| Subdivision Type1: | Country |
| Subdivision Name1: | Iceland |
| Length: | 115km (71miles) |
| Discharge1 Avg: | 122m3/s[1] |
| Mouth: | Atlantic Ocean |
| Mouth Coordinates: | (primary) |
| Basin Landmarks: | Kirkjubæjarklaustur |
| Tributaries Left: | Grjótá, Hellisá, Fjaðrá |
| Tributaries Right: | Útfall, Nyðri-Ófærá, Syðri-Ófærá |
The Skaftá (pronounced as /is/) is a river in South Iceland. It is primarily glacial in origin and has had its course modified by volcanic activity; as a result of both, it often floods because of glacial melting.
The river's primary source is two subglacial "cauldrons" beneath Skaftájökull, part of the Vatnajökull glacier in the interior of Iceland.[2] [3] It also receives spring-fed water from Langisjór, a lake a short distance to the west from which a tributary called the Útfall runs into the Skaftá. Other tributaries include the North and South Ófaerá, the Grjótá, and the Hellisá.[4] [5]
West of Skaftárdalur, a farm named for the river valley, the Skaftá runs over a lava field in many channels, which recombine into three for the remainder of its course to the Atlantic: the Eldvatn or Ása-Eldvatn combines with the River Kúðafljót; the Ásakvísl or Árkvísla flows under a sand-covered lava field and has been affected by road construction; the third, easternmost branch, which flows near Kirkjubæjarklaustur, retains the name Skaftá[5] but has extremely low water levels when temperatures are lowest.[4] Its total length is approximately 115km (71miles).[5]
The river was bridged at Kirkjubæjarklaustur in 1903 and the Ása-Eldvatn was bridged soon after. Efforts to bank and bridge the Ásakvísl have led to undermining of the bridge works and to erosion of land formerly watered by it.[5]
Beginning on June 8, 1783, the multi-year eruption of the volcanic system including Grímsvötn and Þórðarhyrna (sometimes referred to in Icelandic as the Skaftáreldur, Skaftá Fires)[6] filled the river valley with lava, including a gorge thought to have been 200m (700feet) deep,[7] diverting its flow into the multiple shallow channels that now characterize its course. As a result it is subject to jökulhlaups (glacial outburst floods), which occur every one to two years.[2] [3] [4] [5] [8] [9] The 2015 flood was unusually damaging,[8] the largest since records began.[10]