The long-term change for most beaches in the study is negative, 

 which signifies a long-term erosional trend. This is due primarily to 

 the inability of the beach to return to its original position after a 

 particularly severe winter storm period or after a very severe isolated 

 storm (e.g., a hurricane or tropical storm). During storm activity, 

 sediment is eroded off the upper section of the beach profile and 

 transported either alongshore in the littoral drift or offshore. 

 Particularly severe storms can result in sediment being transported 

 sufficiently far offshore to preclude its return to the beach face under 

 more favorable conditions, thus resulting in a sediment deficit and, 

 hence, erosion. Also important during the erosional phase of beach 

 behavior is the continual exposure of "fresh" beach sediment which may 

 not have the appropriate sediment distribution/ characteristics for the 

 dominant wave conditions. This means that under erosional conditions, 

 sorting losses can continually occur (resulting in long-term losses), 

 the magnitude of which is dependent upon the degree of mismatch between 

 the distribution of the exposed sediment to that which is more suitable 

 for the wave conditions. Another cause for the long-term erosional 

 problem is a rise in sea level position. Based on an equilibrium bottom 

 profile, Bruun (1962) quantified the volumetric erosion loss per unit 

 length of shoreline (V) as 



V = (e + d) (X) 



(1) 



where X is the rate of shoreline recession, e is the berm crest MSL, and 

 d is the limiting depth between nearshore and offshore processes. 



Limiting depth (d) is approximately -8.2 meters (MSL) based on 

 inspection of long profiles from Wrightsville and Carolina Beach data. 

 Horizontal distances to this depth for the control cells are presented 

 in Table 6. The rate of shoreline recession is expressed by 



X = 



ab 



(e + d) 



(2) 



where a is the rate of local sea level rise, and b is the distance from 

 the initial shoreline to the limiting depth. 



Table 6, 



Volumetric and excursion losses due to rise in MSL. 





Distance (b) 



Volumetric 



Excursion rate 





to limiting 



loss/ unit 



due to sea 





depth of 



lgth of beach 



level rise 



Littoral Cell 



-8.2 m 



(m-Vyr/m) 



(m/yr) 



Wrightsville Beach 



225 



0.83 



-0.10 



Masonboro Beach 



210 



0.78 



-0.10 



Carolina Beach 



190 



0.70 



-0.09 



Kure Beach 



180 



0.67 



-0.08 



Fort Fisher Beach 



220 



0.81 



-0.10 



