Directory / (root) index.htm file:
This report contains digital data and accompanying documentation for aquifer boundaries for the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. This digital data set was compiled from a digital coverage that was created for publication of paper maps in McGrath and Dugan (1993, Water-level changes in the High Plains aquifer -- predevelopment to 1991: U.S. Geological Survey Water-Resources Investigations Report 93-4088, 53 p.) The data are not intended for use at scales larger than 1:1,000,000.
The data sets provided in this report are available in nonproprietary and ARC/INFO export file formats. (See NOTES section.) Files, except those with ".GIF" or ".GZ" extensions, are ASCII format files.
The data sets stored in the generic, public-domain Digital Line Graph (DLG-3) Version 3, Optional format have file extensions of ".DLG". Designed for data interchange, the DLG-3 format allows the simple creation of a vector polygon or line data structure. The topological linkages are explicitly encoded for node, area, and line elements. The files are composed of 8-bit ASCII characters organized into fixed logical records of 80 bytes. A detailed description of the DLG-3 Optional format may be found in the data users guide 3, Digital Line Graphs from 1:2,000,000-scale maps (U.S. Geological Survey, 1990).
The ARC/INFO export files are ASCII files that utilize a proprietary format. The "NONE" compression option was used with the ARC/INFO EXPORT command. The ARC/INFO export files have file extensions of ".E00".
The data set files have ".GZ" extensions and were compressed for distribution. These files need to be uncompressed to access the digital data. The GZIP utility is a MS_DOS executable program that will uncompress the data files. To uncompress a file, type at the MS-DOS prompt:
GUNZIP -aN AQBOUND.GZ
This command will uncompress the file and restore its original name. For example:
"AQBOUND.DLG" or "AQBOUND.E00" .
A documentation file (known as metadata) is provided for each data set. The documentation files comply with the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (Federal Geographic Data Committee, 1994). The FGDC-compliant metadata files contain detailed descriptions of the data sets, and include narrative sections that describe the procedures used to produce the data sets in digital form.
A graphic image also is provided in a Graphics Interchange Format (GIF) file. GIF files are easily displayed on a variety of computer systems that use readily available display software including Internet browser software. This image provides a simplified view of the data sets, and may be used for browsing purposes. The GIF file portrays significantly less spatial resolution and information content than the actual data sets.
No software is provided with these data sets. Users will need GIS software to use the data sets. The U.S. Geological Survey does not recommend or endorse any particular software package for use with these data sets. For some links to more information on GIS software and capabilities, see: The GIS FAQ (Frequently Asked Questions), GIS Companies on the WWW, USGS GIS Information.
This report is organized into five files and three subdirectories:
\-------||-a_notice.txt - Liability disclaimer
|-aqbound.htm - Complete documentation of the data sources
and procedures used to create the data set
in HTML format
|-aqbound.txt - Complete documentation of the data sources
and procedures used to create the data set
|-browse.gif - Browse image of the data sets in GIF format
|-index.htm - This file
|-arc_data\ - Data set in ARC/INFO export file format
|-pd_data\ - Data set in nonproprietary DLG-3 format
|-gzip\ - MS-DOS executables and related files for the
GZIP package, which is needed to uncompress
the files having a ".gz" extension
The documentation file (known as metadata) for the data sets is in 2 file formats. The documentation file with the ".txt" extention is an ASCII-text file whereas, the file with the ".htm" extention is in a HTML format that is compatable with most internet browsers. The documentation file complies with the Federal Geographic Data Committee (FGDC) Content Standards for Digital Geospatial Metadata (Federal Geographic Data Committee, 1994). The FGDC-compliant metadata file contains detailed descriptions of the data sets, and includes narrative sections describing the procedures used to produce the data sets in digital form.
The digital data are stored in decimal degrees. The projection is cast on the North American Datum of 1983. Map projection information is shown below.
Spheroid GRS80 (Geodetic Reference System 1980)
Datum NAD83 (North American Datum 1983)
Units DD (Decimal Degrees)
Use of trade names is for descriptive purposes only, and does not imply endorsement by the U.S. Government.
ARC/INFO software was used in the development of the data sets. The data sets were processed using the ARC/INFO Revision 7.0.3 software package, running on a Data General AViiON workstation. Further processing was done using ARC/INFO Revisions 7.0.4 and 7.1.1 on a SUN Enterpise 4000 running Solaris Version 2.5.1. File names in this document are enclosed in quotation marks and type set in upper case.
Environmental Systems Research Institute, Inc. (ESRI), 1997, ARC/INFO Command References, ARC/INFO Version 7.0.4 ArcDoc: Redlands, CA. [online documentation].
Federal Geographic Data Committee, 1994, Content standards for digital geospatial metadata (June 8): Federal Geographic Data Committee, Washington, D.C., 78 p.
McGrath, Timothy and Dugan, Jack T., 1993, Water-level changes in the High Plains aquifer -- predevelopment to 1991: U.S. Geological Survey Water-Resources Investigations Report 93-4088, 53 p.
Nebert, D.D., 1994, Design of the distributed spatial data library (DSDL) for the Water Resources Division: U.S. Geological Survey Open-File Report 94-327, 26 p.
U.S. Geological Survey, 1990, Digital line graphs from 1:2,000,000- scale maps, data users guide 3: U.S. Geological Survey National Mapping Program Technical Instruction, 70 p.