Digital data sets that describe aquifer characteristics of the Tillman terrace and alluvial aquifer in southwestern Oklahoma

Metadata Updated: December 11, 2019

This data set consists of digital polygons of constant recharge 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. A recharge value of 2.87 inches per year was used in the ground-water flow model and in this data set. The recharge 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 recharge 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.

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Date November 8, 2004
Metadata Created Date October 10, 2019
Metadata Updated Date December 11, 2019
Reference Date(s) January 1, 1997 (publication)
Frequency Of Update notPlanned
Frequency Of Update notPlanned

Metadata Source

Harvested from DOI CKAN Harvest Source

Graphic Preview

A browse image of the four aquifer data sets.

Additional Metadata

Resource Type Dataset
Metadata Date November 8, 2004
Metadata Created Date October 10, 2019
Metadata Updated Date December 11, 2019
Reference Date(s) January 1, 1997 (publication)
Responsible Party U.S. Geological Survey (Point of Contact)
Contact Email
Access Constraints Use Constraints: The recharge polygon representing the aquifer as reported by Al-Sumait (1978) was digitized from a map published at a scale of 1:249,695. Recharge polygons representing bedrock outcrops were constructed from digital data sets by Cederstrand (1996) that were scan digitized from mylar maps at a scale of 1:250,000. The recharge polygons represented at this scale are indicative of broad, regional trends and should not be interpreted as site-specific. The recharge polygon was digitized from a paper map (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 recharge 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. Recharge probably varies considerably over the local area, and model recharge is at best an average over an area at least as large as the model grid (and probably much larger than a single cell)., Access Constraints: None.
Bbox East Long -98.9482
Bbox North Lat 34.6411
Bbox South Lat 34.1912
Bbox West Long -99.2286
Coupled Resource
Frequency Of Update notPlanned
Graphic Preview Description A browse image of the four aquifer data sets.
Graphic Preview File https://water.usgs.gov/GIS/browse/ofr96-452.gif
Graphic Preview Type GIF
Guid
Harvest Object Id 092ceaa6-cfa9-43f8-8888-70df5a86ed4c
Harvest Source Id 34ce571b-cb98-4e0b-979f-30f9ecc452c5
Harvest Source Title DOI CKAN Harvest Source
Licence 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.
Metadata Language
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester true

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