Vertical datums typically represent a terrestrial or earth-based surface to which geospatial coordinates (such as elevations or depths) are referenced. The vertical datum is the base foundation for nearly all civil and military design, engineering, and construction projects in the Corps—especially those civil projects that interface with water. Elevations or depths may be referred to local or regional reference datums. These reference datums may deviate spatially over a region, due to a variety of reasons. They may also have temporal deviations due to land subsidence or uplift, sea level changes, crustal/plate motion, or periodic readjustments to their origin or to defined points on the reference surface.
NGVD29 to NAVD88 Fact Sheet
Implement a nationwide datum and subsidence standard methodology for the Corps, initiate and populate database, provide and update guidance manuals containing references to elevations and datums, develop certification process and provide training to reach certification, and develop standard methodology for updating geodetic and water level information within projects.
New and revised guidance documentation involving elevations and vertical datums; standardized process for maintaining vertical control on all flood control, hurricane protection, shore protection, and navigation projects; new and revised training and certification process; nationwide database of projects vertical control.
All USACE engineers, planners, project managers, surveyors and others involved in flood control, hurricane protection, shore protection, and navigation projects
Project vertical control that is tied to consistent National Spatial Reference System provides for consistency of elevations with Federal Agencies including FEMA and USGS map modernization efforts. Maintenance of vertical control in high subsidence areas (e.g. New Orleans, Sacramento) where elevations collected can appear to be higher than actual. Provide consistency of collected data along levees and between levee systems. Ensure accurate relationship to tidal datums and account for changes in tidal epochs due to sea level rise.
Participating USACE Elements
Headquarters, The Army Geospatial Center, Jacksonville, and Sacramento Districts, all Corps District Datum Coordinators, ERDC Coastal and Hydraulics Laboratory
Participating External Partners
NOAA National Geodetic Survey, Center for Operational Oceanographic Products and Services (CO-OPS) and Office of Coast Survey (OCS)