Table 6 



Virginia, south of Cape Henry 



Table 7: North Carolina, north of Cape Hatteras 



Table 8: North Carolina, west of Cape Hatteras 

 For the same period, Tables 9 and 10 list shoreline change rates for the fol- 

 lowing soundside shoreline reaches: 



Table 9: Cape Henry to Cape Hatteras 



Table 10: Pamlico Sound, west of Cape Hatteras 

 Ocean shoreline change rates 



77. 1850 to 1980. The mean rate of change for the ocean shoreline over 

 the approximately 130-year study period is shown in Figure 28. For those 

 ocean reaches without rates shown, either no shoreline change values were 

 available (i.e., the Corrolla to Duck, North Carolina, reach), or a major 

 change in shore orientation (i.e., Capes Henry and Hatteras) or a break in the 

 barrier island system (i.e., Oregon Inlet) precluded the determination of a 

 usable ocean shoreline change rate. Between about 1850 and 1980 where data 

 were available, approximately 28 percent of the ocean shore prograded, 68 per- 

 cent retreated, and 4 percent did not change position. 



78. Average shoreline change rates should be used with caution for 

 planning and design purposes because large temporal and spatial variations in 

 the rates have occurred in the past and can be anticipated to occur in the 

 future. The standard deviation of shoreline position changes with time is a 

 measure of these temporal variations. Large standard deviation values indi- 

 cate a large variability in shoreline change rates between different surveys; 

 smaller values indicate the shoreline change rate has been more nearly con- 

 stant from one survey interval to the next. Figure 29 shows the standard 

 deviation and the number of surveys used to calculate it for the east-facing 

 ocean shore. Shoreline changes north of Oregon Inlet were relatively constant 

 from 1852 to 1980 when compared to the changes south of Oregon Inlet to Cape 

 Hatteras. Greater variations in shoreline position are the norm for the 

 latter 60-km-long reach. 



79. Partial study period. Dates of survey allow a separation of the 

 data set into two nearly equal time intervals. It is useful to compare ocean 

 shoreline changes for those two periods for several reasons. During the 

 period from about 1850 to 1915-1925, the shoreline underwent mostly natural 

 changes, except for the dune vegetation loss caused by grazing animals. Dur- 

 ing the period from 1915-1925 to 1980, human intervention in the form of 



62 



