Runoff generation in thawing discontinuous permafrost terrains

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The southern Taiga Plains ecoregion is one of the most rapidly warming regions on Earth, and is experiencing unprecedented rates of industrial expansion and related human disturbance. The permafrost in this region is relatively warm, thin and discontinuous. As a result, permafrost thaw is widespread and often leads to the transformation of forested permafrost terrains to permafrost-free, tree-less wetlands. Such permafrost thaw-induced landcover change has the potential to disrupt the hydrological cycle. However, the hydrological implications of this permafrost-thaw induced land cover transformation remain poorly understood despite its demonstrated pan-arctic occurrence. As a result, there is an urgent need for an improved understanding of, and ability to predict permafrost thaw and its hydrological consequences. My research programme will develop and mobilise new knowledge on permafrost thaw-induced land-cover change and the resulting hydrological impact; and use this new knowledge to develop a new suite of predictive hydrological modelling tools. Field measurements will concentrate on three observatories located along a ~300 km south-to-north transect extending over the peatland-dominated southern fringe of discontinuous permafrost. This transect is ideally suited for the study of permafrost thaw-induced changes to ecosystems and the resulting impacts on surface hydrology, since it covers a wide range of permafrost ecosystem characteristics along a climate gradient. The following specific objectives will be met at each node: 1) Map the changing spatial distribution of permafrost, wetland and forest coverage over the past 60 years; 2) For different ground thaw and moisture conditions, conduct field studies to improve the understanding of the volume and timing of runoff; 3) Simulate the major water flux and storage processes controlling runoff; 4) Improve the ability to characterize permafrost impacts at larger scales through field investigation and subsequent adaptation of a regional-scale permafrost model; and 5) Estimate future quantities of runoff and surface water storage under possible scenarios of climate warming and human disturbance. Improved knowledge and predictive capacity of permafrost thaw patterns, rates, impacts and feedbacks will improve water planning, management and security by reducing the uncertainty on the future availability of freshwater, and enable better mitigation strategies to offset negative impacts.