North Chandeleur Island, Gulf Side Transects

The U.S. Geological Survey (USGS), in cooperation with the Coastal Research Laboratory in the Department of Geology and Geophysics at the University of New Orleans (UNO) and the Center for Coastal Energy and Environmental Resources at Louisiana State University (LSU), is investigating the processes of coastal erosion in Louisiana (Sallenger and others, 1987; Sallenger and Williams 1989; Penland and others, 1992).
Building on the USGS Louisiana Barrier Island Study (Williams and others, 1992), this data layer depicts the shore-normal transects that were used to measure shoreline change.
The methods and transects used by McBride and others (1992) were used to insure data compatibility of the new measurements and analysis.
To evaluate change in the shoreline position, shore-normal transects were constructed at approximately 15-second intervals of longitude or latitude depending on shoreline orientation. Isles Dernieres, Bayou Lafourche and Plaquemines barrier systems (east-west shroelines) were analyzed using 15-second (about 404 m) intervals of longitude, while the Chandeleur Islands (north-south shorelines) were examined by using 15-second (about 462 m) intervals of latitude. Measurements of shoreline movement and change in island width were taken along transects perpendicular to the composite shoreline trend. Average rates of movement and area change were calculated by dividing absolute measurements by elapsed time (year, month, and day - where available.) Shoreline change maps were procuded to determine the spatial and temporal distribution of shoreline movement (magnitude, direction, and rate of change) and document geomorphologic evolution. (McBride and others, 1992).