Updating U.S. & Canadian Water Level Stations to the New International Great Lakes Datum Using GNSS

Session: A Possible New Paradigm to Improve the International Great Lakes Datum and Its Maintenance (2)

Jeff Oyler, NOAA/CO-OPS, [email protected]
Dana Caccamise, NOAA's NGS, [email protected]
MIchael Craymer, NRCan/CGS, [email protected]
Terese Herron, DFO/CHS, [email protected]

Abstract

The International Great Lakes Datum (IGLD) is the height reference used for water levels within the Great Lakes – St. Lawrence River system. This system, one of the world’s greatest fresh water resources, is shared and jointly managed by the U.S. and Canada. Movement of the earth’s crust, due primarily to glacial isostatic adjustment, requires the IGLD to be updated every 25 to 30 years. The next IGLD will be defined by dynamic heights in the new geoid-based North American – Pacific Geopotential Datum of 2022. The implementation of this new IGLD will require the updating of heights at U.S. and Canadian permanent and temporary water level stations. The heights at these stations will be derived from precise GNSS surveys that are coordinated between the U.S. and Canada over a seven year water level observation period from 2017 to 2023. Completion of the IGLD is expected in 2025 and will require the updating of nautical charts for safe navigation, particularly during periods of low lake levels. In addition, low water datum (chart datum) will need to be updated to the new IGLD.  This is critical for the Great Lakes commercial navigation industry, the recreational boating community and ports/harbors across the region.