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Scientific Investigations Map 3050

State of Texas—Highlighting Low-Lying Areas Derived from USGS Digital Elevation Data

By John J. Kosovich


Thumbnail of and link to report PDF (62.6 MB)

In support of U.S. Geological Survey (USGS) disaster preparedness efforts, this map depicts a color shaded relief representation of Texas and a grayscale relief of the surrounding areas. 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) 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. The NED source data for this map consists of a mixture of 30-meter- and 10-meter-resolution DEMs.

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 2002. Shaded relief over Mexico was obtained from the USGS National Atlas.

Version 1.0

Posted November 2008

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.

Suggested citation:

Kosovich, J.J., 2008, State of Texas—Highlighting low-lying areas derived from USGS digital elevation data: U.S. Geological Survey Scientific Investigations Map 3050, scale 1:700,000.

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Last modified: Thursday, 01-Dec-2016 17:12:20 EST