SSSI Land Surveying Commission News – July 2019

June 30, 2019
Mount Everest – A Shrinking Mountain?

While recent media reports have shown queues of hopefuls waiting to ascend the summit of Mt Everest, a Nepali government survey team conducted a successful summit expedition to Mt Everest on 22 May last as part of a two-year program to determine an accurate height.

Mount Everest is known in Nepali as Sagarmatha and in Tibetan as Chomolungma. Nepal celebrates Sagarmatha Day on 29 May each year to commemorate the ascent of the summit by Sir Edmund Hillary and Tenzing Norgay in 1953.

After the devastating mega earthquake on 25 April 2015, which killed 9,000 people, it was rumored the peak had shrunk. The height of Mount Everest is the subject of interest not only for the expedition, scientists and researchers but also for the whole world.

Methods to measure the height of Mount Everest have changed over time, from simple geometry in the past, to GPS more recently. Estimates of the height of Everest vary but its official height is currently 29,029 feet or 8,848metres. Teams from around the world, including China, Denmark, Italy, India and the United States, have come up with other calculations, which have sometimes strayed a little bit higher, or a little bit lower, than that figure. Italy, in 1992, lopped seven feet off the standard height, measuring it at 29,022 feet. In 1999, a measurement by American scientists pushed the peak a little higher, saying the mountain reached 29,035 feet

Ganesh Prasad Bhatta, Head of Nepali Government’s survey department says:

“Nepal has never measured Everest on its own although the world’s highest peak lies in its territory. So, we want to prove to our people that Nepal is capable of measuring Everest.”

Since 2017, the Nepalese Survey Department has prepared a methodology to measure Mount Everest’s height, which includes a variety of surveying technologies. Nepali surveyors have been precise levelling to carry sea level heights from the southern plains of Nepal to selected control points. Around 250km of precise levelling has been carried out.

Trigonometrical levelling has then been performed from these selected control points and a Gravity survey is being conducted at over 100 gravity stations to define the local geoid. A GNSS-based survey is also being conducted for determining locations of gravity points, benchmarks as well as top of Sagarmatha (Everest). A team of Sherpas were also trained to bring a GPS receiver to the summit. The cost to measure the mountain is estimated at $250,000.

The summit measurement team was led by Chief Survey Officer Mr. Khimlal Gautam with Survey Officers Rabin Karki, Suraj Singh Bhandari, and Yuvaraj Dhital and supported by a team of five Sherpas. The four surveyors and supporting Sherpas spent 1¼ hours on the summit at 3.15 am on 22 May conducting GNSS Observations and a GPR Survey.

It is understood that final results will be available in about two months.

Lindsay Perry
Chair, SSSI Land Surveying Commission
Chair, SSSI Victoria Regional Commission

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