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NOAA News Releases 2005
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Provides Critical Update on Lower Mississippi Region Surveys

Officials from NOAA, the National Oceanic and Atmospheric Administration, announced new elevations for the state of Louisiana to improve the accuracy of the state’s survey benchmarks and insuring they will remain accurate for longer periods than in the past. The announcements were made during a presentation at the Coastal Zone ’05 conference, the largest international conference for coastal resource management professionals.

“Using the new technologies available to us such as Global Positioning System and NOAA’s Continuously Operating Reference Stations will allow us to provide accurate elevation reference points in an efficient and timely manner,” said Richard Spinrad, Ph.D., assistant administrator for NOAA’s National Ocean Service. “Planners will be better able to determine road and bridge heights relative to water and ground levels from these data, thus assuring evacuation routes and shipping lanes have appropriate clearance to avoid flooding and obstructions.”

Currently NOAA’s National Geodetic Survey is analyzing the historical leveling data as well as new leveling and GPS surveys. They are feeding the data into updated scientific models in order to provide more accurate elevations on a number of benchmarks in southern Louisiana.

NOAA has enjoyed the support and cooperation of a number of institutions and organizations in the Gulf Coast region, especially the Harris/Galveston Coastal Subsidence District, in coordinating efforts to detect and measure subsidence. Many of the specifications and procedures used, and projected for use in the Louisiana Coastal region, were developed in conjunction with the HGCSD.

The Louisiana Spatial Reference Center was established in 2002 at Louisiana State University in response to users’ and public safety needs. The LSRC operates in conjunction with NOAA to develop and provide height modernization procedures in Louisiana as well as to share technology development with others. Congress has specifically provided height modernization funding in fiscal year 2005 for the Gulf Coast states of Alabama, Mississippi, Louisiana and Texas.

“These new heights are considerably more accurate than what we have been able to measure previously,” said Charlie Challstrom, director of NOAA’s National Geodetic Survey. “There is much work to be done - including providing tools, and educating users on how to utilize the new information for future projects.”

NOAA officials noted it is critical that users of the elevation data apply it in accordance with new approaches being developed, and work with the Louisiana Spatial Reference Center to improve the geospatial reference system in Louisiana. While there will be fewer specific benchmarks maintained, the overall accuracy of the heights will be maintained for longer periods.

NOAA officials emphasized that NOAA does not predict the rates of subsidence nor attempt to determine its causes in Louisiana or elsewhere. NOAA is the supplier of data that are then used by the U.S. Geological Survey, U.S. Army Corps of Engineers, state agencies, academics, emergency planners, engineers, surveyors, environmental restoration efforts, and others to determine those rates based on various models.

NOAA released “Technical Report 50” this spring, a compilation of rates of subsidence between 1920 and 1995. The vertical rates in the report, according to the National Geodetic Survey, may not reflect current or future rates of subsidence.

Recently completed GPS surveys through December, 2004 are being added to NOAA’s database and will validate a framework of benchmarks that can be confirmed for use in accurate surveys.

The National Oceanic and Atmospheric Administration, an agency of the U.S. Department of Commerce, is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of our nation’s coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with our federal partners and nearly 60 countries to develop a global Earth observation network that is as integrated as the planet it observes, predicts and protects.

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