The Water Resources NSDI Node is an online centralized repository of digital metadata that conforms to the Federal Geographic Data Committee (FGDC) standards.

Attachment to Water Mission Area Memorandum "Guidelines for the Release of Digital Spatial Data Sets"

Contents

SPATIAL DATA SETS

Any data set that references its data to a geographic location is a spatial data set. Data stored in the National Water Information System and all of its subsystems, or retrieved from these systems in an unaltered state are exempt from these guidelines. For purposes of these guidelines, spatial data sets are any data sets that reside in or have been processed by any spatial analytical software, such as a Geographic Information System (GIS) or an image-processing system. Examples of spatial data sets include Arc/INFO coverages, Intergraph MGE files, MapInfo MIF files, Triangular Irregular Networks, Arc/INFO GRIDS, model grids, shape files, images, and computer-aided drafting (CAD) or similar georeferenced data sets.

METADATA

A number of software programs are available to collect, manage, and validate geospatial metadata. Some programs are available for use within the Arc/INFO GIS software system, although the majority of software is intended for stand-alone use in the Windows environment. The output of a selected metadata tool should be verified for compliance with the Federal Geographic Data Committee (FGDC) metadata standard using validation software, which is available from the FGDC. The use of software that produces compliant metadata makes the documentation and advertising of Water Resources Division (WRD) data resources consistent with metadata produced by more than 90 Federal, State, local, and international organizations that participate in the FGDC-sponsored Clearinghouse activity. Available software will allow the collection of metadata in a single format that can be systematically converted within the Clearinghouse to other presentation forms, such as hypertext markup language (HTML) and standard generalized markup language (SGML). To support search and presentation of information in the Clearinghouse, users need to provide compliant FGDC metadata for each available spatial data set in either text, HTML, or SGML format to the WRD National Spatial Data Infrastructure (NSDI) Node.

RELEASE AND PUBLICATION

In most cases data sets that require release can and should be specifically identified early in project planning, ideally in the project proposal. Resources for documenting, reviewing, and releasing the identified data sets should be included in the project budget

Required Release

Two factors determine whether a data set is required to be released:

1. preservation of the scientific record, and
2. significant potential for reuse.

Data sets that contain original information not available elsewhere in the public record and not easily derivable from other public sources must be released. Examples include data sets used to make calculations for a statistical summary in a report or input to a ground-water model; if the report or model results can not be easily replicated without a data set, the data set must be released. Spatial data sets that result from digitizing interpretive analog (printed) maps and that are available for the first time in digital form should be released.

Spatial data sets that are "deliverables" for a project have high potential for reuse and, thus, must be released. Data sets that are not specific deliverables also may require release if they are derived from large amount of processing or interpretation and have an apparent value beyond that of their originating project.

Temporary or working digital spatial data sets ("Internal data sets", WRD Memorandum 94.34) are specifically excluded from the mandatory release requirement. Similarly, digital spatial data sets that are copies or minor modifications, such as those that are the result of map reprojection, map joining, or subsetting; or digital spatial data sets published elsewhere, such as 1:100,000-scale U.S. Geological Survey Digital Line Graphs or other standard USGS map series, need not be released again. Digital spatial data sets of a proprietary nature or classified for national security reasons also are exempt from release. Finally, depending on current demand for the information, digital spatial data sets that were created before Executive Order 12906 was issued in April 1994 are to be documented and released over the next few years as they can be integrated into the work schedule. Even though a data set may be exempt from mandatory release requirements, preparing compliant metadata is recommended.

In addition to being released through the WRD Node, some digital spatial data sets that contain interpretive material may also warrant release as a separate publication. This separate publication may comprise only the metadata but could include other information, such as graphics and discussions of interpretive findings, and could be arranged in a format appropriate for the specified USGS publication series. A separate publication also may discuss several related data sets, whereas a metadata file describes only one data set. USGS publication series, such as Open-File Reports, Water-Resources Investigations Reports, Digital Data Series, and Professional Papers, or outside publications may be released in print or other stable electronic media, such as CD-ROMS and diskettes. Digital spatial data sets that already have been released under another form, such as a diskette or CD-ROM Open-file Report, need not be released again, unless the data sets have been substantially modified but the metadata still must be made available through the node.

Authorship

At least one author must be named in the "Originator" field of the metadata. Authorship normally is restricted to participants who contributed substantially to creation of an original data set. For participants responsible for assembling a non-original data set, such as a digitized version of a published map, they should be credited as compilers or editors.

It is not uncommon for spatial data sets to be revised and reissued, sometimes by persons other than the original author/compiler. The supervisor of the unit that produces the revised data set shall decide authorship in such cases. In all of these situations, however, the original source or author(s) of the information must be cited. Acknowledgment of other assistance may be included in the "Data_Set_Credit" field of the metadata.

Structure

Publishing a report is a separate issue from releasing the digital spatial data set; in some cases, however, the metadata may serve as the report manuscript, usually released in the Open-File Report series. Depending on the significance of the work, the metadata may be released in any USGS publication series, including the Water-Resources Investigations Report Series, the Digital Data Series, or the Professional Paper Series.

A separate report that treats several digital spatial data sets as a collection may be prepared. The report and the data sets must be reviewed together. Each data set must stand on its own. That is, the data set and its metadata must be treated as a single logical entity; one data set corresponds to one metadata file. Each data set must have a unique USGS report series number (for example, USGS Open-File Report 97-574), so that references may readily distinguish among the individual data sets.The metadata files for each data set will indicate that the data set is part of a collection and refer back to the report. An example of such a collection of data sets in a report is USGS Open-File Report 97-574, which is available online and on diskette.

Citation

The reference to a digital spatial data set should include the name of information provider(s) publication date, title, publisher and publication series and number, access date, and the uniform resource locator (URL) as follows:

Rea, Alan, and Tortorelli, R. L., 1997, Digital-Map Grids of Mean Annual Precipitation for 1961-90, and Generalized Skew Coefficients of Annual Maximum Streamflow for Oklahoma: U.S. Geological Survey Open-File Report 97-574, accessed August 31, 1998, at URL https://water.usgs.gov/lookup/get?ofr97-574.

Note that the citation gives a persistent URL that is based on the assigned USGS report series and number. The WRD NSDI Node will support this format for the foreseeable future.

REVIEW AND APPROVAL

The digital spatial data set and its metadata must be reviewed by two colleague reviewers that are knowledgeable about GIS and spatial-data production. The key question to be answered is this: "Does the metadata accurately describe the digital spatial data set so that readers can assess its usefulness for their particular purposes?"

Because digital spatial data sets generally integrate information from several areas of expertise, it sometimes may be difficult to find reviewers that are sufficiently knowledgeable in all required subjects. In such cases, reviews may be divided among several reviewers with the appropriate expertise; for example, some reviewers would examine the construction of the data set, and others would evaluate the scientific content. If the work is non-interpretive, only two reviewers are required. There may be situations, however, where the data sets are of such scientific complexity or value that additional reviewers may be necessary. For interpretive data sets, at least one reviewer for each aspect must be from outside the author's office as shown by the flow diagram of spatial data-set review and release process in figure 1.

Colleague reviewers should not merely offer editorial comments on the metadata; they should review the data set itself to ensure that it matches the explanation in the metadata. Reviewers will have access to all source materials, if needed, but will also be free to use any other information available.

Colleague review of digital spatial data sets typically would include evaluation of positional accuracy, contextual accuracy (how the data set compares to related data sets), attribute accuracy, and topological consistency, WRD Memorandum 94.34. It is necessary that the reviewers agree that the metadata contains an accurate description of the quality of the data set.

As with all USGS colleague reviews, the comments of the reviewers and the author's responses to them are not to be released. However, the scope of the review - for example, what was checked and what tests were performed - should be noted in the metadata.

Once the author has responded to the reviewers' comments, release of non-interpretive digital spatial data sets may be approved by an appropriate Director's approving official, such as a Regional Reports Specialist, or an authorized District or Equivalent Office Chief. For interpretive digital spatial data sets, the metadata must be approved by the Regional Reports Specialist.

Criteria for approval are:

• Has the report been adequately reviewed and has the author addressed the reviewers' comments?
• Is the digital spatial data set (including transfer files and metadata) ready for delivery to the public through the WRD NSDI Node?
• Is the data set inconformance with all USGS policies regarding review, approval, and equal release of information?

Approval procedures are determined by the approving official and entered into the WRD Reports Tracking System. The name of the approving official must be given when submitting materials to the WRD NSDI Node for distribution.

WORLD WIDE WEB RELEASE THROUGH CLEARINGHOUSE

The easiest way to release a digital spatial data set is to submit the data set and its metadata to the WMA NSDI Clearinghouse Node. Instructions for submitting a digital spatial data set are available on the WRD web site. Releasing a data set on the WRD NSDI Clearinghouse Node does not preclude distribution by other means.

For more detailed guidance and examples of how to submit data sets and metadata to the WRD NSDI Node, see the WRD Web site pages on "Releasing Spatial Data Sets" at url https://water.usgs.gov/usgs/gis.

The WRD NSDI Node operates as part of the USGS Node of the NSDI. Like other parts of the USGS Node, the WRD Node stores metadata in a format suitable for searching under a standard specified by the Federal Geographic Data Committee (FGDC) and is registered with the FGDC Clearinghouse as a source for information searching. In simple terms, this means that, if the metadata is stored on the WRD Node, then anyone using the FGDC's search engine has a reasonable chance of finding it https://www.fgdc.gov/nsdi-plan/ .

In addition to serving metadata, the WRD NSDI Node also is designed to serve spatial data sets. The WRD Node is located on one of USGS's web site gateways, so transmitting data to outside users does not tie up internal USGS network resources. When a user requests a digital spatial data set, the WRD Node presents a page that briefly describes the data set, highlights a link to the metadata, lists all the available files, and explains how to retrieve each format. For example, https://water.usgs.gov/lookup/getspatial?huc2m will retrieve the "huc2m" spatial data set.

Finally, the WRD Node provides archiving capability for data sets, even when they are revised. All data sets on the WRD Node remain a permanent part of the scientific record.

A data set may be made available from a District's web site or a cooperating agency's web site rather than placing it in a node of the FGDC Clearinghouse if:

Digital spatial data sets must, at a minimum, be distributed in the Spatial Data Transfer Standard (SDTS) format; in addition, they can be distributed in "native mode,"-for example, Arc/INFO export format. Conversion procedures are available for many common GIS's. An ARCSDTS procedure is available on many WRD Arc/INFO systems, and the source code is available for other systems.

If conversion to SDTS format is not possible, USGS Policy states that data must be made available to the public in a non-proprietary format, at a minimum. Data sets in Computer Aided Drafting (CAD) or raster formats, until the SDTS profiles are complete, can be made available in a non-proprietary format; such alternate non-proprietary formats include CAD interchange (DXF) files, shapefiles, and several image formats, including TIFF and BIL images. Triangular Irregular Network data can be converted to a point data set and formatted to SDTS.

DISTRIBUTION AND ARCHIVING

Previously released versions of digital spatial data do not have to be online. Like any important files, prior versions should be saved on secure media. A contact name (a position, not a person) for an office will be given in the metadata for users who need to obtain these earlier versions. The Office of Information will be responsible for ensuring that the WRD NSDI Node will automatically take care of this when a data set on the node is updated.

Each revised digital spatial data set should be assigned an edition or version number under the Identification_Information:Citation:Edition tag of the metadata. A two-part system, such as "1.0," "1.1," or "1.2." is recommended. The version number must always be mentioned in citations.

    The Water Resources NSDI Node is an online centralized repository of digital metadata that conforms to the Federal Geographic Data Committee (FGDC) standards.