A glacial outburst flood has begun in Skaftá river in South Iceland, the Icelandic Met Office reports. The water level and flow rate in the river began to increase last night and increased electrical conductivity was also measured. Rangers in Hólaskjól also reported smelling sulphur in the area. The National Police Commissioner and Department of Civil Protection have issued an uncertainty phase due to the event.
The last glacial outburst flood in Skaftá occurred two years ago, in September 2021. Floods in Skaftá are sourced from two ice cauldrons beneath Vatnajökull glacier which usually burst one at a time, but it is possible that this flood is sourced by both the western and eastern cauldrons, according to the Met Office. The 2021 glacial outburst flood was sourced by both cauldrons.
Risk of floods and gas poisoning
There are several hazards associated with such natural events. Firstly, flood conditions are expected in Skaftá river over the next two to three days and some flooding of roads near the river is possible. Secondly, hydrogen sulphide is released from the floodwater as it drains from the Vatnajökull ice cap. The gas is particularly potent at the ice margin, where it can reach poisonous levels of concentration. Travellers are advised to stay away from the edges of Skaftárjökull, Tungnaárjökull, and Síðujökull, where floodwater could burst through the surface. Lastly, travellers on Vatnajökull should stay away from the region, as crevasses will develop rapidly around the ice cauldron.
The cauldrons that source the glacial outburst floods in Skaftá drain every two years on average, producing floods of up to 1,500 cubic metres per second.