How do we measure?
Ever wondered how tall Mount Everest is? What about how wide the Grand Canyon is? Or…. maybe how deep is our deepest ocean?
All of the above questions at one time or another were solved with surveying systems. Yes, the methods have changed over the years, but the profession of surveying remains at the forefront of the exploration revolution.
The methods used to measure Mt Everest’s height have changed over time as technology has advanced. This has also created a variance in the estimates that have been recorded - and not to forget, the height can very well change over time. In the 19th century, the height of Everest was calculated from measurements of the angles between the mountain’s peak and points along the base that was average to the height of the sea. The latest methods use GPS technology, seeing surveyors place numerous receivers, which then calculate the height of the sea from satellites and measurements of gravity at the base.
What about the Grand Canyon? Initially, the Grand Canyon was surveyed by sight in the 1540s by the Spanish Conquistadors on a quest to find the Seven Cities of Gold. Reports are, they greatly misjudged the proportions of the Canyon from the rim to the bottom, only to realise the topography when they climbed down in search of water. It was only in 1857 that the next survey was done! Nowadays the National Parks Service agrees that the widest point is 18 miles or 28.9 km from rim to rim and is updated yearly by surveyors employed by the National Parks Service.
Oceanography surveying is a little different to those above water. Using a variety of instruments operated from coastal and ocean-going vessels ie. boats allow Ocean Surveyors to get the “lay of the land” under the sea. Echo sounders or sonars are used to determine water depth and seabed topography or bathymetry, they also use a range of GPS and multibeam lasers.
All of the questions above about how wide, how tall, how deep are part of our awesome profession. We are just lucky we don't need to traverse the highest mountains, the deepest ditches and the widest valleys to do our job….. But let's be honest…. We at Hanlons probably would do that anyway, we like an adventure.
Surveying…. It's not just a job.