23.12.2019 | Logbook
SLF researcher Yves Bühler has now been in New Zealand for five months and his research trip is drawing to a close. But before he heads for home, he seizes the opportunity to help measure the Brewster Glacier, which is melting more and more despite the massive snowfall.
During the spring holidays, which take place in October in New Zealand, we travelled across the southern part of the country's South Island in a camper van. Although a visit to the Milford Road patrol team had prepared me for the potentially extreme scale of avalanches that can occur here, we overcame our reservations about the serious risks involved and decided to visit Milford Sound, where we sailed through the unique landscape of this fjord-like bay in perfect weather.
It was there that we also encountered our first sandflies! The bites of these minute black insects are extremely painful, and if you scratch them they itch for days.
We then pushed on, driving further into the extremely dry landscape of Central Otago. Although only 100 km as the crow flies from the wet, west coast, which enjoys up to 7,000 mm of rainfall a year, this part of New Zealand receives a paltry 300 mm. This stark contrast illustrates the tremendous variety of landscapes on New Zealand's South Island.
Measuring snow depth on the glacier
At the beginning of November, my series of field trips was crowned with an excursion onto the Brewster Glacier, about 230 km northwest of Dunedin. Being relatively easy to access, this glacier is one of the most intensively researched in New Zealand. By Kiwi standards, this means it is roughly just a 20-minute helicopter flight away from the nearest base. This glacier is measured twice a year at specified points to determine its melt rates. Scientists originally assumed that it was still growing, due to the huge winter snowfall, but sadly photogrammetric studies by my research partner Pascal Sirguey show that this glacier, too, is melting away, losing about 2.7 million tons of ice a year, and will soon be history.
So we stow our ski equipment and other material on board the helicopter and fly over towering rainforests to the glacier's accumulation area, around 2,000 m above sea level. Together with a female colleague, with the help of a GPS, my job is to cover more than 80 points systematically spread across the entire glacier, measuring the snow depth at each one. But the kind of avalanche probe we use for this purpose in Davos definitely wouldn't be much use, being way too short! On average, the snow here on the glacier is more than 4.5 m deep, so we have to use extendable steel pipes that can be screwed together. And they aren't exactly light! The maximum snow depth we recorded was 7.5 m. At 8 p.m., after an intense day's work, we dragged ourselves back to camp and the 'comfort' of our tents. Only then were we told that hardly anyone had managed to measure all the points in a single day before. So that was something to be proud of. That said, I feel obliged to point out that far more extensive data could have been gathered more efficiently using a drone.
The pasta we had for dinner went down a treat! Even after a cold, windy night in our tents, by the morning the energy had flowed back into our tired legs, so we set off on a short ski tour and were amply rewarded by the view from the summit over the deserted landscape and massive, pristine forests. At noon the helicopter flew us back down into the valley.
My research trip is already at an end. Over five eventful months, I learned a tremendous amount about surveying and photogrammetry. From the word go, I got on really well with my colleagues at the university here, and became firm friends thanks to our demanding, intensive field work. And we will continue working together, too. Indeed, work is now beginning on a dissertation focused on avalanche simulations in New Zealand, which I and my research partner Pascal Sirguey will supervise. Also included is a research visit to the WSL Institute for Snow and Avalanche Research (SLF).
My family has had a great time here in New Zealand and, given the choice, would probably prefer not to go home! But return to Davos we must, in mid-January, in the heart of winter. Before we go back, though, we intend to explore northern New Zealand. Who knows, maybe we'll still be lucky enough to spot the orcas we've been longing to see. In any case, we've already booked a whale watching tour.