Photo from the 2018 Skaftárhlaup. This aerial image, captured on August 4, illustrates the peak discharge at Sveinstind.
Updated on 29 August, 17:00
Recent hydrological monitoring at Skaftá near Sveinstindur reveals a slight moderation in the flood’s discharge rate. As of 15:00 today, the river’s flow is estimated at 620 m3/s, a modest increase from 600 m3/s recorded earlier this morning.
The image below highlights the gradual rise in discharge further down the river. Typically, flood waters require about 8 to 10 hours to traverse the distance from the gauging station at Sveinstindur to that at Eldvatn near Highway 1.
The accompanying graph compares discharge measurements from Sveinstindur (blue line) against those from Eldvatn (red line).
Historically, Skaftá has experienced glacial floods at relatively predictable intervals over the last half-century. From 1955 to 2018, the eastern cauldron alone produced 28 floods, while the western cauldron, noted for its frequency, contributed 30 floods within the same timeframe. On average, one flood arises from either cauldron annually.
A correlation exists between peak discharge rates and the intervals between floods. For instance, after a five-year hiatus from the eastern cauldron (2010-2015), the most significant flood recorded in Skaftá erupted in October 2015, peaking at approximately 3,000 m3/s. When we juxtapose the current discharge with past events, particularly considering the latest deluge in 2021, it appears that we are witnessing a typical flood event that should not threaten infrastructure or overflow onto Highway 1.
Historical patterns suggest that discharge levels are unlikely to rise dramatically from their current state and should taper off in the coming days. However, there are precedents for subsequent peaks, where a double glacial flood occurs as a follow-up to the initial rush. The most recent occurrence of this nature transpired in September 2021, when the western cauldron flooded first, followed by the eastern cauldron five days later, reaching a peak discharge of around 1,500 m3/s.
The Icelandic Meteorological Office (IMO) is maintaining close surveillance of the situation. Residents are advised to be aware of potential concentrations of geothermal gases near the Skaftá source, where sulfur dioxide may mix with the floodwaters emerging from beneath the glacier. Air quality in Kirkjubæjarklaustur can be monitored through loftgaedi.is.
Previously reported:
Late last night, both discharge levels and conductivity readings at Sveinstindur began their upward trend. Rangers in the area have also noted sulfurous odors, suggesting the onset of a glacial outburst flood—the last of which occurred in September 2021.
The Skaftár cauldrons—eastern and western—are nestled within the western sector of the Vatnajökull Ice-cap. Floods from the eastern cauldron typically exceed those from the western. As scientists assess satellite data, it remains unconfirmed which cauldron is presently active, though both are under consideration, as witnessed in 2021.
Currently, discharge at Sveinstindur was recorded at 600 m3/s around 9 AM, with expectations that peak discharge will reach Þjóðvegur 1 approximately 10 hours after the maximum is achieved at Sveinstindur. The scale of the flooding depends on which cauldron is contributing to the event.
Given the circumstances, local authorities and civil protection agencies have declared a precautionary state.
Observations from Sveinstindur indicate a discharge of approximately 600 m3/s at 9 AM.
Expected Hazards
It is imperative that locals and visitors remain vigilant regarding possible hazards in the area.
- In the coming days, flooding is expected to affect roads in close proximity to Skaftá’s banks.
- High concentrations of hydrogen sulfide (H2S) are predicted near Skaftárjökul’s edge, advising individuals to maintain a safe distance from the river and surrounding glaciers due to respiratory effects.
- Travelers are urged to avoid areas above Skaftárdal and the peripheries of Skaftárjökull, Tungnárjökull, and Síðujökull while flooding is occurring.
- Crevasses may develop rapidly around the cauldrons, thereby necessitating caution for those traversing the Vatnajökull ice-cap.
A Historical Overview of Floods in Skaftá
The Skaftá cauldrons, both eastern and western, are situated in the western part of the Vatnajökull Ice-cap. These cauldrons are formed due to geothermal activity that melts the glacier from beneath, resulting in water accumulation. When the hydrostatic pressure becomes sufficient to lift the ice above and release the stored water, a flood ensues. Generally, floods from the eastern cauldron are more potent than those from the western cauldron.Floods resembling those we recognize today first appeared in 1955, totaling 59 events. On average, floods from each cauldron occur roughly every two years.
For more in-depth information on hazard assessments related to glacier outburst floods in Skaftá, please refer to the comprehensive guide provided (in Icelandic).