Snowmelt-induced slushflows, Ellesmere Island, N.W.T., Canada

At Taconite Inlet, northern Ellesmere Island, Canada (82deg 50 min N; 78deg 00 min W), a snowmelt-induced slushflow marked the beginning of streamflow in 1992 from the Lake C2 watershed. Meteorological, snowpack, and hydrological measurements were made during May and June prior to the slushflow, to test a hypothesis that the most likely slushflow initiation site was beneath a large south-facing slope. Four days before the slushflow, the snowpack in flat areas was still sub-freezing (e.g. basal temperatures -9deg to -11deg C), with maximum snow wetness less than 1 percent (by volume). In contrast, the south slope snowpack by this time was warmer and afternoon snow wetness was reaching 2 to 5 percent, due to higher radiative inputs. Following three days of vigorous turbulent heat transfer, a slushflow began in the stream channel below the south slope and traveled 1600 m to the lake. Discharge during the event was the highest observed during three summers (5.5 +/- 2 m³/s), yet was insufficient to breach avalanche debris snow dams. Additional slushflows occurred elsewhere in the watershed during the following week.