PART V: PREDICTION OF FUTURE SHORELINE CHANGES 



95. The NOS shoreline change maps show what happened between Cape Henry 

 and Cape Hatteras from 1850 to 1980. An analysis of the maps quantifies the 

 changes both spatially and temporally. Data regarding historical shoreline 

 changes can provide useful information with which to predict future changes. 

 When the causes of change are imperfectly known, however, it is difficult to 

 predict future changes by extrapolating past trends because the future may 

 not mimic the past. It is not apparent from the results of this study that 

 the magnitude of future changes in shoreline behavior can be forecast. How- 

 ever, future changes at specific sites can probably be estimated for any given 

 time period relative to the average changes which have occurred in the rest of 

 the study area. This section treats these aspects of shoreline change pre- 

 diction separately. 



Temporal Predictions 



96. Great variability was found in change rates within the 1850-1980 

 survey period. It is not unreasonable to assume future changes will be dif- 

 ferent from the 1850-1980 average. The survey record of shoreline changes in 

 the study area is relatively short, intermittant, and nonuniform in frequency; 

 it also lacks noticeable trends through time (Tables 11 and 12, and Figures 45 

 and 46). Consequently, there is limited shoreline change data available with 

 which to extrapolate shoreline changes into the future. In addition, because 

 of the multiplicity of processes involved, it is impossible to evaluate the 

 relative importance of man's impact relative to changes in the natural pro- 

 cesses that caused the shore to accrete or erode. 



Spatial Predictions 



97. Many changes in shoreline position are likely related to local 

 conditions. Because wave, wind, and current data are unavailable over the 

 130-year survey period and throughout the study reach, a direct causal rela- 

 tionship cannot be established to predict those changes. However, most of the 

 alongshore variations in shoreline change appear to be influenced by the prox- 

 imity of the shoreline to inlets, capes, and nearby shore-connected ridges 



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