Maps and Photographs 



Introduction 



Maps and aerial photographs can provide a wealth of useful information 

 for the interpretation of geologic coastal processes and evolution. Maps and 

 photographs can reveal details on: 



• Long-term and short-term advance or retreat of the shore. 



• Longshore movement of sediments. 



• The impact of storms, including breaches of barrier islands, overwash, 

 and changes in inlets, vegetation, and dunes. 



• Problems of siltation of tidal inlets, river mouths, estuaries, and 

 harbors. 



• Human impacts caused by construction or dredging. 



• Compliance with permits. 



• Biological condition of wetlands and estuaries. 



For example, the geometry of the coastline in the vicinity of headlands, inlets 

 and streams, and man-made structures is one key to assessing the dispersal of 

 the products of coastal erosion and sediments supplied by rivers (Figure 41). 



Large sets of historical aerial photographs and maps have been used to 

 interpret regional geomorphic changes of coastal South Carolina (Anders, 

 Reed, and Meisburger 1990), northern New Jersey (Gorman, Reed, and 

 Stauble 1993), and the Kings Bay area of Georgia and Florida (Kraus and 

 Gorman 1993) (Figure 42). Using detailed historic data, Dolan and Hayden 

 (1983) were able to conclude that shore processes and landforms assume 

 systematic, as opposed to random, patterns both along and across the coast. 

 They found that large storms caused severe erosion in the same locations as 

 previous storms of lower intensity. Long-term erosion rates have been 

 examined even over large areas, although the quality and distribution of 

 historic maps is spotty (Dolan, Hayden, and May 1983). May and Britsch 

 (1987) examined the effects of natural and human-induced wetland losses in 

 the Mississippi Delta. 



Historical shoreline change mapping 



The use of maps and aerial photographs to determine historical changes in 

 shoreline position is increasing rapidly. Analyzing existing maps does not 

 require extensive field time or expensive equipment, and therefore often 

 provides valuable information at an economical price. This section 

 summarizes the interpretation of water line on photographs and maps and 

 corrections needed to convert historic maps to contemporary projections and 

 coordinate systems. 



Chapter 5 Analysis and Interpretation of Coastal Data 



105 



