MORPHOLOGIC CHANGES OVER THE PAST 50 YEARS
Analysis of geomorphic change and of shoreline adjustments over the past 50 years indicates that
Sebastian Inlet has responded to both natural factors and engineering activities (Fig. 6). To quantify
the inlet changes in the long-term data were documented through historical aerial surveys and
shorter-term field surveys of inlet morphology. Annual to semi-annual beach profiles and
topographic surveys of the study area were collected from the summer of 1989 to the summer of
2000. These consisted of high-resolution topographic surveys of the ebb shoal, flood shoal, sand
trap, and beach profiles tied in with submerged survey transects every kilometer along the shoreface.
Shoreline change
An extensive search for historical aerial photography was performed for the study area, returning
36 aerial surveys between February 1943 and July 2000. These photosets are variable with respect
to spatial resolution, study area coverage, size, and quality. In general, only photographs having a
spatial resolution of 1.5 m or better were retained for the study. The 23 dates selected for analysis
had a minimum approximate scale of 1:25000 and covered at least one-third of the study area. Each
photo was exported to a Tagged Image Format (TIF) and rectified to a Florida State Plane, East
Zone projection with an NAD 1927 Datum. This projection was selected primarily because it is
compatible with most historic survey data, a well-developed flood shoal that is inter-tidal, and a
prominent submerged ebb shoal.
Two sources of ground control points (GCP's) served as projection references to rectify imagery,