MAX. CHANGE VS WAVES WITH T> 1 1 



PER WIS SEGMENT 



200 400 600 



MAX. SHORELINE MOVEMENT (M) 



Figure 58. Maximum net shoreline movement versus occur- 

 rence of waves with a period greater than 11 sec 



(Figures 26 and 42). May (1983) noted that 55 to 60 percent of the energy 

 supplied to the coast of North Carolina was from swell waves. The data point 

 in each group that shows largest shoreline movement is the WIS segment immedi- 

 ately south of a Cape. Where T > 11 sec occurrence is low, the WIS segment 

 south of Cape Fear has largest shoreline changes. Of the northeast -southwest 

 trending shoreline group, the WIS segment just south of Cape Romain has 

 largest shoreline changes. In the group of high percent occurrence of T > 

 11 sec , Tybee Island (which is capelike in morphology) has most shoreline 

 movement. These data do not demonstrate any relationship between wave period 

 and maximum shoreline movements, but they do hint that shoreline orientation 

 plays an interactive role with waves in affecting erosion/accretion of the 

 shoreline. 

 Shoreline orientation 



175. Shoreline orientation with respect to predominant average and 

 storm wave approach affects wave and current conditions in the littoral zone 

 and, thus, may contribute to shoreline changes. To examine this factor, 

 orientation of each coastal segment (Figures 22a and b) in the study area was 

 determined, and scatter plots of orientation versus average annual and maximum 

 shoreline change were prepared. 



128 



