preliminary. A more rigorous approach, which will define shoreline segments 

 based on records of erosion and/or accretion, is planned for future reports by 

 the authors. Comparison of wave and erosion/accretion data for each segment 

 was additionally complicated since WIS data are summarized only in 16-km-long 

 blocks. Therefore, erosion/accretion data had to be further grouped to match 

 16-km WIS spacing. 



Waves 



169. Using power spectrum analysis and principal component analysis, 

 May (1983) compared WIS data for the North Carolina coast to eight shore zone 

 attributes, including shoreline change. For most of North Carolina, there was 

 no correlation between wave climate and shore zone rate of change. In a few 

 areas, however, low-period, high- amplitude waves correlated with high erosion. 

 Wave height 



170. Average net shoreline change was calculated for every 16-km seg- 

 ment of coastline defined by WIS. Average shoreline change was compared with 

 average wave height, maximum significant wave height, and occurrence of sig- 

 nificant wave height greater than 1 and 2 m. Each of these wave height param- 

 eters was further compared with maximum shoreline change (the envelope of 

 change between the two most divergent shorelines irrespective of their dates) 

 for each 16-km section of shoreline. 



171. Average wave height, which ranged between 0.48 and . 74 m along 

 the coast, showed no apparent trends when compared with average shoreline 

 change. Likewise, average shoreline change versus maximum significant wave 

 height (2.6 - 5 . 3 m) and occurrence of significant wave heights greater than 

 1 m, showed no apparent relationship. Average shoreline change versus occur- 

 rence of significant wave heights (Hs) greater than 2 m does show some trends 

 (Figure 54) . Data suggest less erosion and more accretion as occurrence of 

 waves greater than 2 m decreases. Generally, in those areas where large waves 

 (Hs > 2 m) hit the shoreline relatively often, average rates of erosion are 

 expected to be larger. 



172. Maximum shoreline change versus significant wave heights in excess 

 of 1 and 2 m showed no apparent organization. Maximum shoreline change versus 

 average significant wave height (Figure 55) showed a very weak suggestion of 

 increasing shoreline movement with increasing average height; however, there 



124 



