TN
GIS
Data Collections

Frequently Accessed Data Layers

A collection of commonly used GIS datasets for Tennessee.  Most data are maintained in Tennessee State Plane, NAD83, Units Feet, to enable overlay and integration functions, and are organized by theme.

These data sets are derived from the U.S. Census Bureau's 2000 Redistricting versionof the TIGER line files. The population data associated or joined with these files are derived from the Census 2000 Redistricting Data (P.L. 94-171) Summary File. The dataincludes total and voting age population by racial category at the county, city, and block level geography. Other planimetric layers are also included. 

The Digital Raster Graphic (DRG) is a raster image of a scanned USGS topographic map excluding the collar information. The source maps for DRGs were georeferenced to the UTM grid, but DRG images for Tennessee are available in Tennessee State Plane, NAD83, feet. A DRG is useful as a source or background layer in a GIS, as a means to perform quality assurance on other digital products, and as a source for the collection and revision of DLG data. DRG's can also be merged with other digital data, e.g. DEM's or DOQ's, to produce a hybrid digital file.
Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection or to a geographic coordinate system. The grid cells are spaced at regular intervals along south to north profiles that are ordered from west to east. The U.S. Geological Survey (USGS) produces five primary types of elevation data: 7.5-minute DEM, 30-minute DEM, 1-degree DEM, 7.5-minute Alaska DEM, and 15-minute Alaska DEM.

Orthophotos combine the image characteristics of a photograph with the geometric qualities of a map. The primary digital orthophotoquad (DOQ) is a 1-meter ground resolution, quarter-quadrangle (3.75-minutes of latitude by 3.75-minutes of longitude) image cast on the Universal Transverse Mercator Projection (UTM) on the North American Datum of 1983 (NAD83).

Land Use/Land Cover

National Land Cover Database 2011 (NLCD 2011) is the most recent national land cover product created by the Multi-Resolution Land Characteristics (MRLC) Consortium. NLCD 2011 provides - for the first time - the capability to assess wall-to-wall, spatially explicit, national land cover changes and trends across the United States from 2001 to 2011. As with two previous NLCD land cover products NLCD 2011 keeps the same 16-class land cover classification scheme that has been applied consistently across the United States at a spatial resolution of 30 meters. NLCD 2011 is based primarily on a decision-tree classification of circa 2011 Landsat satellite data. The data has been clipped to Tennessee.
‚ÄčLidar (also written LIDAR or LiDAR) is a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light. Although thought by some to be an acronym of Light Detection And Ranging, the term lidar was actually created as a portmanteau of "light" and "radar." (http://en.wikipedia.org/wiki/Lidar)
Lidar is popularly used as a technology to make high-resolution maps, with applications in geomatics,archaeology, geography, geology, geomorphology, seismology, forestry, remote sensing, atmospheric physics, airborne laser swath mapping (ALSM), laser altimetry, and contour mapping. (http://en.wikipedia.org/wiki/Lidar)
This statewide STATSGO generalized soils coverage was provided by the National Resources Conservation Service (NRCS).  The coverage is in ArcView shapefile format and has been compressed with WinZip.

Water

This statewide watershed coverage (12 digit HUC)  was provided by the Natural Resources Conservation Service (NRCS).  The coverage is in ArcView shapefile format and  has been compressed with WinZip.  Readme and draft metadata files are included in the zipped file. 

Wetlands

These wetland data were derived from USFWS National Wetlands Inventory maps.  These maps were digitized by the Tennessee Wildlife Resources Agency from NWI maps on stable based mylar.  NWI maps in Tennessee were created from high altitude color infrared photography at a scale of 1:58,000 or black and white photography at a scale of 1:80,000.  Photography dates range from the mid-1970s to the mid-1980's. The 1:24k NWI digital quad maps were joined and clipped by county boundaries in ArcInfo and exported to create Arc Export files (.e00).   The export files were then compressed with WinZip.