November 5, 2015
Balfour Glacier, New Zealand Retreat 1990-2015
Posted by Mauri Pelto
Balfour Glacier drains west from Mount Tasman in the Southern Alps of New Zealand. The ablation is a low slope, 8 km long debris covered tongue extending from the terminus near 800 m to 1600 m. The glacier is fed by avalanching off of Mount Tasman to the west, the southern flank of the Fox Range to the north and the northern flank of the Balfour Range to the south. Gjermundsen et al (2011) examined the change in glacier area in the central Southern Alps and found a 17% reduction in area mainly from reductions of large valley glaciers such as Balfour Glacier. The volume loss of New Zealand glaciers is reported as 36% from 1978 to 2015, from 54 cubic km to 34 cubic km.
Topographic map of Balfour Glacier area of New Zealand from http://www.topomap.co.nz/ . Blue arrows indicate flow, red arrows at 1990 terminus and yellow arrow at 2015 terminus
In 1990 the glacier ended at 700 m with a snowline at 1600 m. The lower 18 km of the Balfour Glacier is debris covered. Only the upper 8 km has snowcover. In 2015 the terminus has retrated 1250 m, the snowline is at 1800 m, with the lower 20 km debris covered. The terminus reach has continued to appear stagnant from 1990 to 2015. Balfour Glacier has not developed a significant proglacial lake at its terminus, which has limited the retreat compared to Tasman Glacier or Mueller Glacier. Google Earth indicates the retreat of stagnant debris. The main glacier meltwater outlfow issues from the glacier at the yellow arrow in 2012, 600 m above the terminus.
Landsat Analysis of 1990 above and 2015 Below of Balfour Glacier. Red arrow is at 1990 terminus and yellow arrow at 2015 terminus. The purple arrows indicate area of thinning upglacier.
2006 Google Earth image of Balfour Glacier above and 2012 image below. The red arrow is at the terminus location in 2006, the yellow arrow is at the 2012 location where the glacier stream issues from beneath the glacier. The purple arrows