FIGURE 4-13 

 NEW ENGLAND 



60- 



40 



20r 



75 2000, 



2025 2050 2075\ 2100 



— < + ^ -* 



New Hampshire Coast 



Cape Cod S, Mass. 



\ \ Narragansett R.I. 



Cape Cod N, Mass. 



Simulated change in wetland area in New England and mid-Atlantic regions. The high sea level 

 rise scenario is shown. Subsidence is modeled as mm/yr. 



Under the high scenario, salt marsh expansion would accelerate and be more advanced by 

 the year 2050 in certain areas than in the low scenario; but the increased flooding in later 

 decades would inundate exposed seaward salt marsh, thus reducing total marsh area, particularly 

 in the more southerly part of the three-state region (Figure 4-14). On Long Island Sound, 

 however, salt marsh might persist without any loss of area even under the high scenario. However, 

 much of the remaining salt marsh should be recognized as recent and perhaps unstabilized salt 

 marsh developed as a consequence of flooding of lowland nonmarsh areas. Much of the original 

 salt marsh would have been lost to shallow water and tidal flats. Thus marsh properties requiring 

 substantial time to develop might not be evident in many of these newly formed marshes. 



In the Maryland-to-Virginia region, a complex pattern of coastal landforms, terraces, and 

 marsh types creates a complex pattern of response. In Delaware, the low scenario reveals the 

 persistence and expansion of marsh as it gains at the expense of undeveloped lowland or fresh 

 marsh until late in the simulation period. But along Chesapeake Bay, where significant 

 subsidence submerges lowland areas and also along parts of the Delmarva Peninsula, tidal flats 

 or sheltered water would replace some salt marsh even by the year 2050. Along the part of 

 Delmarva, Virginia, barrier beaches are breached late in the period, causing the erosion of salt 

 marshes (Figure 4-14). 



The high scenario generally predicts acceleration of the processes observed under the low 

 scenario. Delaware salt marshes expand through the year 2050 but losses may or may not occur 

 afterward depending on location. At Bombay Hook accretion is projected to rise to 10 mm/yr, 

 thus reinforcing the maintenance of salt marsh against the sea level rise. At Cape Henlopen 

 lateral erosion increases, causing salt marsh loss. In parts of Virginia, barrier beaches are 

 inundated and breached earlier and salt marsh loss accelerates as these areas decline. 

 Consequently, accretion rate drops, further accelerating salt marsh flooding. Elsewhere (e.g., in 

 Achilles, Virginia) some salt marsh is preserved, even as late as 2100, partially by the spread of 



110 



