CGRG Bibliography of Canadian Geomorphology
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Author : Carey, S.; and Woo, M.-k.
Date : 2001.
Title : Hillslope runoff and contributing source areas in a subarctic catchment.
Publication : Annual Scientific Meeting of the Canadian Geophysical Union. May 14-17, 2001, University of Ottawa, Ottawa.
Issue :
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Abstract
Hillslope runoff was studied in a subarctic, subalpine environment to improve understanding of runoff generation processes and the variability of hillslope source areas that supply water to the drainage network. Runoff characteristics of four slopes were examined between 1997 and 1999, each with distinct soils, frost, topography and vegetation. Lateral flows were confined to hillslopes with porous organic soils overlying less permeable mineral substrates, setting up a two layer flow system whereby most drainage occurs as quickflow in the porous organic layer and/or as preferential flow in pipes, rills and interconnected surface depression. Components of the snowmelt and stormflow hydrographs were examined to elucidate how the slopes drain following precipitation inputs. Hydrographs responded rapidly to rainfall and displayed extended recessions compared with temperate regions. Recession limbs exhibited up to two components: 1) an initial rapid decline in flows following the hydrograph peak, and 2) an extended recession component often lasting up to several days following the hydrograph peak. A simple kinematic expression was applied to the recessions to infer the contributing areas of hillslopes from the hydrograph shape. Two source areas were identified: 1) a lower slope zone that provided for the initial recession response, and 2) zones further upslope that delivered water through the saturated organic layer to the hillslope base over an extended recession period. The connection of the second source area to the hillslope base was contingent upon the water table being at near-surface positions over much of the hillslope, encouraging enhanced drainage. The results of modelled contributing area compare well with field observations, indicating that the concept of moisture-controlled variable source areas for runoff generation applies to subarctic, subalpine catchments.
Bibliography of Canadian Geomorphology