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TitleTiming, duration and magnitude of peak annual water-levels during ice breakup in the Mackenzie Delta and the role of river discharge
AuthorLesack, L F W; Marsh, P; Hicks, F E; Forbes, D L
SourceWater Resources Research vol. 49, issue 12, 2013 p. 8234-8249, https://doi.org/10.1002/2012WR013198
Year2013
Alt SeriesEarth Sciences Sector, Contribution Series 20130014
PublisherAmerican Geophysical Union
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories
NTS106M; 106N; 107B; 107C
AreaMackenzie Delta; Mackenzie River
Lat/Long WENS-136.0000 -132.0000 70.0000 67.0000
Subjectshydrogeology; water levels; ice; rivers; discharge rates; deltas
Illustrationslocation maps; hydrographs; plots; tables; tables
ProgramCoastal Infrastructure, Climate Change Geoscience
AbstractNorth-flowing pan-Arctic rivers have important effects on the Arctic Ocean, but their river-ocean interfaces, including some with vast deltas such as the Mackenzie, have complex hydrology and remain poorly understood. Analysis of 38 years (1973-2010) of water levels and river discharge at the head of the Mackenzie Delta, 47 years (1964-2010) of water levels in the mid-delta, and 27 years (1984-2010) of water levels in the outer delta permitted evaluation of changes in the timing, duration, and magnitude of peak annual water levels during river-ice breakup. The initiation date of freshet-discharge into the delta has not changed, but the duration from freshet initiation until peak water levels in the central delta (i.e. duration of ice clearance) has shortened from 35 to 27 days since 1964. The height of annual water-level peaks in the outer delta at Reindeer Channel has declined by 0.4 m from 1984 to 2010, but complicating factors may be influencing this result. Winter-discharge has increased by 25% from 1973 to 2009, but this amount is too small to cause a trend in total Mackenzie discharge. Breakup-discharge (i.e. occurring during ice clearance through the central delta) has not significantly changed. The lag time from freshet discharge initiation into the delta until initial breakage of the river ice-sheet has declined by 6.6 days from 1974 to 2007, and is sufficient to account for the shortened period of river-ice clearance. Declining snow pack depths during April suggest that river-ice is melting more rapidly because of declining insulating effects over the ice surface.
Summary(Plain Language Summary, not published)
North-flowing Arctic rivers have important effects on the Arctic Ocean, but their river-ocean interfaces, including some with vast deltas such as the Mackenzie, have complex hydrology and remain poorly understood. Analysis of 38 years (1973-2010) of water levels and discharge at the head of the Mackenzie Delta, 47 years (1964-2010) of water levels in the mid-delta, and 27 years (1984-2010) of water levels in the outer delta permitted evaluation of changes in the timing, duration, and magnitude of peak annual water levels during breakup. The initiation date of freshet discharge into the delta at Tsiigehtchic has not changed, but the duration from initiation to peak water levels in the central delta at Inuvik has shortened from 35 to 27 days since 1964. Winter-discharge has increased by 25% from 1973 to 2009, but this amount is too small to cause a trend in total Mackenzie discharge. Breakup discharge has not significantly changed.
GEOSCAN ID292518