CHANNEL DEVELOPMENT AND FLUVIAL PROCESSES IN SNOW-FILLED VALLEYS, RESOLUTE BAY, N.W.T.

Abstract

In 1977, this study was carried out in a small drainage basin (33 km2) near Resolute (74°55'N, 94°50'W), Northwest Territories (1) to examine the manner in which meltwater runoff carves channels in the valley snowpack before the channels become stablised on their clastic beds, and (2) to assess the role played by valley snowpacks on fluvial processes. Major factors controlling channel development in the snowpack include the distribution and the characteristics of the snow, which in turn are related to the local topography and the prevailing directions of winter snowdrift. Based on this relationship, an attempt was made to predict the sequences of channel development in terms of several processes including ponding, tunnelling, lateral and vertical shifting, and stream capturing. Availability of water controls the rate of channel development sequences and hence the magnitude of fluvial processes over a flow season. In the case of substantial runoff, the rate of snowpack depletion is rapid. However, since the bulk of annual water discharge occurs while the snow is interposed between the running water and the bed material, little geomorphic work is performed during the early part of the flow season. For four selected sites, calculations suggest a protective effect of the snow in reducing the potential bed material transport.