 



Future Shoreline Changes 



190. If an old geologic axiom is reworded slightly to "the present is 

 the key to the future," results of this study can be carefully applied to pre- 

 dict future shoreline changes between Tybee Island, Georgia, and Cape Fear, 

 North Carolina. This assumes that factors which have controlled past shore- 

 line erosion/accretion will operate in the same way with the same magnitude in 

 the future. Rates of change given in Appendix A and within various figures 

 and tables throughout this report can be applied to near future estimation of 

 shoreline change. However, accuracy of predictions decreases with increasing 

 projection into the future and/or projection into shoreline areas that have 

 been historically variable. Sea level, sea energy, geology, sediment supply, 

 and human intervention are the variables that control present and future 

 shoreline positions. This report indicates storm waves are important in 

 affecting the shoreline; however, prediction of number and frequency of future 

 storms is impossible. Bathymetry and shoreline orientation have some effect 

 on erosion/accretion also, but through time, these are constantly being modi- 

 fied by waves and currents. Sea level is another important factor determining 

 future shoreline change rates. Over the last 20 million years, sea level has 

 been episodically dropping along South Carolina. Over the last 15,000 years, 

 sea level has risen. Rate of rise has decreased perceptibly over the last 

 4,000 years, although modern tide gages still detect an overall trend of ris- 

 ing sea level. Predictions for the future (Gorman, in preparation) include 

 rapid increases in sea level as the result of climatic warming from human 

 intervention. 



191. Unpredictability of these and other long-term factors coupled with 

 variability of short-term factors such as inlets means prediction of future 

 shoreline change cannot be very accurate with increasing temporal spacing from 



142 



