Depth to Initial Ground Water in Feet, at 1:100,000-Scale

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

Title: Depth to Initial Ground Water in Feet, at 1:100,000-Scale

Abstract:

This data represents a depiction of the Depth to Initial Ground Water for the state of Wyoming (excluding Yellowstone National Park) at a 100 meter cell resolution, 1:100,000 scale. The data was created by using Kriging to interpolate a smooth surface between known data points obtained from the Wyoming State Engineer's Office well permit records at various years.

1. How should this data set be cited?

   Wyoming Water Resources Center, 199702, Depth to Initial Ground Water in Feet, at 1:100,000-Scale: Spatial Data and Visualization Center, Laramie, Wyoming.

   Online Links:

   • <URL:http://www.sdvc.uwyo.edu/clearinghouse/water.html>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: -111.04531329

   East_Bounding_Coordinate: -103.84002217

   North_Bounding_Coordinate: 44.99712629

   South_Bounding_Coordinate: 40.94825784

3. What does it look like?

   <URL:http://www.sdvc.uwyo.edu/images/dtw100k.gif> (gif)

   depth to ground water contours in Wyoming

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: unknown

   Ending_Date: present

   Currentness_Reference: Publication date of sources

5. What is the general form of this data set?

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

      This is a Raster data set. It contains the following raster data types:

      • Dimensions 4491 x 5862, type Grid Cell

   2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:

      Standard_Parallel: 33

      Standard_Parallel: 45

      Longitude_of_Central_Meridian: -107.5

      Latitude_of_Projection_Origin: 41

      False_Easting: 0.00000

      False_Northing: 0.00000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in METERS

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257.
      

7. How does the data set describe geographic features?

   Entity_and_Attribute_Overview:

   The lone attribute within this layer is called VALUE (the default ARC/INFO GRID name) and represents depth to initial ground-water in FEET from the land surface.

   Entity_and_Attribute_Detail_Citation: n/a

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • Wyoming Water Resources Center

2. Who also contributed to the data set?

3. To whom should users address questions about the data?

   SDVC Technical Coordinator
   Spatial Data and Visualization Center
   Box 4008 University Station
   Laramie, Wyoming 82071
   USA
   

   307-766-2532 (voice)
   itasca@uwyo.edu
   

   Hours_of_Service: 8 AM to 5 PM MST

This data was created specifically for use in the Wyoming Ground-water Vulnerability Mapping project. The data represents only depth to INITIAL ground-water and does not reflect potential water quantity or quality issues. The data is also limited to areas within Wyoming in which wells have been recently drilled.

1. From what previous works were the data drawn?

   well permit database (source 1 of 1)

   Wyoming State Engineer's Office, 1993, Well Permit Database.

   Type_of_Source_Media: AREV database (digital)

   Source_Contribution: source of depth to groundwater points

2. How were the data generated, processed, and modified?

   Date: 01-Apr-1994 (process 1 of 1)

   The well permit database was exported from AREV to ASCII text files by county. This text file included permit no., permit holder, location in Township/Range/Section/QQ, facility name, permit status, use code, priority date, yield, well depth, static water depth, main water bearing zone (mwbz) top, mwbz bottom, well diameter, county, and water district. These text files were sorted and imported into an INFO database. Any records where field types didn't match (ie a character entry such as a person's name into the integer well depth field) were discarded initially. After importing each county 84,700 unique records existed. Next the record number, township, range, section, and qq were exported to a text file and run through a fortran program called TRLL (Township Range to Lat-Long) which was created by Charles Morgan and Jesse McNellis of USGS in 1965 and updated by Dennis Grasso in 1988. This routine generates latitude and longitude values for the points from township/range descriptions. Using the GENERATE utility within ARC/INFO these records were converted to a point coverage and the original INFO file was joined using the common record number. An initial QA/QC process was then performed that deleted wells that didn't exist spatially within the county that they were permitted, wells that listed static water depth as less than 0, wells that listed a use-code as OIL, and wells with mwbz listed as greater than 3000 feet. With these routines completed, 74,370 wells remained. The next procedure removed deep wells that existed in the same quarter-quarter section as shallower wells. An automated script was used to check through each qq section marking for deletion all wells except for the shallowest within that qq leaving 30,987 wells.

   In order to not interpolate across various aquifer boundaries the wells were divided up into three categories based on geologic age of the aquifer. The three categories were Tertiary, Quaternary, and Older.

   Finally, a spherical Kriging procedure was performed to generate an estimated surface from the points in each of the three layers and they were then combined using the geologic age boundaries. The cell size used was 100 meters.

   Other methods of Kriging were evaluated, but spherical Kriging was chosen based on aesthetic and "believability" reasons by the reviewer.

   The cell size of 100 meters was chosen based on the intended scale of 1:100,000. This scale was chosen for the Wyoming Ground-Water Vulnerability Project of which this layer was a part.

3. What similar or related data should the user be aware of?

1. How well have the observations been checked?

   The Wyoming State Engineer's Office performed no reviews to their database before transferring the data to the Wyoming Water Resources Center. Final layer was reviewed by Dr. Peter Huntoon, Dept. of Geology and Geophysics, University of Wyoming. Dr. Huntoon is a respected hydro-geologist and an expert on the hydrology of Wyoming. As of 1996, no QA/QC procedures have been performed on the values within the database. Obvious errors have been removed, but some errors are sure to have remained.

2. How accurate are the geographic locations?

   Does not apply as this data is a predicted surface, generated by kriging methods.

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

   100%

5. How consistent are the relationships among the observations, including topology?

   does not apply to raster data

Are there legal restrictions on access or use of the data?

Access_Constraints: none

Use_Constraints:

The data should not be used for analysis of greater than 1:100,000 scale. The data was created from 30,987 well data points which tend to be grouped in alluvial zones. These points were selected from the 79,798 total well points. The data can be assumed to be fairly accurate in the alluvial floodplains, but should not be relied on in steep or mountainous zones. Because of a severe limitation of available data, well points from the entire Wyoming State Engineer's Office database were used regardless of age. Some depths can be assumed to have changed with time. Another potential source of error is the SEO database itself. As of 1996, no QA/QC procedures have been performed on the values within the database. Obvious errors have been removed, but some errors are sure to have remained.

1. Who distributes the data set? (Distributor 1 of 1)

   Data Manager
   Spatial Data and Visualization Center
   Box 4008 University Station
   Laramie, Wyoming 82071
   USA
   

   307-766-2751 (voice)
   n/a
   

2. What's the catalog number I need to order this data set?

3. What legal disclaimers am I supposed to read?

   The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate used described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor described above and not indirectly through other sources which may have changed the data in some way. See the Use_Constraints section of this metadata for appropriate uses/limiations of the data. The distributor makes no claims for the data's suitability for other purposes.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ARCE (Arc/Info export) (version 7.0.4)
     Network links:	ftp.sdvc.uwyo.edu or <http://www.sdvc.uwyo.edu/clearinghouse>

   • Cost to order the data:

     No fees are required for downloading the data that is on-line. Some fees may be required to cover costs of tapes if data is required on tape media.

Dates:

Last modified: 12-Aug-1998

Metadata author:

Margo Berendsen
Box 4008 University Station
Laramie, Wyoming 82071
USA

307-766-2751 (voice)
meh@uwyo.edu

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)