Coal Lake outlet freeze-up, containment of winter inflows and estimates of telated outburst flood on Wolf Creek, Yukon Territory

TitleCoal Lake outlet freeze-up, containment of winter inflows and estimates of telated outburst flood on Wolf Creek, Yukon Territory
Publication TypeConference Proceedings
Year of Conference1997
AuthorsJasek, M., and Ford G.
Conference Name65th Annual Western Snow Conference
Series TitleProceedings of the 65th Annual Western Snow Conference
Date PublishedMay 1997
PublisherWestern Snow Conference
Conference LocationBanff, Alberta
KeywordsCoal Lake, Spring freshet, Wolf Lake, Yukon River
Abstract

Spring snowmelt is generally the dominant annual peak flow generating mechanism in subarctic regions, thoughsmaller basins may occasionally experience peak flow events due to summer rain storms. An unusual lake outburstflood event was observed at Wolf Creek, a small tributary of the Yukon River. The event was focused at the outletof Coal Lake the only major storage element in the basin.During the unusually cold January of 1996 ice growth at the outlet of Coal Lake created an ice dam which progressively grew through aufies formation as the lake levels increased. The ice dam failed in late April approximately 9 days after the onset of mean daily positive temperatures sending a significant flood wave downstream. This event was in excess of 1996 freshet flows which occurred more than one month later.There are three hydrometric stations on Wolf Creek however these were not activated until the recession of the outburst event. A water balance was carried out to reconstruct this flood event using observed lake levels for the containment period, the recorded recession limbs of hydrographs at the Coal Lake hydrometric station and a downstream hydrometric station, winter recession flows at an upstream hydrometric station and personal observation.The analyses indicated that the outburst event was greater in magnitude than the subsequent freshet event. In addition to facilitating the reconstruction of the annual hydrograph, the analyses provides valuable information on a little known strearnflow generation mechanism in small subarctic basins with lake storage.

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