You may not have noticed, but depending where you are in Canada, heights may have changed by a few dozen centimetres.
Natural Resources Canada has released a new reference standard for measuring height based on the gravitational forces that affect sea levels. The Canadian Geodetic Vertical Datum of 2013 brings the country in line with much of the rest of the world and will improve accuracy in everything from GPS or GIS mapping to water management
Height measurement among human structures is often conducted from the base to the peak of a structure or landmark feature. The Burj Khalifa building in Dubai rises to about 830 metres from its base. But mountain heights are often calculated by height from sea level. For example, Mount Everest reaches around 8,850 metres.
The sea isn’t as level as you think, though — gravity affects it differently based on things such as the density of earth beneath the water and the presence of nearby land. The science of geodesy takes all this into account and works a reference standard for what the sea level would be in a given area based on gravitational pull.
Denis Hains, director of the Canadian Geodetic Survey, says the new system will facilitate access, reduce survey costs and allow for the use of new technologies. It will help in the mapping of remote areas and indicate which way liquid flows at a given point. Through updated GPS systems, it will help hikers moving through different elevations as well as assisting mining companies to map what’s under the earth.
“The implementation of the CGVD2013 is a very big achievement for surveying, mapping and Earth Observation in Canada,” he says.
This standard will be the first update to the height reference since 1928.