9 
species--Distichlis spicata, Salicornia sp, Batis maritima, Sporobolus virginicus, 
Limonium nashii, Iva frutescens, Borrichia frutescens, Spartina patens, and Juncus 
roemarianus--are found where the elevation is higher or the tidal inundation less 
frequent. Where large tidsl rivers such as the Altamaha (Georgia) discharge large 
quantities of fresh water, the vegetation changes from typical Spartina alterniflora 
marsh to a Juncus roemarianus marsh with Spartina alterniflora on channel banks 
and tidal creek heads. Moving inland, as the water becomes fresher, Spartina 
alterniflora is replaced by Spartina cynosuroides, and patches of Scirpus sp. 
(three square, bulrush) are found with Juncus roemarianus. Gradually species 
diversity increases, and fresh water species such as Typha sp. (cattail), 
Peltandra virginica (arrow arum), Zizania aquatica (wild rice), Zizaniopsis 
miliancea (giant cutgrass) compose an appreciable portion of the marsh vegetation. 
Wooded swamp may take the place of these fresh marshes. 
  
  
  
  
  
  
  
  
The uppér wetland boundary is often sharply defined by an abrupt change in 
topography. The marsh may extend as much as 30 feet under the canopy of large 
trees in the border zone. Where a broad and gradual transition occurs with a 
mixture of plant species present, the upper wetland boundary is more difficult 
to define. On the other hand, the transition zone may be extremely narrow, 
covered with Borrichia frutescens, Iva frutescens, Juncus roemarianus, and 
Scirpus americanus. Small patches of Borrichia frutescens are commonly found 
along the levees characteristic of the water edges of Georgia marshes. Open 
mudflats, ranging from organic to sandy, may be quite extensive; they are easily 
misidentified on photographs and mapped as high ground. 
  
  
With a knowledge of the plant species, the morphology of the land, the tidal 
cycle, and the applicable laws, one can usually position the upper wetland boundary 
within 10 or 15 feet horizontally during field inspection. The task is easier and 
equally accurate when the boundary is delineated from color-infrared aerial photo- 
graphs offering a much larger view. For 5 to 10 percent of the area, the task is 
more difficult using either method. The transition in these areas may be very 
gradual and indistinct, requiring more judgment, careful surveys, and intelligent 
legislation. Litigation may be necessary, for there is no one technique for pro- 
viding unequivocal answers to wetland boundary questions. 
MAPPING THE COASTAL WETLANDS 
A review of present and proposed coastal wetland regulations of several 
States reveals that-- 
e There is a requirement to provide an accurate cartographic base on which 
upper wetland boundaries and other coastal-zone features can be accurately 
plotted. 
e It is desirable to provide the map user with an orthophotoimage for more 
information about features that are not specifically delineated or are 
necessarily generalized on the conventional map. 
Selected areas of the coastal zone require map scales larger than 1:24,000.