Satellite image maps provide an empirical foundation for the study of the temporally dynamic and spatially complex nature of Everglades land surfaces. They help laboratory and field scientists plan instrument placement and field experiments. They provide spatial context for the interpretation of data related to Everglades research, modeling, and restoration activities. They constitute baseline data for Everglades monitoring. Several satellite image maps covering the region south of Lake Okeechobee have been distributed as USGS Miscellaneous Investigations Series publications (Jones and Thomas, 2001; Thomas and Jones, 2002). Each map (for example, fig. 1) covers the largest area possible given high-quality, mass-printing limitations for 1:100,000 scale National Mapping Accuracy Standards. Every map was designed to meet a variety of needs. For example, the first publication (fig. 2) was constructed with both scientists and the general public in mind. Driven by research requirements, the boundaries of the western sheet encompass a focus area for hydrologic modeling. The eastern sheet allows the general public to view the urban development of the Atlantic Coast adjacent to the Everglades wetlands and contains descriptions of map development and interpretation in terms that can be understood by a broad spectrum of readers. Together, these two parts serve as an intuitive backdrop for discussion of important environmental, economic, and social issues. They allow viewers to understand some of the interrelations among Everglades wetland condition and agricultural, industrial, and residential activities. Some environmental features like the impact of fires and the status of nutrient removal areas are obvious (fig. 1). Others require closer image map inspection. For example, visual comparison of the first and third maps in the series uncovers subtle, high frequency variations. Their source images were collected only 9 days apart (that is, 2/5/00 and 1/27/00, respectively). However, water level data recorded in an area of image overlap show that water levels dropped approximately 8 cm over that short period (fig. 3), creating impacts that are detected with careful examination of full-resolution renditions of the image maps.

Figure 1. A thumbnail view of the Northern Everglades image map in the series of 1:100,000 scale image maps distributed in both printed and digital forms as part of the USGS Miscellaneous Investigations Series. [larger image]

Figure 2. A mosaic of the two southern Everglades image maps in the series. While this area is printed on two 1:100,000 scale maps, the maps were combined before digital distribution. [larger image]

Figure 3. Recorded stage for one Big Cypress National Preserve station number 8. [larger image]

The creation of such information-rich satellite image maps required a great deal of research and forethought. Multivariate statistical analysis was combined with the knowledge of remote sensing physics to select a combination of satellite measurements that yields desired colors, minimizes adverse impacts of the Earth’s atmosphere on image clarity, and maximizes contrasts and information content. Image colors change as the data are transferred from digital to paper formats. Therefore, previous experience and repeated trials were used to further digitally manipulate the data to produce visually appealing, easily interpreted colors across all final image maps. Project research also developed a mathematical procedure to sharpen urban and other features by merging multiple satellite image data sets. To make the image maps as useful as possible in the field, the classroom, and the conference room, they have been made widely available in a variety of formats. Printed maps can be obtained at low cost through the U.S. Geological Survey Earth Science Information Center (1-888-ASK-USGS). In addition, following Library of Congress policies, printed image maps were scanned with sufficient resolution to reproduce them to scale without loss of information. Also, these output files were sub-sampled for other uses. Finally, one file for each map was converted to Geotiff format for use in Geographic Information Systems. Each map has been featured on the South Florida Information Access website upon publication, where all digital files are freely available (http://sofia.usgs.gov).

References

Jones, John W., and Thomas, J.C., 2001, Southern Everglades: Miscellaneous Investigations Series Map I-2742 (Eastern and Western Sections).

Thomas, J.C., and Jones, J.W., 2002, Northern Everglades. Miscellaneous Investigations Series Map I-2756.

Jones, John W., and Thomas, J.C., in review., Big Cypress – Pine Island: Miscellaneous Investigations Series Map.

Contact: John W. Jones, 521 National Center, Reston, VA 20192. Phone: 703/648-5543, Fax: 703/648-4063, email: jwjones@usgs.gov.

(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report 03-54)

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