in the Vatnajökull ice cap, Iceland

• Main Authors: Bergur Einarsson, Veðurstofu Ísl
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2009
• Subjects: Skaftá; Vatnajökull; glacier; Ice cap; Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.370.9443; http://en.vedur.is/media/vedurstofan/utgafa/skyrslur/2009/VI_2009_006_tt.pdf

Fast-rising jökulhlaups from the geothermal subglacial lakes below the Skaftá cauldrons in Vatnajökull emerge in the Skaftá river approximately every year with 45 jökulhlaups recorded since 1955. The accumulated volume of flood water was used to estimate the average rate of water accumulation in the subglacial lakes during the last decade as 6 Gl (6·106 m3) per month for the lake below the western cauldron and 9 Gl per month for the eastern cauldron. Data on water accumulation and lake water composition in the western cauldron were used to estimate the power of the underlying geothermal area as ∼550 MW. For a jökulhlaup from the Western Skaftá cauldron in September 2006, the lowering of the ice cover overlying the subglacial lake, the discharge in Skaftá and the temperature of the flood water close to the glacier margin were measured. The discharge from the subglacial lake during the jökulhlaup was calculated using a hypsometric curve for the subglacial lake, estimated from the form of the surface cauldron after jökulhlaups. The maximum outflow from the lake during the jökulhlaup is estimated as 123 m3 s−1 while the maximum discharge of jökulhlaup water at the glacier