ABSTRACT: Process variability and the challenge of streamflow prediction in discontinuous permafrost catchments.

CGRG Bibliography of Canadian Geomorphology
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Abstract

Discontinuous permafrost regions occupy a large portion of northern North America and are considered particularly sensitive to widespread ground-ice melt from a warming climate. Unfortunately, the hydrology of this zone is incompletely characterized due to its remoteness and large geographic area. Research in the subarctic Yukon over the past decade has illustrated that the hydrology of topographically complex discontinuous permafrost catchments is characterized by significant small-scale heterogeneity. Variability in slope aspect gives rise to large differences in available energy that control the disposition of permafrost. Where present, permafrost restricts drainage and enhances near-surface saturation and the development of a surface organic layer up to 0.5 m thick, which plays a key role in controlling runoff rates. Hydrometric and isotopic studies show that slopes underlain by permafrost control the lateral redistribution of water and catchment runoff. In contrast, slopes with seasonal frost have a predominantly vertical water balance, with infiltration and percolation balanced by summer evaporative losses. Although there have been conceptual models of streamflow generation proposed, the large variability in processes at the sub-grid scale has prevented the development of a physically reasonable numerical runoff model of these catchments. Small-scale process variability represents a unique challenge in a cold-regions regions modeling context, and issues of how best to incorporate this variability at different scales must be resolved.

Bibliography of Canadian Geomorphology