CGRG Bibliography of Canadian Geomorphology
Search Results
Author : Carey, S.K.; and Quinton, W.L.
Date : 2001.
Title : Hillslope runoff processes in the Canadian Arctic and Subarctic: the role of frozen ground and organic soils.
Publication : AGU Chapman Conference on State-of-the-Art Hillslope Hydrology. 8-12 October, 2001. Sunriver, Oregon.
Issue :
Page(s) :
Abstract
In the Canadian Arctic and Subarctic, subsurface drainage is strongly influenced by frozen ground (both seasonal and permanent) and organic soils that mantle the hillslopes. As part of the Canadian GEWEX Program, studies were initiated to examine hillslope runoff processes in an arctic catchment with continuous permafrost and a subarctic catchment with discontinuous permafrost. Subsurface flow was the dominant mechanism conveying water from hillslopes to the stream channels. Lateral flow was confined to hillslopes with porous organic soils overlying less permeable mineral substrates, setting up a two-layer flow system whereby most drainage occurred as rapid matrix flow in the porous organic layer and/or as preferential flow in inter-hummock channels, soil pipes and interconnected surface depressions. On subarctic slopes without permafrost or organic soils cover, runoff was not observed and hydrological fluxes were predominantly vertical. Runoff was greatest during and immediately following snowmelt when the organic layer rapidly wet-up from the frozen organic/mineral interface and followed highly transmissive near-surface pathways to the stream. Following melt, the frost table descended and the water table gradually declined above this impermeable barrier. The response of hillslopes to summer rainstorms was controlled by the position of the water table within the porous organic soils, whose hydraulic conductivity decreased with depth. Contributing source areas declined sharply as the water table passed from the organic soils into less permeable mineral layers, disconnecting hillslopes from the drainage network and strongly influencing the shape of stormflow hydrographs. The moisture holding properties of the organic layer significantly influenced the ability of water to be redistributed within arctic and subarctic landscapes. Ongoing research involves the use of isotopic and geochemical indicators for hydrograph separations, catchment residence times, hydrogeochemical flushing (C, N) and the development of coupled heat and moisture models to describe the flow of water through hillslopes with permafrost. Preliminary results of this research will be presented.
Bibliography of Canadian Geomorphology