Proposal for a Data Accuracy Standard for Bathymetric/Hydrographic Data

Project Title

Geospatial Positioning Accuracy Standard for Hydrographic Surveys and Nautical Chart Data.

Submitting Organization

FGDC Subcommittee on Bathymetric Data, Chaired by the National Oceanic and Atmospheric Administration, National Ocean Service, Office of the Coast Survey. 1315 Eastwest Highway, Room 6222, Silver Spring Maryland. The point of contact is Millington Lockwood, Executive Secretary of the Bathymetric Subcommittee. Phone 301-713-2777x171 email


This Standard is Part 4 of the multi-part standard for geospatial positioning. It is intended to serve the community of users who are involved with the construction and maintenance of nautical charts, hydrographic surveys, and bathymetric data bases.

This standard is based upon the recently revised International Hydrographic Organization Standard for Hydrographic Surveys as contained in the Special Publication No. 44. (SP-44). This standard is currently in the final stages of review by the international community. It is anticipated that it will be completed by July 1997. The fundamental (conceptual) aspect of this standard is that it will be able to accommodate multiple accuracy levels or "orders" of hydrographic surveys based upon the needs or requirements of potential applications.

Previous versions of this standard concentrated primarily on classifying accuracies for hydrographic surveys for the compilation of nautical charts and utilized a "pass/fail" approach. While this vastly simplified the issue of data being highly accurate for all applications it was not able to accommodate opportunities whereby data could be transferred and used for applications requiring lesser accuracy.

Scope of Project

The scope of this standard project involves a determination of various levels of geospatial data accuracy for geospatial entities on or near the seafloor. It is primarily oriented toward a common understanding of geospatial positioning standard for hydrographic (sounding) data. Secondarily, it can be applied to other features that are portrayed on a nautical chart or bathymetric map, or included in a data base -- including aids to navigation and shorelines. A special part to the positioning accuracy standard is need in order to accommodate the unique requirements of hydrographic surveying. The accuracy of this type of surveying is highly dependent upon knowledge of tidal datum planes and the special accuracy requirements to support safe navigation.

Methodology/ Approach

The approach that is being used to develop this standard has been undertaken by the International Hydrographic Organization's S-44 working group. U.S. Membership includes the National Oceanic and Atmospheric Administration, the Defense Mapping Agency, and the Naval Oceanographic Office. The FGDC endorced standard will basically be an adaption of the international standard with possible extensions to include highly accurate surveys and other applications within the domestic community that are not applicablable to the international requirement.


It has now been recognized that users of hydrographic data make up a much more diverse group than previously recognized. Hydrographic data are also important for coastal zone management, environmental monitoring, resource developments, legal land jurisdictional issues, ocean and meteorological modelling, engineering and construction planning and many other uses. Even if the standard does not always specifically address these additional users' needs, it is felt that the standard provides them with a basis to assess the quality of hydrographic data.


The principal objective of the standard is to specify minimum standards for hydrographic surveys in order that hydrographic data collected according to these standards is sufficiently accurate and that spatial uncertainty of data is adequately quantified to be safely used by mariners. This will provide a standardized methodology for evaluating survey data and reporting resultant data quality through a standard statistical approach. It is expected that this will permit much wider use and acceptability of data for 2nd and 3rd parties. Analogous to the Underwriters Laboratory.

Participating Agencies/Organizations

Primarily organizations who will be involved in the development of this standard are the U.S. navigation and seafloor science related community. These include the National Oceanic and Atmospheric Administration, the US Geological Survey, the Minerals Management Service, the United States Coast Guard, the U.S. Army Corps of Engineers, the United States Navy Oceanographic Office, and the National Imagery and Mapping Agency. There is also interest in this standard from private surveying contractors, various agencies within state and local governments, and private citizens. We intend to hold at least two open forum/workshop type meetings to explain the standard to the effected community. One meeting will be during the Coastal Zone 1997 meeting in Boston, Mass in July 1997. The other will be at the CADD-GIS and Mapping/surveying conference in St. Louis in August 1997.

Development and Completion Schedule

It is anticipated that this standard will be completed by approximately November 1997. The draft standard will be essentially completed in May 1997 by the International Hydrographic Office. The subsequent process of making this an FGDC standard will primarily be re-formatting the information into the desired FGDC outline. It is expected that this will take approximately 2 weeks. At this time the proposal will be available for public review. The public review period will be approximately 3 months (June, July, and August 1997). It is anticipated that this standard will receive little critical comment during public review and that comments will primarily be of a clarifying nature relating to the implementation of the standard. Therefore, November 1997 is a reasonable date for completion of the standard.

Anticipated User Community

Agencies that conduct surveys of the marine waters, including high seas, coastal and estuarine, inland lakes and rivers. This standard will greatly increase the potential for exchange of data between and among various federal, state, local governmental agencies, academic institutions, and the private sector. For the first time there will be a common understanding of data accuracy requirements based upon a variety of application profiles and accuracies. It will also provide a common framework for independent evaluation and assessment of hydrographic data for a range of applications, and is independent of technology.


Resources needed to complete this standard are available within the NOAA Office of the Coast Survey. The most significant aspect of the development will be undertaken by the International Hydrographic Organization. The review period will require participation by the effected federal and state agencies.

Relationship to other standards -- This standard will be a section of a multi-part FGDC standard for positioning accuracy for various types of geospatial data. There may also be other less formal procedures, or organizational/agency standards that will be recognized and incorporated (either by reference or replacement) into this standard as appropriate. These are primarily from the Department of Defense MILSTD or U.S. Army Corps of Engineers Surveying Orders, Op Orders, sailing instructions, or project orders..

Completion Date

Approximately November 1997

Target Authorization Body

The Federal Geographic Data Committee will be the authorization body for this standard within the U.S. Internationally it is being authorized by the International Hydrographic Organization

Maintenance Agency

Department of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, Office of the Coast Survey -- Under the leadership of the FGDC Bathymetric and Nautical Chart Subcommittee. Contact is Millington Lockwood, Executive Secretary 1315 EastWest Highway Silver Spring, MD 20910 Phone 301-713-2777x171, FAX 301-713-4019, email