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Glacier lake outburst floods (GLOF)

21.12.2009 | 12:15

A jøkulhlaup is a sudden outburst flood from a glacial lake. Such lakes form at the glacier margins, on its surface or underneath it where the water is dammed by the glacier ice or in front of the glacier impounded by a moraine. Once the water finds a way over, underneath or through the dam, large parts of the lake can be emptied within short time (hours to days) resulting in violent floods. Such floods have caused considerable damage in the past.

An established possibility to reduce the risk of a violent outburst flood, is the controlled drainage of the impounded water through artificial spillways or tunnels either to empty the lake or to lower its level below a critical level. This has been done e.g. at Demmevatnet (Hardangerjøkulen) or at Østerdalsisen (Svartisen). However, at some places, such controlling interventions are not practicable or the urge of the situation does not leave the time required for the task. In such cases, a reliable and operational forecast and warning system is desirable. However, the so far incomplete understanding of outburst initiation complicates a prediction.

Gridabase is a database of glacier hazards which has been compiled within the EU-project Glaciorisk. From Norway, both NVE and UiO participated in this project.

Jøkulhlaups in Norway (recent years)

  • Øvre Messingmalmvatnet at Rundvassbreen, Blåmannsisen in Sørfold, Nordland (text in Norwegian)
  • Glacier lake at Harbardsbreen/ Breheimen in Luster, Sogn og Fjordane
  • Koppangsbreen in Lyngen, Troms
  • Flatbrevatnet at Flatbreen, Jostedalsbreen in Sogndal, Sogn og Fjordane
  • Øvre Svartanutvatnet at Søndre Folgefonn in Odda, Hordaland (text in Norwegian)
  • Heiavatnet at Svartisheibreen, Vestre Svartisen in Rana, Nordland
  • Leirskardsvatnet at Austre Okstindbreen in Nordland
  • Brimkjellen at Tunsbergdalsbreen, Jostedalsbreen in Luster, Sogn og Fjordane
  • Strupvatnet at Strupbreen/ Lyngenhalvøya in Lyngen, Troms

 

Former events

An overview of events prior to 1950 is given by Olav Liestøl: Glacier dammed lakes in Norway. Norsk geografisk tidsskrift, Bind 15, Oslo, s. 122-149.

  • Sauavatnet at Søndre Folgefonn in Etne, Hordaland
  • Demmevatnet at Hardangerjøkulen in Eidfjord, Hordaland (text in Norwegian)
  • Austerdalsvatnet at Østre Svartisen in Rana, Nordland
  • Øvre Mjølkedalsvatn at Mjølkedalsbreen, Jotunheimen in Lom, Oppland
  • Skadevatnet at Vetlefjordbreen, Jostefonn in Balestrand, Sogn og Fjordane
  • Koldevatnet, Tafjord in Valldal, Møre og Romsdal