November 3, 2017

Gråfjellsbrea, Norway Retreat Forms New Lake

Posted by Mauri Pelto

Gråfjellsbrea Retreat in Landsat images from 1999 to 2017.  Red arrow indicates 1999 terminus, yellow arrow the 2017 terminus location. 

Gråfjellsbrea is an outlet glacier on the northwest side of the Folgefonna  Icefield that drains into Mysevatnet.  The 2012 Norwegian Glacier Inventory notes the glacier having an area of 8.77 square kilometers in 2002.  In 2016 the Norwegian Water Resources and Energy Directorate (NVE) reported this glacier to have the greatest retreat in 2016 of the 36 glaciers where they measure terminus fluctuations annually.  The NVE report indicates a 550 m retreat from 2002-2016.  Here we examine Landsat imagery  from 1999-2017 that indicates the formation of three new lakes at the terminus of the glacier.

In 1999 the glacier terminated in a bedrock valley east of Grafjellsvatnet.  By 2002 minor retreat had led to formation of a proglacial lake.  The snowline was quite high that year with only a few pockets of retained accumulation.  By 2016 the glacier had receded 550 m since 2002 exposing a narrow length of similar length.  The terminus did retreat significantly~100 m in 2017, the exact distance will be reported by NVE in the coming months.  

Mysevatnet is a reservoir impounded for hydropower production. The lake through a tunnel falling 825 m to produce 250 MW at the Statkraft operated Mauranger Plant  NVE (2014) reports there have been no Jokulhlaups from Grafjellsbrea.This glacier is one of many in Norway supplied by glacier runoff, where the glacier is retreating, Storglombreen is another example.

Digital Globe image of Grafjellsbrea and adjacent lakes.

Grafjellsbrea in 2006 with the lake much smaller, NVE image in the Norwegian Glacier Inventory