The Glacial Hydrology of an Ice-dammed Lake, Ellesmere Island, N.W.T.

Abstract

<p>McMaster Lake is a 7.2 km² ice-dammed lake ponded against the margin of the Ellesmere Ice Cap, Ellesmere Island; Northwest Territories. The lake occupies a deep structural basin, and was found to be smictic, with a near isothermal temperature profile of 0.0-0.5ºC, and a year round 3m thick ice cover. The lake was observed over three seasons to lose 3-5 m of water rapidly during the month of August. In 1974 the outflow was monitored in Siphon Creek and the Sverdrup River, and a characteristic jokulhlaup hydrograph with a peak discharge of 85 m²/sec was observed. Correlation of the temperature, incoming solar radiation, relative humidity, and precipitation data collected at the McMaster Lakes site with Siphon Creek discharge yields a good explanation of variance in discharge prior to the jokulhlaup. The glaciology of the shelving glacier bordering McMaster Lake was found to be instrumental in the lake drainage behaviour, and the origins and activity of the ice shelf are documented. Consideration of the available data on McMaster Lake, and a review of existing theories leads to the proposal of a modified barrier flotation mechanism for the drainage of McMaster Lake.</p>