Hydrology of a Drainage Basin in the Canadian High Arctic

Hydrologic research in the permafrost region has focused mainly upon individual processes. This study integrates the various processes acting on a High Arctic drainage basin, emphasizing the roles played by the energy balance, the uneven snow cover, and permafrost at shallow depths. Long polar winters cause substantial energy losses from the snowpack and the ground. Snowmelt begins in late May or June, and the melt within a basin is complicated by the uneven thickness of the pack. When the shallower snow disappears, the frozen ground in the snow-free areas begins to thaw and to lose water through evaporation, while the residual snow patches continue to release meltwater to the basin slopes. The mode of slope runoff is strongly controlled by the thawing of the active layer. When the thaw depth is shallow and the water supply large, much of the runoff appears as surface flow. As thaw depth increases, subsurface flow prevails. When this water reaches the valleys, it encounters massive snowpacks that retard downstream flow. Over three-quarters of annual discharge is released during the melt period, but occasional high-flow events are also produced by summer rainstorms. About 80 percent of annual precipitation occurs as snowfall, and about 70 percent of total precipitation leaves the basin as runoff. Snow plays a dominant role in Arctic hydrology, with surface energy providing the driving force to generate snowmelt, evaporation, and the annual thawing of the active layer.