Jökulsá á Fjöllum

	Jökulsá á Fjöllum
	Jökulsá á Fjöllum, view of the Hafragilsfoss with the row of craters that stretches across the river
	Data
location	Iceland
River system	Jökulsá á Fjöllum
origin	Brúarjökull Glacier ; 64 ° 39 ′ 53 ″ N , 16 ° 51 ′ 17 ″ W
muzzle	in the Öxarfjörður ( Greenland Sea ) coordinates: 66 ° 8 ′ 50 ″ N , 16 ° 42 ′ 50 ″ W 66 ° 8 ′ 50 ″ N , 16 ° 42 ′ 50 ″ W;
Mouth height	0 m
length	206 km
Catchment area	7380 km²
	Waterfalls: Gljúfrasmiður , Selfoss , Hafragilsfoss , Dettifoss
	Selfoss waterfall of Jökulsá á Fjöllum, above Dettifoss
	Dettifoss from the air
	The river crosses a desert area not far from the Dettifoss
	Mouth of Jökulsá á Fjöllum not far from Ásbyrgi , eastern branch of the Brunná estuary in the middle distance
	Aerial view of Ásbyrgi

The Jökulsá á Fjöllum (Eng. "Glacier river on the mountains", is meant in the highlands) is the second longest river in Iceland with a length of 206 km and has its source on Brúarjökull , one of the valley glaciers of the Vatnajökull ice sheet . It mostly flows through the uninhabited highlands in northeast Iceland and flows into Öxarfjörður not far from Kópasker .

General characteristics

The Jökulsá á Fjöllum has the largest catchment area of all rivers in Iceland with 7,380 km². In 1989, 1,800 km² of this was covered by glacier ice.

Their average water volume at the Dettifoss waterfall is 183 m³ / s. Like all glacial rivers , however, it is subject to strong and rapid changes. On July 30th, 2011 at 6am it was e.g. B. not far from Dettifoss at Grímsstaðir 583 m³ / sec., Which in this case was due to both the increased outside temperature (up to 18 ° C on July 29th) and increased volcanic activity in the east of Vatnajökull under Bárðarbunga and Hamarinn .

Like all glacier rivers, the Jökulsá á Fjöllum also carries large amounts of debris into the estuary area, averaging around 8 million tons per year.

River course

Upper course

The river has its origin between Dyngjujökull and Brúarjökull , two valley glaciers of Vatnajökull. In the cut (isl. Kverk ) between these two glaciers the mountain range of the Kverkfjöll rises . The spring waters of Jökulsá á Fjöllum come first from the Dyngjujökull glacier. Several tributaries also come from the Kverkfjöll and Brúarjökull, of which the Kreppa is the largest. After the two rivers flow 40 km more or less parallel to each other, this flows below the Herðubreið into the Jökulsá á Fjöllum, which until then flowed to the northeast.

Middle course

From then on, the river widens and flows through the Ódáðahraun , a largely desert-like area characterized by eroded lava and ash fields. The river is now more or less oriented to the north and finally follows the mountain range of Hólsfjöll , after which it is named.

Lower course

Over the last 50 km, the river, which has become a stream, pours one after the other over three large waterfalls, the Selfoss , the Dettifoss and the Hafragilsfoss , before finally entering the lowlands through a deep three-part gorge Jökulsárgljúfur that it created itself .

Muzzle area in the Kelduhverfi

From the height of Ásbyrgi , the river flows further north in several arms for about 20 km before finally flowing into the Greenland Sea at Kelduhverfi in the bay of Öxarfjörður .

Geology: volcanic eruptions and glacier runs

The catchment area of this river is located in the middle of the northern arm of the active rift and volcanic zone of Iceland (NVZ) and is therefore particularly rich in geological phenomena. Here you can find palagonite cones and ridges , large lava fields , shield volcanoes , central volcanoes such as Askja , Bárðarbunga and Kverkfjöll , deep gorges and one of the largest ice sheets in Europe in the form of Vatnajökull. The landscape is characterized by significant traces of volcanic eruptions, partly under glaciers and glacier courses of enormous proportions.

During the last 30 km of its course, the Jökulsá á Fjöllum has shaped the landscape in a special way. Here it flows over the Selfoss , Hafragilsfoss and Dettifoss waterfalls and through the Jökulsárgljúfur gorge in the national park of the same name . This gorge was created by glacier runs of Vatnajökull about 7,100, 4,600, 3,000 and 2,000 years ago, which were probably triggered by eruptions of Kverkfjöll and Bárðarbunga . During the last of these glacier runs, up to 500,000 m³ / sec poured out. Water through the river valley, deepening the gorge and creating the bay-like rock formation of Ásbyrgi , which is no longer traversed by the river, which has sought another course.

At the Hafragilsfoss waterfall and in Vesturdalur (a valley in today's Jökulsárgljúfur National Park), around 6,000 years ago, volcanic eruptions from crevices directly under the river, which are part of the Askja volcanic system , formed the landscape in enormous hydromagmatic explosions . Later the Jökulsá á Fjöllum made a bed again through the layers of tephra , lavas and dykes .

and display information about the image

In Vesturdalur, Hljóðaklettar

Jökulsárgljúfur National Park

Sections of the river that are particularly worthy of protection became part of the Jökulsárgljúfur National Park, which is now part of the Vatnajökull National Park .

Web links

Commons : Jökulsá á Fjöllum - collection of images, videos and audio files

Individual evidence

↑ Number based on: Thor Thordarson, Armann Hoskuldsson: Iceland. Classic Geology in Europe 3. Terra, Harpenden 2002, 139

^ HU Schmid: Dictionary Icelandic - German. Buske, Hamburg, 123, 12, 64

↑ ^a ^b ^c Íslandshandbókin. Náttúra, saga og sérkenni. 1. bindi. Edited by T. Einarsson, H. Magnússon. Örn og Örlygur, Reykjavík 1989, 484

↑ ^a ^b http://vmkerfi.vedur.is/vatn/VV_Frame.php?r=22799&load_graph=1&direct=1&station_id=222&station_name=Austurland&page_id=342 ( page no longer available , search in web archives ) Info: The link was automatically defective marked. Please check the link according to the instructions and then remove this notice. Veðurstofa Íslands, June 30, 2011 (Icelandic); Accessed June 30, 2011@1@ 2Template: Toter Link / vmkerfi.vedur.is

↑ cf. Earthquake activity on July 30, 2011 http://en.vedur.is/earthquakes-and-volcanism/earthquakes/ Icelandic Met Office, July 30, 2011 (English); Accessed July 30, 2011

^ Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 22

^ Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 19f.

^ Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 20

↑ cf. Magnús Tumi Guðmundsson (2006), cit. in: Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 25

^ Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 28

↑ Thor Thordarson puts a glacier run from 2,500 years ago as the most powerful. See: Thor Thordarson, Armann Hoskuldsson: Iceland. Classic Geology in Europe 3. Terra, Harpenden 2002, 139

↑ Number based on: Thor Thordarson, Armann Hoskuldsson: Iceland. Classic Geology in Europe 3. Terra, Harpenden 2002, 139

↑ Some geologists even speak of up to 1 million m³ / s, cf. Sigrún Helgadóttir: Jökulsárgljúfur. Dettifoss, Ásbyrgi and allt þar á milli. Opna, Reykjavík, 2009, 28

^ ^A ^b Thor Thordarson, Armann Hoskuldsson: Iceland. Classic Geology in Europe 3. Terra, Harpenden 2002, 139

[1] Number based on: Thor Thordarson, Armann Hoskuldsson: Iceland. Classic Geology in Europe 3. Terra, Harpenden 2002, 139

[2] HU Schmid: Dictionary Icelandic - German. Buske, Hamburg, 123, 12, 64

[Ísl-3] Íslandshandbókin. Náttúra, saga og sérkenni. 1. bindi. Edited by T. Einarsson, H. Magnússon. Örn og Örlygur, Reykjavík 1989, 484