February 5, 2009

In Reply Refer To:
Mail Stop 411


SUBJECT: Establishment of a National Policy to Archive Surface-Geophysical Data

The U. S. Geological Survey (USGS) collects surface-geophysical data as part of many water-resource investigations. At present, there is no standardized format for storing digital surface-geophysical data and there is no readily available means to store the data in the National Water Information System (NWIS). The purpose of this memorandum is to provide policy and guidance for archiving surface-geophysical data to preserve them for future review and use.

This surface-geophysical data archive policy is in accordance with USGS policy that states that all field notes, measurements, and observations shall be archived indefinitely (Hubbard, 1992). The fundamental purpose of the archive is to store original data, record the unique details of the data collection, and document the hydrologic conditions under which the data were collected. Through this archive policy, surface-geophysical data and metadata will be readily accessible for future research, analyses, reinterpretation, and reproducibility testing. Each USGS Water Science Center (WSC) collecting surface-geophysical data must have a written policy for data management and permanent file archiving procedures. This policy should be documented in the Center’s Data-Management Plan and Archiving Plan, both of which are a necessary part of the Center’s overall Ground-Water Quality Assurance Plan (see Brunett and others, 1997 for details). The Archive Plan must be consistent with WRD's scientific records management policy and applicable records disposition schedules (http://water.usgs.gov/usgs/srm/).

As more surface-geophysical data collection methods become digital, the ability to archive data is facilitated. Any electronic files created with a surface-geophysical survey must be permanently archived along with all paper field notes. Field notes should document the date and time of field collection, along with the names of all electronic files. Paper copies of maps, sketches, and raw data should be electronically scanned and saved. When possible, proprietary binary files should be exported to ASCII format. All data that cannot be converted to ASCII format should be archived in the original binary format along with versions of the software used for viewing, processing, and (or) displaying the data. In addition, data that are displayed in profiles or plots should be stored in graphic file or printable-document format (pdf). Although most data are digital, some analog data are still collected. This archive policy requires that analog data be “digitized” by typing results into a digital file and archived for future use. Examples of analog data include manually recorded instrument readings, such as (but not limited to) data from electromagnetic induction or gravity meters. If it is infeasible to digitize the results, the analog charts or recorded information should be archived as paper files or pdf files.

Information critical to each data set should be preserved along with the raw data. Mandatory elements for archiving surface-geophysical data are listed in table 1 and are compatible with NWIS header information. Elements critical to specific surface-geophysical methods are listed in table 2. Because new surface-geophysical methods and equipment are continually being developed, the list of equipment in table 2 is not exhaustive and should be considered a guideline for each Center’s Ground Water Quality Assurance Plan, which includes a surface-geophysical archive plan. The surface-geophysical archive plan should detail the following critical elements:

Table 1: Summarizes the mandatory elements that should be archived with surface-geophysical data in an ASCII text file (http://water.usgs.gov/usgs/ogw/bgas/surface_archiving/Table1.pdf).

Table 2: Summarizes the specific information that should be archived for representative surface-geophysical equipment (http://water.usgs.gov/usgs/ogw/bgas/surface_archiving/Table2.pdf).

The Regional Ground-Water Specialists are to act on behalf of the Office of Ground Water (OGW) to review the surface-geophysical data archives of the Water Science Centers during technical reviews. Adherence to systematic backup and archive procedures for surface-geophysical data is a responsibility of Water Science Center staff and management. Proper archiving of the data will ensure data will be available for support of published reports, future scientific investigations, and data requests from the public.

If you have any questions or comments about the policies and guidance in this memo, please contact John W. Lane, Chief, OGW Branch of Geophysics, at jwlane@usgs.gov. Additional information, including an editable spreadsheet of mandatory elements, is at http://water.usgs.gov/usgs/ogw/bgas/surface_archiving/

References cited
Brunett, J.O., Barber, N.L, Burns, A.W., Fogelman, R.P., Gilles, D.C., Lidwin, R.A, and Mack, T.J., 1997, A quality-assurance plan for District ground-water activities of the U. S. Geological Survey: U. S. Geological Survey Open-File Report 97-11, 44 p.

Hubbard, E.F., 1992, Policy recommendations for management and retention of hydrologic data of the U. S. Geological Survey: U. S. Geological Survey Open-File Report 92-56, 32 p.

William M. Alley /s/
Chief, Office of Ground Water

Distribution: A, B, DC, S, OGW, Regional and Water Science Center Ground-Water Specialists