Winter 1999 National Data Request

(1997 Study Units)

Guidelines for preparing Ground Water GIS Coverages for National Synthesis

Released 2/8/99; Revised 3/2/99; 3/3/99

Purpose

Timetable

Scope

National synthesis needs the study units to submit their polygon coverages showing the SUS and LUS study boundaries. Each polygon coverage can be made up of a single polygon or many discontiguous polygons. Please code the polygon coverage so that any polygon within the ground water study has a valid SUCODE. Any polygon NOT included in the ground water study should have an empty SUCODE. Please code the "null polygon" as being outside the study. Please use the standard netcodes described in the 1997 data dictionary. Use lowercase letters for SUCODE.

National synthesis does not need the study units to submit point coverages showing the locations of the ground water sampling sites. We can generate point coverages showing the ground water sampling sites using information in the "sites.SUID" file. The study units do need to make sure that the ground-water information in the "sites," "netdes," and "netsite" network tables is correct.

In some cases, a study unit might have planned studies, but may not have selected any sampling sites yet. We still are interested in interim coverages of the geographic extent of these proposed studies, even if the studies might be dropped later on. If a study definitely has been dropped, sending the boundary coverage is not necessary, but please inform us that it has been dropped.

If you responded to the "advance request" for ground water GIS data or to the request by the Pesticides National Synthesis for IFS basins and ground water studies (November 1998), and, if your coverages follow the guidelines described here, you do not need to resubmit them. If the coverages do not follow these guidelines, YOU MUST RESUBMIT THEM. If in doubt, resubmit!

We strongly recommend that you use USGS metadata tools to create your documentation files. Here is an EXAMPLE of METADATA for a fictitious ground water polygon coverage.

Circular 1112 by Gilliom and others contains a description of ground water study design, SUS well selection strategy, the selection of land use studies and LUS well selection strategy. Specific information also can be obtained from your study unit Ground-Water Specialist. Please consult with your study unit Ground-Water Specialist on any questions you have regarding the ground-water study design, especially when preparing metadata. The Ground-Water Specialist is a good candidate for co-author/colleague reviewer of the metadata.

Please submit the following:

1. The polygon coverage that delineates the entire areal extent of the hydrogeologic unit defined for study, which is, in most cases, the subunit survey boundary (SUS). This boundary includes the full range of land uses, not only the targeted land use. For example, for a subunit survey, an agricultural land use study of vineyards, and an agricultural land use study of almonds in the eastern alluvial fans-San Joaquin Valley, submit the polygon coverage that represents the entire eastern alluvial fans area--the boundary of the overall area considered. One polygon coverage would represent the overall boundary of the SUS and both LUSs. One metadata file would accompany the coverage, but the file would describe all three networks and how the wells were selected for each network. If a land use study is not nested within one of the subunit surveys, submit a separate coverage representing the overall boundary of the hydrolgeologic unit within which the LUS is located and metadata for that coverage.

   Please DO NOT submit a "simplified" version of the coverage (clip coverage), such as a rectangular boundary or buffer around the maximum extent of the well locations.

2. The polygon coverage that delineates the targeted land use (LUS) within the overall area described in #1. Continuing the example from #1, this would be one coverage of the vineyard land use that is targeted for study and a second coverage of the almonds land use that is targeted for study. The targeted land use LUS coverage(s) would be nested within the overall boundary coverage. Submit a metadata file for each targeted land use coverage. The coverage metadata should describe the relationship of the LUS to the overall boundary coverage.

   Here is an illustration showing the concept of LUS boundaries being nested within the SUS boundary. (This example contains three gif files, each about 6 KB.) (See also the map showing the location of ground-water chemistry sites in Circular 1159, p.24, for a similar example.)

   For urban land use studies, for the "targeted" coverage, please submit the coverage that results from the intersection of the areal extent of the aquifer being studied with the residential/commercial land use (minus transportation and industrial land use), provided that the wells were located to achieve at least 75 percent new residential/commercial land use. This is the coverage output from SHRINK.AML that is named "buf75". Please do not submit the input study area to SHRINK.AML or the "buf75s" coverage that is the one normally used for random site selection. For questions about the urban land use coverages, please contact Curtis Price (cprice) or Paul Squillace (pjsquill).

   Please DO NOT submit a "simplified" version of the coverage (clip coverage), such as a rectangular boundary or buffer around the maximum extent of the well locations.

3. The polygon coverage of "locally improved" land use data, if available, for the study unit or for the ground water study area. If you are using a source of land use data that is different from the Anderson Level II categories (GIRAS) updated with 1990 population, please submit the "improved" coverage. The improved land use coverage should include all land use categories, not just those targeted for study. If you are using the Anderson Level II land use categories updated with 1990 population, you do not need to submit anything beyond what is requested in #2.

• COVERAGE NAMING CONVENTIONS:

  Please use the standard netcodes described in the 1997 data dictionary. Please cross-check the coverage names with the network tables to ensure that the netcodes are consistent. For example, if the netcode for a cropland LUS is luscr1, do not name the coverage LUSAG1 or LUSAG or LUSCR. Name it LUSCR1_BND or LUSCR1_TRG (see below).

  • Overall boundary: NETCODE_BND

    Please name each overall ground water study boundary coverage according to the corresponding NETCODE--for example, if the netcode is SUS1, name the polygon coverage SUS1_BND. If the overall boundary describes both an SUS and an LUS, name the coverage for the SUS. If the boundary describes a land use study that is not nested within the SUS boundary, and if the netcode is LUSCR1, name the polygon coverage LUSCR1_BND. If the coverage does not describe an SUS, but describes more than one LUS, name the coverage for one of the LUSs and indicate this in the coverage documentation. Please do not combine netcodes in the coverage name.

  • Targeted land use: NETCODE_TRG

    Please name each targeted land use coverage according to the NETCODE of the LUS--for example, LUSCR1_TRG or LUSRC1_TRG.

  • Improved land use: SUID_ILU or NETCODE_ILU.

    Please name the improved land use coverage using the 4-letter study unit abbreviation if the coverage applies to the entire study unit or LUS NETCODE if the coverage applies only to the LUS.

• PROJECTION PARAMETERS:

  Except for COOK and OAHU, please use the national projection parameters, with central meridian at -96 and North American Datum of 1927 (NAD27):

        PROJECTION ALBERS
        UNITS METERS
        DATUM NAD27 
        PARAMETERS  
        29 30 00    
        45 30 00    
        -96 00 00   
        23 00 00    
        0.0         
        0.0
    

  The projection parameters for COOK are:

        PROJECTION ALBERS
        UNITS METERS
        DATUM NAD83
        PARAMETERS
        55 00 00
        65 00 00
        -154 00 00
        50 00 00
        0.0
        0.0 
         

  The projection parameters for OAHU are:

        PROJECTION ALBERS
        UNITS METERS
        DATUM NAD83
        PARAMETERS
        08 00 00
        18 00 00
        -157 00 00
        00 00 00
        0.0
        0.0 
         

• POLYGON ATTRIBUTE TABLE TEMPLATES:
  • Overall boundary:

    Minimum required items:
           
         AREA           4 12 F 3  
         PERIMETER      4 12 F 3  
         SUSX_BND#      4  5 B    
         SUSX_BND-ID    4  5 B    
         SUCODE        12 12 C    Please enter SUCODE as lower case.
      

  • Targeted land use:

    Minimum required items:
         AREA           4 12 F 3  
         PERIMETER      4 12 F 3  
         LUSX_TRG#      4  5 B    
         LUSX_TRG-ID    4  5 B    
         SUCODE        12 12 C    Please enter SUCODE as lower case.
      

  • Improved land use:

        Minimum required items:
         AREA           4  12 F 3  
         PERIMETER      4  12 F 3  
         SUID_ILU#      4   5 B    
         SUID_ILU-ID    4   5 B    
         LUCODE         2   2 I
           
        Optional item:
         LUDESC         20 20 C
      

    We realize that people might have a variety of source material for improved land use coverages, but we will benefit if everyone tries to use a consistent item name and definition for land use code (LUCODE,2,2,I). If you cannot convert your data to this format, we will accept other definitions as long as you explain everything in the coverage documentation.

• DOCUMENTATION:

  The coverage documentation must STAND BY ITSELF--that is, people in National Synthesis should be able to use the coverage documentation to answer basic questions about the ground water network design without having to go back to design studies and other supporting documents. We have learned from experience that many of the metadata files give only sketchy information about the ground water network design and how the wells were selected. This forces us to do a lot of "detective work" to try to figure out what is going on. Many times this results in questions back to the study unit. Please help avoid the need for this by including detailed information about the ground water network and well selection process in the coverage metadata files. The study unit Ground-Water Specialist should help prepare the metadata or at least should review it. Thanks.

  Here is an EXAMPLE of METADATA for a fictitious ground water study.

  Please explain in the documentation how the coverage was used in selecting the well locations and other unique features of the study design. Please describe the process/criteria for selecting the wells and what source coverages (e.g., geology, physiography, hydrology, and so forth) were intersected to derive the study boundary. If some wells had to be resampled, please explain why so that the data analysts can determine which data they want to use. Please record information about what type of land use is being studied, what crop types or urban areas are involved, and so forth. Please explain what netcodes go with each boundary coverage, especially if one boundary describes more than one netcode.

  Please verify that the ground water sampling sites are located within the ground water study areas as defined by the GIS coverages. If some of the sites are located outside the boundary of the corresponding study area, please determine whether the boundary of the study area needs to be changed or whether the coordinates of the station need to be verified. If the GIS coverage and site location are correct, but a site still falls outside of the GIS boundary, then the documentation for the boundary coverage should explain why this occurs. For example, the documentation could state that the site was verified in the field to be sampling the correct location and the correct aquifer.

  If you prepare a "master" metadata file and use a copy of this file as the start for the metadata for each specific data set, please remember to tailor each succeeding file to the particular data set being described. If references to the first data set remain in the succeeding metadata files, the metadata doesn't make any sense.

  Please prepare an ASCII file of FGDC-compliant metadata to describe each coverage. See metadata tools. Name the metadata file COVERNAME.met.

• CHECK ARC/INFO COVERAGES:

  Please verify that the required items (i.e., SUCODE) and their values are present in the coverage .pat file.

  Please code each polygon coverage so that any polygon within the ground water study has a valid lowercase SUCODE and so that any polygon NOT included in the ground water study has a BLANK SUCODE. Polygons that should be coded blank for SUCODE include the universe polygon and any interior polygons that are "cut out" of the ground water study. The coverage may be composed of discontiguous polygons.

  Make sure ARC datasets are complete and consistent. You can use the CHECKDATA.AML. Please use ARC/INFO version 7 workspace naming conventions.

• CHECK METADATA:

  Please ensure that your ASCII metadata is "FGDC-compliant" by checking it with Peter Schweitzer's metadata parser (mp). Please use mp version 2.2.4 or later so that the metadata conforms to the content standard for digital geospatial metadata revised June 1998.

  A front-end to mp (FGDCMETA) is one of the USGS metadata tools.

  Please replace the default information generated as a template from the tool called "FGDCMETA" with information specific to your data sets.

  Please send one ASCII metadata file for each coverage. Here is an example of metadata for a GW GIS polygon coverage.

• SUBMIT COVERAGES AND METADATA:

  Copy SUSX_BND, LUSX_BND, LUSX_TRG, SUID_ILU/LUSX_ILU/SUSX_ILU coverages and ASCII metadata files into an empty directory, cd to that directory, and tar and compress (gzip) the entire directory.

  The gzip and tar programs can be downloaded from the USGS ArcInfo Enhancement Patch.

  Make the .tar file available in your anonymous ftp area:

            tar -cf - * | gzip -c > /var/ftp/pub/suidgw.tgz
  
        suid = study-unit abbreviation
    

  Please e-mail Kerie Hitt (kjhitt) with your IP address when the file is available. Please include in your email any other explanatory material you think is necessary for us to understand your submission. Thank you.