A new cycle of jökulhlaups at Russell Glacier, Kangerlussuaq, West Greenland

Jokulhlaups in 2007 and 2008 from an ice-dammed lake at the northern margin of RussellGlacier, West Greenland, marked the onset of a renewed jokulhlaup cycle after 20 years of stability. Wepresent a record of successive ice-dammed lake drainage events and associated ice-margin dynamicsspanning 25 years. Robust calculations of lake volumes and peak discharges are made, based onintensive field surveys and utilizing high-spatial-resolution orthophotographs of the lake basin and icemargin. These data enable identification of controls on the behaviour of the ice-dammed lake andprovide the first field-based examination of controls on jokulhlaup magnitude and frequency for thissystem. We find that Russell Glacier jokulhlaups have a much higher peak discharge than predicted bythe Clague–Mathews relationship, which we attribute to an unusually short englacial/subglacialrouteway and the presence of a thin ice dam that permits incomplete sealing of jokulhlaup conduitsbetween lake drainage events. Additionally, we demonstrate that the passage of jokulhlaups through aninterlinked system of proglacial bedrock basins produces significant attenuation of peak dischargedownstream. We highlight that improved understanding of jokulhlaup dynamics requires accurateinformation about ice-dammed lake volume and ice-proximal jokulhlaup discharge.