Figure 1. Location map showing the distribution of coastal sand barriers 

 along the Holocene Mississippi River deltaic plain. 



seen in the destruction of connmercial and residential property, the accompanying loss of 

 valuable coastal wetlands caused by the removal of protective storm barriers, and the 

 loss of fishery resources caused by intrusion of salt water into wetland nursery areas. A 

 new and comprehensive evaluation of shoreline change trends along 250 km of Louisiana's 

 barrier coastline has been made for 1922-78, using digitization of individual island areas 

 from the U.S. Coastal Survey charts dated between 1869 and 1969 and land cover maps 

 dated 1979. 



DATA ACQUISITION 



Analysis of shoreline change was based on two independent sets of data. Changes 

 in Gulf of Mexico shoreline positions were derived by the Orthogonal-Grid Mapping 

 System technique (Dolan et al. 1978). This technique produces a location of the 

 high-water line for every 100 m of shoreline, based on information that has been 

 summarized as an average rate of shoreline change over the period of data collection and 

 expressed as areas of either accretion or erosion within 5m/yr-class intervals. 



The second data set was obtained by individually digitizing the surface area of each 

 barrier island on the Louisiana coast. This method analyzed U.S. Coast and Geodetic 



15 



