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Southeast Texas Orthometric Heights

Suppression of Orthometric Heights on NGS Datasheets in Southeast Texas

In March 2021, the National Geodetic Survey (NGS) suppressed the NAVD 88 heights on the datasheets for the vertical control network in southeast Texas, a region that extends south and west from the Texas-Louisiana border and includes Beaumont, Houston, Galveston, and Rosenberg. NGS will continue to offer multiple opportunities to meet with stakeholders and discuss collaborative opportunities to collect, process, and submit updated height information for the region. Together, we can prepare for the transition to the modernized National Spatial Reference System, which will greatly benefit dynamic areas like the Gulf Coast by better accounting for the reality that positions and heights change over time.

Call to Action — GPS Campaigns to Re-Densify the Network and Prepare for NAPGD2022

An improved vertical control network will be needed to provide enhancements for rebuilding and improving infrastructure in the area. Collecting more recent data will also help with flood plain management, flood hazard identification and risk assessment, and elevation certificates.

NGS encourages local partners to perform campaign-style GPS surveys on survey marks of interest and submit the data to NGS through OPUS Projects.

  • Marks for which GPS data is submitted to NGS before December 31, 2021, will have 2020.0 Reference Epoch Coordinates automatically computed and released as part of the modernized NSRS.
  • GPS data on marks with published NAVD 88 heights will be used to create the transformation grids between NAVD 88 and NAPGD2022.

NGS to Provide Technical and Logistical Support and Training

NGS has an array of outreach and educational materials, online data and tools, and online and virtual training available to support those who would like to contribute data.

  • NGS will help with the coordination and planning needed for densification projects for ensuring the availability of control with accurate heights by conducting new leveling and GPS projects.
  • NGS will provide OPUS Projects training workshops that will show surveyors how to transfer heights from the few marks with valid heights to bench marks close to their worksite.
  • NGS will participate in collaborative workshops organized by local partners to plan on how surveyors can densify the vertical control in the region using OPUS Projects.

Link to Map: SE TX Valid Ortho. Heights