Figure 16.1: An example of georeferencing using the "rubber sheet" approach is shown here. Map (A) is the scanned ungeoreferenced historic T-Sheet # 649 from 1857. Known points (e.g. #1-5) of latitude (Lat) and longitude (Lon) are visible on this map. Using the points of latitude and longitude (Table), this map is georeferenced resulting in a new rectified map (B). Areas of the rectified map B can now be compared with other rectified and georeferenced images. The box in (B) has been enlarged and compared with the same area from a 1928 chart (C vs D). Areas of change, or no change, can then be identified.

Figure 16.2: The State of Florida is shown above and the greater Everglades ecosystem in south Florida is enlarged below. Inset boxes give the approximate positions, and figure numbers, for the remaining figures in this chapter.

Figure 16.3: Shown is an region on the southwestern shore of Lake Okeechobee. The geo-referenced 1928 T-sheet (#4128) is draped over the 2004 DOQQs. In 1928, Observation Island, was in fact, an island. Today it is surrounded by extensive marshes that are clearly visible in the 2004 aerial photography. (Scale 1:50,000)

Figure 16.4: This figure shows two nearby regions of Sanibel and North Captiva Islands on Florida's west coast. Geo-referenced charts from 1859 are superimposed on the 2004 baseline aerial images. Major changes are clearly visible between times in the upper panel depicting North Captiva Island. Redfish Pass (lower arrow) was clearly closed in 1859. The upper black arrow points to a breech in the island that was caused by storm overwash and erosion during the passage of Hurricane Charley in August 2004. The estuarine shorelines (black arrows in lower panel) of Sanibel Island, 15km to the southeast, have undergone little change. (Scale 1:50,000)

Figure 16.5: This figure shows an area in the northern 10,000 Islands. Chart T-1836 from 1888 is overlain onto 2004 aerial photographs. Positions of shoals and reefs (white arrows) and mangrove forest shorelines (black arrows) have changed little in the 116 year interval. (Scale 1:24,000)

Figure 16.6: This figure shows an area in the southern 10,000 Islands at the mouth of the Shark River. Chart T-1903 from 1889 is overlain onto 2004 aerial photographs. Major erosion and coastal set-back of the mangrove islands is clearly evident. Upper line is 250m and the lower white line 500m. (Scale 1:24,000)

Figure 16.7: This figure shows a region of south central Cape Sable. The 1857 T-sheet (#649) is overlain on 2004 aerial photographs. The 1857 shoreline has been digitised and appears as a bold black line (dashed arrow). The symbols on the chart clearly delineated mangrove forest (solid white arrows) from marsh (blue arrows). (Scale 1:24,000)

Figure 16.8: This figure shows the same area as in Figure 16.7. Here however chart T-4460, based on 1928 air photos, is overlain on the 2004 aerials. Major changes are readily apparent with marsh habitats in 1928 becoming open water (blue arrows) or mangrove forest (white arrows). The dashed white arrow points to two canals constructed in the early 1920s. (Scale 1:24,000)

Figure 16.9: A small area of southeastern Whitewater Bay is shown here at six points in time. Two small mangrove islands and a narrow mangrove forest peninsula are indicated in 1928. The two islands can be found through 1987, however between 1987 and 2004 they have disappeared. The mangrove peninsula shows a steady erosion and decrease in size over the entire time period.