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Effects of water-energy-vegetation feedback on thawing of peat-covered, discontinuous permafrost

Masaki Hayashi, Department of Geoscience, University of Calgary, Canada. Currently a visiting researcher at: Swiss Federal Institute of Aquatic Science and Technology (EAWAG)

Monday 13 June 2011, 1300-1400
LEC Training Room 1

Centre for Sustainable Water Management Seminar

The Hay River Lowland in the Northwest Territories of Canada is a 140,000 square kilometre region of discontinuous and sporadic permafrost with a high density of peatlands. As the region undergoes a rapid warming, large-scale (e.g. 50 km grids), vertical energy transfer models suggest a pole-ward shift of the discontinuous permafrost zone in the future. At a smaller scale relevant to management and adaptation strategies, however, lateral energy transfer mediated by groundwater and soil water is expected to play a major role. Lateral transfer processes are particularly important at the edges of permafrost, marked by forest on the permafrost side and wetland on the non-permafrost side. At the Scotty Creek research basin in the Hay River Lowland, recent observations indicate a rapid lateral thawing of permafrost and deepening of the active layer. Detailed hydrological and soil physical monitoring showed that the deepening of active layer is controlled by the water-energy feedback processes, whereby a small amount of differential deepening of the active layer causes wetter condition in localized areas, which enhances soil heat transfer during thawing seasons and further deepens the active layer. Geophysical data obtained with the electrical resistivity imaging technique have shown that localized deepening of active layer may eventually lead to complete thawing of permafrost and generation of isolated wetlands. Effects of these processes on watershed-scale hydrology are largely unknown. However, in order to find process-based explanations for recently observed shifts in arctic river-flow regime, it is important to link field-based observations to large-scale models of permafrost energetics and hydrological fluxes.

For Masaki's biography and research interests, please visit his University of Calgary webpage.