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Scientific Investigations Map 3048

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## Gulf of Mexico Region—Highlighting Low-Lying Areas Derived from USGS Digital Elevation Data

#### By John J. Kosovich

| Abstract
In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts a color shaded relief representation of the area surrounding the Gulf of Mexico.  The first 30 feet of relief above mean sea level are displayed as brightly colored 5-foot elevation bands, which highlight low-elevation areas at a coarse spatial resolution.  Standard USGS National Elevation Dataset (NED) 1 arc-second (nominally 30-meter) digital elevation model (DEM) data are the basis for the map, which is designed to be used at a broad scale and for informational purposes only.  

The NED data were derived from the original 1:24,000-scale USGS topographic map bare-earth contours, which were converted into gridded quadrangle-based DEM tiles at a constant post spacing (grid cell size) of either 30 meters (data before the mid-1990s data) or 10 meters (mid-1990s and later data).  These individual-quadrangle DEMs were then converted to spherical coordinates (latitude/longitude decimal degrees) and edge-matched to ensure seamlessness.  Approximately one-half of the area shown on this map has DEM source data at a 30-meter resolution, with the remaining half consisting of 10-meter contour-derived DEM data or higher-resolution LIDAR data.

Areas below sea level typically are surrounded by levees or some other type of flood-control structures.

State and county boundary, hydrography, city, and road layers were modified from USGS National Atlas data downloaded in 2003.  The NED data were downloaded in 2005. | Version 1.0

Posted November 2008
-  **Map** PDF (89.9 MB) 
-  **Downloads** Directory  Contains: geospatial database. Refer to the Readme and Metadata files for more information. 
-  **Order a Print** from the USGS Store 

**For additional information contact:**          USGS Central Region Geospatial Information Office          Federal Center          Box 25286          Denver, CO 80225

Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge. |
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### Suggested citation:

Kosovich, J.J., 2008, Gulf of Mexico Region—Highlighting low-lying areas derived from USGS digital elevation data: U.S. Geological Survey Scientific Investigations Map 3048, scale 1:1,350,000.

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U.S. Department of the Interior | U.S. Geological Survey	URL: *http://pubsdata.usgs.gov/pubs/sim/3048/index.html*	Questions or Assistance: Contact USGS	Last modified: Thursday, 01-Dec-2016 17:12:12 EST