Table 47. Area of barrier environments, Old North Beach. 



[Xjne9 Uashovera Marshes Shrub.; Sandy Total 



shorelines supratldal 

 environments 

 (h a) (pet) 1 (ha) (pet) (ha) (pet) (ha) (pet) (ha) (pet) (ha) (pet) 



62.2 450.2 

 95.9 +54 470.4 +4 



36.3 -62 422.4 -10 



57.0 +57 461.8 +9 



46.6 -18 421.5 +9 

 -25 -6 



1868 



194.3- 





194. 3 2 





193.7 





2 





1886 



191. 7 i 



-1 



191. 7 2 



-1 



182.8 



-6 



2 





1938 



162.6 





67.4 





148.3 



-19 



7.8 





1952 



133.2 



-18 



137.3 



+ 104 



123.9 



-16 



10.4 



+33 



1978 



187.3 



+41 



28.5 



-79 



138.4 



+ 12 



20.7 



+99 



change 



'Lncreaae and decrease In hectares. 

 a The 1868 and 1886 maps do not dlffe 



Table 48. Location of changes in total barrier 

 area calculated from serial map 

 overlays, Old North Beach. 



Year 





Savs 

 Loss 



(ha) 



hore 

 Gain 



(ha) 



Ccear. 



front 



Sptt t 

 Loss 

 (ha) 



erminus 

 Cain 

 (ha) 



Total 





Loss 

 (ha) 



(ha) 



Loss 



(ha) 



1868 to 



1886 



21.8 



31.9 



26.7 



3.1 



0.0 



3J.7 





1886 to 



1933 



7.8 



44.0 



84.2 



0.0 



0.0 



0.0 





1938 to 



1952 



10.4 



71.0 



27.9 



6.7 



0.0 









1952 to 



1978 



22.9 



29.9 



50.9 



3.6 



0.0 



0.0 





1868 to 



l i ;78 



62.9 



176.8 



184.5 



13.4 



0.0 



33.7 





Net 







113.9 



171.1 







13.7 



28.7 



bay side. In other areas supratldal environment was added to the back barrier 

 by rhizome extension coupled with gradual tidal sedimentation and by overwash., 

 A total of 176.8 hectares was added to the back, barrier (Taole 43). During 

 the past 110 years, 247.4 hectares (55 percent of the 1868 total area) has 

 eroded from Old North beach, but 223.9 hectares (53 percent of the 1978 area) 

 has been added to the barrier, primarily along the bay shoreline. 



Between 1886 and 1938 the Old North Beach shoreline eroded at a rate of 

 1.7 meters per year, and 63.8 hectares of dune-washover was lost along the 

 oceanside (Tabie 49). New dunes developed on areas that had been buried by 

 overwash deposits (50 percent). 



By 1952 overwash had eliminated large sections of the dune line (23.4 

 hectares) and shoreline erosion continued to level dunes (37.2 hectares) at a 

 rate of 2.7 meters per year. Dunes developed between 1938 ai.d 1952 on wash- 

 overs (25*2 hectares) and on salt marshes buried by overwash (11.7 hectares). 

 The large washovers present in 1952 (137.3 hectares — 30 percent of the total 

 area of Old North Beach) had been partly colonized by dune vegetation by 1978; 

 70.5 hectares of dunes developed on these washovers. Although shoreline ero- 

 sion continued at a rate of 1.3 meters per year, only 18.8 hectares of dunes 

 was eliminated along the ocean shoreline because the dune field had been 

 poorly developed in 1952. 



176 



/ 



