Sonar mapping Lake Wakatipu

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Niwa researchers Arne Pallentin, left, and Pete Notman are mapping Lake Wakatipu to study the potential risk of landslips and tsunamis in Queenstown during an earthquake

Researchers are using state-of-the-art sonar to produce a detailed map of the lakebed of Lake Wakatipu. Miranda Cook catches up with them onboard the Rukuwai II.

Explorers have been mapping Queenstown’s mountain ranges and forests centuries, yet landscapes hidden in the dark depths of the mighty Lake Wakatipu remain something of a mystery.

On a two-week expedition to map the “lake that breathes”, a marine biologist nicknamed “pirate Pete” and a German-born geologist are hunting for natural, underwater treasures – plunging valleys and steep mountain ranges.

On board the Rukuwai II, the National Institute of Water and Atmospheric Research (NIWA) researchers, Pete Notman and Arne Pallentin, are using sonar technology to map what the lake’s terrain looks like, which hasn’t been done since the 1970s.

Advances in technology allow the pair to paint a picture of the lake like never before. The sonar equipment operates like a “high-tech fish finder”, using sound to create a 3D map.

“The geographical features of the lakebed are spectacular; we can be 30 metres from shore and be in 200 metre-deep water,” Notman says.

So why is it important for scientists to know what lies beneath?

Project leader Dr Joshu Mountjoy, who will analyse the data, says studying the lakebed shows if landslides or tsunamis have happened in Lake Wakatipu before, and whether they could happen again, particularly during an earthquake.

 

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miranda.cook@scene.co.nz