A Comparison of two Recent Jökulhlaups from An Ice-dammed Lake, Søndre Strømfjord, West Greenland

The hydrographs of two jökulhlaups resulting from the sudden drainage of an ice-dammed lake in West Greenland in 1984 and 1987 are compared. The first flood had a similar peak discharge to the second but drained only two-thirds of the total volume of the 1987 event which amounted to 32–36 × 106 m3 in 36 h. Calculations based on the lake refill time suggest that it drains every 2–3 years, but that peak flows may be variable from flood to flood. The timing of the jökulhlaups in relation to the melt season may reflect variations of water pressure within the subglacial drainage networks, and changes in the configuration of these networks and the positions of crevasses on an annual basis.