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

U.S. Geological Survey

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 is the basis for the map, which is designed to be used at a broad scale and for informational purposes only.

The NED data was typically 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 (pre-1990s data) or 10 meters (1990s and later data). Approximately one-half of the area shown on this map had 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.

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

Courtesy of U.S. Geological Survey.

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