The relationship of increasing trends in GRACE observed total water storage to landscape changes in the Southern Taiga Plains
Wednesday, 17 December 2014
The southern margin of discontinuous permafrost in Canada is highly sensitive to climate change. Warming to this region causes rapid thaw and disappearance of permafrost resulting in large changes to ecological and hydrological processes. Changes in hydrology result from permafrost thaw induced subsidence and conversion of tree-covered peat plateaus into bogs and channel fens. . Bogs, fens and plateaus have contrasting hydrological functions. The elevated plateaus with their shallow root zone due to frozen soils convert a relatively high proportion of hydrological input to runoff which they convey to adjacent channel fens and bogs. Bogs are largely water storage features and are typically surrounded by raised peat plateaus, while channel fens transmit water to streams and rivers. In the Scotty Creek watershed, within the southern Taiga Plains regions of Canada’s Northwest Territories, numerous researchers have documented the decline of peat plateaus as a proxy for areal loss of permafrost terrain, and concomitant increases of wetland coverage. Analysis of spatial trends in global total water storage as measured by the Gravity Recovery And Climate Experiment (GRACE) satellites suggest a increasing trend of 6+/-1 mm/year water equivalent units over this region during the period 2003-2013. Analysis of a water budget constructed for the Scotty Creek watershed suggest that this long term trend is only weakly associated to the moderate increases to precipitation while the statistically significant increasing trends observed in discharge in this watershed would likely result in opposite sign. Further, seasonal trend analysis of the GRACE total water storage observations suggest that much of the increase in total water mass over this region occurs over the warm season suggesting that larger snowpacks are not driving the mass increase. In this presentation the changes to total water storage are compared to the trends of landscape change over this region to corroborate the rates of total water mass increase with changes in area of storage features.