Glacial lake drainage near Søndre Strømf jord. West Greenland

ABSTRACTThe controls on rapid surface lake drainage on the Greenland ice sheet (GrIS) remain uncertain, making it challenging to incorporate lake drainage into models of GrIS hydrology, and so to determine the ice-dynamic impact of meltwater reaching the ice-sheet bed. Here, we first use a lake area and volume tracking algorithm to identify rapidly draining lakes within West Greenland during summer 2014. Second, we derive hydrological, morphological, glaciological and surface-mass-balance data for various factors that may influence rapid lake drainage. Third, these factors are used within Exploratory Data Analysis to examine existing hypotheses for rapid lake drainage. This involves testing for statistical differences between the rapidly and non-rapidly draining lake types, as well as examining associations between lake size and the potential controlling factors. This study shows that the two lake types are statistically indistinguishable for almost all factors investigated, except lake area. Thus, we are unable to recommend an empirically supported, deterministic alternative to the fracture area threshold parameter for modelling rapid lake drainage within existing surface-hydrology models of the GrIS. However, if improved remotely sensed datasets (e.g. ice-velocity maps, climate model outputs) were included in future research, it may be possible to detect the causes of rapid drainage.

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Stratigraphic evidence for multiple drainings of glacial Lake Missoula along the Clark Fork River, Montana, USA

Quaternary Research ◽

10.1016/j.yqres.2006.05.009 ◽

2006 ◽

Vol 66 (2) ◽

pp. 311-322 ◽

Cited By ~ 18

Author(s):

Larry N. Smith

Keyword(s):

High Volume ◽

High Energy ◽

Glacial Lake ◽

Last Glacial ◽

Lacustrine Deposits ◽

Clark Fork River ◽

Gravel Bars ◽

Northwest Montana ◽

Lake Drainage ◽

The Last Glacial

AbstractGlacial Lake Missoula, a source of Channeled Scabland flood waters, inundated valleys of northwest Montana to altitudes of ∼ 1265 m and to depths of >600 m, as evidenced by shorelines and silty lacustrine deposits. This study describes previously unrecognized catastrophic lake-drainage deposits that lie stratigraphically beneath the glacial-lake silts. The unconsolidated gravelly flood alluvium contains imbricated boulder-sized clasts, cross-stratified gravel with slip-face heights of 2–> 35 m, and 70- to 100-m-high gravel bars which all indicate a high-energy, high-volume alluvial environment. Gravel bars and high scablands were formed by catastrophic draining of one or possibly more early, high lake stands (1200–1265 m). Most glacial-lake silt, such as the Ninemile section, was deposited stratigraphically above the earlier deposits, represents a lower lake stand(s) (1050–1150 m), and was not deposited in lake(s) responsible for the highest discharge events. The glaciolacustrine silt-covered benches are incised by relict networks of valleys formed during the drainage of the last glacial lake. Significant erosion associated with the last lake draining was confined to the inner Clark Fork River canyon.

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

Journal of Glaciology ◽

10.3189/002214311796405997 ◽

2011 ◽

Vol 57 (202) ◽

pp. 238-246 ◽

Cited By ~ 36

Author(s):

Andrew J. Russell ◽

Jonathan L. Carrivick ◽

Thomas Ingeman-Nielsen ◽

Jacob C. Yde ◽

Meredith Williams

Keyword(s):

Peak Discharge ◽

Accurate Information ◽

Lake Basin ◽

Field Surveys ◽

West Greenland ◽

Northern Margin ◽

Lake Volume ◽

Significant Attenuation ◽

Dammed Lake ◽

Lake Drainage

AbstractJökulhlaups in 2007 and 2008 from an ice-dammed lake at the northern margin of Russell Glacier, West Greenland, marked the onset of a renewed jökulhlaup cycle after 20 years of stability. We present a record of successive ice-dammed lake drainage events and associated ice-margin dynamics spanning ∼25 years. Robust calculations of lake volumes and peak discharges are made, based on intensive field surveys and utilizing high-spatial-resolution orthophotographs of the lake basin and ice margin. These data enable identification of controls on the behaviour of the ice-dammed lake and provide the first field-based examination of controls on jökulhlaup magnitude and frequency for this system. We find that Russell Glacier jökulhlaups have a much higher peak discharge than predicted by the Clague–Mathews relationship, which we attribute to an unusually short englacial/subglacial routeway and the presence of a thin ice dam that permits incomplete sealing of jökulhlaup conduits between lake drainage events. Additionally, we demonstrate that the passage of jökulhlaups through an interlinked system of proglacial bedrock basins produces significant attenuation of peak discharge downstream. We highlight that improved understanding of jökulhlaup dynamics requires accurate information about ice-dammed lake volume and ice-proximal jökulhlaup discharge.

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