Becker, Carol J. Runkle, Donna Rea, Alan 1997 1.0 map Open-File Report 96-452 Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?ofr96-452_cond This data set consists of digital polygons of constant hydraulic conductivity values for the Tillman terrace and alluvial aquifer in southwestern Oklahoma. The Tillman terrace and alluvial aquifer encompasses the unconsolidated terrace deposits and alluvium associated with the North Fork of the Red River and the Red River in the western half of Tillman County. These sediments consist of discontinuous layers of clay, sandy clay, sand, and gravel. The aquifer extends over an area of 285 square miles and is used for irrigation and domestic purposes. Granite and the Hennessey Formation outcrop in northern parts of the aquifer where alluvial deposits are absent. These outcrops were included as part of the aquifer in a thesis in which the ground-water flow in the aquifer was modeled. An average hydraulic conductivity value of 92.5 feet per day was used for both the terrace and alluvial deposits in this data set and was reported in the thesis. The hydraulic conductivity polygons were derived from two sources. The outer polygon representing the outer shell of a model grid for a ground-water flow model of the Tillman terrace and alluvial aquifer was digitized from a paper map in a thesis at a scale of 1:249,695. Polygons and lines representing geologic contacts were extracted from a published digital surficial geology data set based on a scale of 1:250,000. Small polygons along the eastern boundary of the aquifer were created when the outer polygon of the model grid and the geology polygons and lines were combined. These small polygons represent geologic units other than the Tillman terrace and alluvial aquifer within the model grid. Three small polygons representing outcrops of granite and the Hennessey Formation in the northern parts of the aquifer also were extracted from the digital surficial geology data set. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data. This data set was created for a project to develop data sets to support ground-water vulnerability analysis. The objective was to create and document a digital geospatial data set from a published report or map, or existing digital geospatial data sets that could be used in ground-water vulnerability analysis. Introduction -- This data set consists of digital polygons of constant hydraulic conductivity values for the Tillman terrace and alluvial aquifer in southwestern Oklahoma. The ground-water flow model of the Tillman terrace and alluvial aquifer in a thesis by Al-Sumait (1978) encompasses the unconsolidated terrace deposits and alluvium associated with the North Fork of the Red River and the Red River in the western half of Tillman County. These sediments consist of discontinuous layers of clay, sandy clay, sand, and gravel (Al-Sumait, 1978). The aquifer extends over an area of 285 square miles and is used for irrigation and domestic purposes. Granite and the Hennessey Formation outcrop in northern parts of the aquifer where alluvial deposits are absent. These outcrops were modeled by Al-Sumait (1978) as part of the aquifer. The term coefficient of permeability is used by Al-Sumait (1978) when referring to hydraulic conductivity. Hydraulic conductivity is a more accepted term and is used in this report. As reported by Al-Sumait (1978, p. 15) the hydraulic conductivity value for the terrace deposits is 691 gallons per day per foot squared (or 92.59 feet per day) and the hydraulic conductivity value for the alluvium is 689 gallons per day per foot squared (or 92.33 feet per day). An average hydraulic conductivity value of 92.5 feet per day was used for both the terrace deposits and alluvium in this data set. A value of -99999 was assigned to polygons representing geologic units other than the aquifer, to indicate the hydraulic conductivity is not known. Al-Sumait (1978) used a quarter-mile grid of varying hydraulic conductivity values as input to the ground-water flow model for the aquifer. The hydraulic conductivity polygons were derived from two sources. The outer polygon was digitized from a paper map in the thesis, "A computer ground-water model for the Tillman alluvium in Tillman County, Oklahoma," by Al-Sumait (1978, p. 17, fig. 4) and is based on a scale of 1:249,695. This outer polygon represents the outer shell of the model grid and also is shown in the ground-water modeling report by Kent and Naney (1978, p. 9, fig.2). Polygons and lines representing geologic contacts were extracted from a digital surficial geology data set (Cederstrand, 1996) based on a scale of 1:250,000. Small polygons along the eastern boundary of the aquifer were created when the outer polygon of the model grid and the geology polygons and lines were combined. These small polygons represent geologic units other than the Tillman terrace and alluvial aquifer within the model grid. Three small polygons representing outcrops of granite and the Hennessey Formation in the northern parts of the aquifer also were extracted from the digital surficial geology data set (Cederstrand, 1996). Digital Line Graph (DLG) format requires numbers to be stored as integers. Therefore, the hydraulic conductivity in feet per day was multiplied by 10 and stored in the digital data sets as tenths of a foot per day. For example 92.5 feet per day was multiplied by 10 and stored in the digital data sets as 925 tenths of a foot per day. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. The hydraulic conductivity and recharge are closely interrelated. As long as these two model inputs are in balance the model has a small mean residual; it represents the natural system numerically. If the hydraulic conductivity is accurately known, the model can be used to accurately determine recharge. Likewise, if the hydraulic conductivity is poorly known, then the recharge will be poorly determined. Therefore, values of hydraulic conductivity used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data. In most aquifers, hydraulic conductivity measurements made in wells or in cores will range over several orders of magnitude, even over short horizontal and vertical distances. Hydraulic conductivity values derived from ground-water flow models represent areal generalizations and do not reflect the large local variance in well or core measurements. Reviews Applied to Data -- This electronic report was subjected to the same review standard that applies to all U.S. Geological Survey reports. Reviewers were asked to check the topological consistency, tolerances, attribute frequencies and statistics, projection, and geographic extent. Reviewers were given digital data sets and paper plots for checking against the source maps to verify the linework and attributes. The reviewers checked the metadata and a_readme.1st files for completeness and accuracy. Related Spatial and Tabular Data Sets -- This data set is one of four digital map data sets being published together for this aquifer. The four data sets are: > aqbound - aquifer boundaries > cond - hydraulic conductivity > recharg - aquifer recharge > wlelev - water-level elevation contours Digital map data sets of the Oklahoma surficial geology digitized from 1:250,000-scale maps (or 1:125,000-scale maps for the three Oklahoma panhandle counties) are published separately. Other References Cited -- Al-Sumait, A.J., 1978, A computer ground-water model for the Tillman alluvium in Tillman County, Oklahoma: Stillwater, OK, Oklahoma State University, master's thesis, 152 p., 48 figs. Cederstrand, J.R., 1996, Digital geologic map of Lawton quadrangle, southwestern Oklahoma: U.S. Geological Survey Open-File Report 96-376, scale 1:250,000, 3 diskettes. (Available in nonproprietary and ARC/INFO formats.) URL:http://wwwok.cr.usgs.gov/gis/geology/index.html Environmental Systems Research Institute, Inc. (ESRI), 1995, ARC/INFO Command Reference, ARC/INFO On-line manuals: Redlands, CA. Kent, D.C. and Naney, J.W., 1978, Results of computer modeling of alluvium and terrace deposits in western Tillman County and along the Washita River, southwestern Oklahoma, for water supply capability: Stillwater, OK, final report submitted to the Oklahoma Water Resources Board, administrative report by Oklahoma State University and Scientific and Education Administration, 52 p., 35 figs. Notes -- Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. 1978 publication date Complete None planned -99.2286 -98.9482 34.6411 34.1912 none ground-water vulnerability groundwater vulnerability aquifers ground water groundwater Tillman terrace and alluvial aquifer Tillman terrace aquifer Tillman aquifer Tillman alluvial aquifer Tillman alluvial and terrace aquifer terrace aquifer alluvial aquifer alluvium terrace deposit alluvial deposit hydraulic conductivity permeability coefficent of permeability permeability coefficent inlandWaters none southwestern Oklahoma None. The hydraulic conductivity polygon representing the Tillman terrace and alluvial aquifer as reported by Al-Sumait (1978, p. 17, fig. 4) was digitized from a map published at a scale of 1:249,695. Hydraulic conductivity polygons representing granite and Hennessey Formation were constructed from digital data sets by Cederstrand (1996) that were scan digitized from mylar maps at a scale of 1:250,000. The hydraulic conductivity polygons represented at this scale are indicative of broad, regional trends and should not be interpreted as site-specific. The hydraulic conductivity polygon was digitized from a paper mape (8 inches by 11 inches) with a maximum registration root-mean-squared-error (RMSE) of 0.005 map inches 0.013 map centimeters and 364 feet (111 meters) ground distance. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. The hydraulic conductivity and recharge are closely interrelated. As long as these two model inputs are in balance the model has a small mean residual; it represents the natural system numerically. If the hydraulic conductivity is accurately known, the model can be used to accurately determine recharge. Likewise, if the hydraulic conductivity is poorly known, then the recharge will be poorly determined. Therefore, values of hydraulic conductivity used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data. In most aquifers, hydraulic conductivity measurements made in wells or in cores will range over several orders of magnitude, even over short horizontal and vertical distances. Hydraulic conductivity values derived from ground-water flow models represent areal generalizations and do not reflect the large local variance in well or core measurements. Carol J. Becker U.S. Geological Survey Hydrologist mailing address

202 NW 66th St., Bldg. 7

Oklahoma City Oklahoma 73116 United States of America 1-888-275-8747 (405) 843-7712 cjbecker@usgs.gov none http://water.usgs.gov/lookup/get?OFR96-452/browse.gif A browse image of the four aquifer data sets. GIF Compilation of this data set and the associated metadata was funded under a cooperative Joint Funding Agreement between the U.S. Geological Survey and the State of Oklahoma, Office of the Secretary of Environment. Public UNCLASSIFIED None Operating System-- UNIX, ARC/INFO Version 7.0.3,(Mon Mar 13 22:21:55 PST 1995) Cederstrand, Joel R. 1996 1.0 map Open-File Report 96-376 Oklahoma City, OK U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?ofr96-452_cond Polygon and chain-node topology present. This data set includes the average hydraulic conductivity value published on page 15 for the Tillman terrace and alluvial aquifer and all the aquifer boundaries published on page 11, figure 2, and page 17, figure 4 by Al-Sumait, (1978). Lines with a value of 2 for the LSOURCE line attribute were taken from Cederstrand, (1996). None 10 meters Resolution as reported None. A tic data set was created using 1:250,000-scale U.S. Geological Survey quadrangle maps. The hydraulic conductivity polygon representing the aquifer was digitized in one session with a maximum registration root-mean-squared-error (RMSE) of 0.005 map inches (0.013 map centimeters) or 364 feet (111 meters) ground distance. 19960319 Polygons representing outcrops of bedrock were extracted from a digital surficial geology data set using the ARC/INFO command CLIP (ESRI, 1995) with a fuzzy tolerance of 32.8 feet (10 meters). 19960604 The polygons were attributed for K and lines were attributed for LSOURCE. 19960605 Vector Point 27 String 76 GT-polygon composed of chains 28 Albers Conical Equal Area 29.5 45.5 -96 23 0.0 0.0 coordinate pair 10 meters 10 meters METERS North American Datum of 1983 Geodetic Reference System 80 6378137 298.257 COND.PAT Polygon attribute table ARC/INFO - Polygon attribute table ARC/INFO - n/a n/a AREA Area of polygon in square coverage units Computed Positive real numbers n/a n/a PERIMETER Perimeter of polygon in coverage units Computed Positive real numbers n/a n/a COND# Internal feature number Computed Sequential unique positive integer n/a n/a COND-ID User-assigned feature number User-defined Integer n/a n/a K Hydraulic conductivity in tenths of a foot per day Al-Sumait (1978) 925, -99999 n/a n/a MINOR1 Blank item for DLG Calculated 0 n/a n/a MAJOR1 Hydraulic conductivity in tenths of a foot per day Al-Sumait (1978) 925, -99999 n/a n/a COND.AAT Arc attribute table ARC/INFO - Arc attribute table ARC/INFO - n/a n/a FNODE# Internal number of from-node Computed Sequential unique positive integer n/a n/a TNODE# Internal number of to-node Computed Sequential unique positive integer n/a n/a LPOLY# Internal number of poly to left of arc Computed Sequential unique positive integer n/a n/a RPOLY# Internal number of poly to right of arc Computed Sequential unique positive integer n/a n/a LENGTH Length of arc in coverage units Computed Positive real numbers n/a n/a COND# Internal feature number Computed Sequential unique positive integer n/a n/a COND-ID User-assigned feature number User-defined Integer n/a n/a LSOURCE Source of line Al-Sumait (1978), Cederstrand (1996) 1,2 n/a n/a MINOR1 Blank item for DLG Calculated 0 n/a n/a MAJOR1 Source of line Al-Sumait (1978), Cederstrand (1996) 1,2 n/a n/a Each polygon in this data set has an associated attribute, K, containing a value of hydraulic conductivity (Al-Sumait, 1978) expressed in tenths of a foot per day. For example, the hydraulic conductivity value of 92.5 feet per day is stored as a K value of 925. Polygons in this data set containing a K of -99999 represent areas where the hydraulic conductivity value of geologic units other than the aquifer is not known. K is stored in the first major code (MAJOR1) for polygons, and 0 is stored in the first minor code (MINOR1) in the Digital Line Graph (DLG) version of this data set. Each line in this digital data set has an associated attribute, LSOURCE, that contains a code to indicate the source of the line. An LSOURCE code of 1 indicates the line was digitized from Al-Sumait (1978), and an LSOURCE code of 2 indicates the line was extracted from Cederstrand (1996). LSOURCE is stored in the first major code (MAJOR1) for lines, and 0 is stored in the first minor code (MINOR1) in the Digital Line Graph (DLG) version of this data set. See overview. U.S. Geological Survey Ask USGS - Water Webserver Team mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+ofr96-452_cond Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Export Full coverage zipped 1 http://water.usgs.gov/GIS/dsdl/ofr96-452_cond.e00.gz Other DLG file format zipped 1 http://water.usgs.gov/GIS/dsdl/ofr96-452_cond.dlg.gz None. This dataset is provided by USGS as a public service. 20041108 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing

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Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+ofr96-452_cond FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998