Application of the snowmelt runoff model to projecting climate change impacts on flow in the Upper Athabasca River Basin




Siemens, Kyle Alexander

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The projected rise in global temperatures will shift runoff patterns of snowmelt dominated basins, resulting in earlier spring peak flows and reduced summer runoff. Projections of future runoff are beneficial in preparing for climate change induced changes in streamflow, which may necessitate the construction of additional artificial reservoirs to compensate for the reduced natural storage in the form of snow. In this study, the Snowmelt Runoff Model (SRM) was applied to projecting future runoff in the Upper Athabasca River after assessing its ability to simulate historical flows in the basin. SRM utilizes the data-light degree day approach to modelling snowmelt, assuming melt to be proportional to the temperature above freezing through the degree day factor (DDF). Nevertheless, the model performed very well in simulating flows over both the calibration (2000-2002) and validation (2003-2010) periods. The inclusion of a separate DDF for glaciated areas was found to be essential in accurately simulating over multiple years with varying snow conditions. The increased melt rate of glacial ice due to its lower albedo relative to snow could explain most of the elevation dependence of the DDF. The SRM with glacier component was applied with four future (2070-2080) climate change scenarios representing uncertainty in climate change projections over the basin. The results show a consistent pattern of change in runoff across all scenarios, with substantial increases in May runoff, minor increases over the winter months, and decreased runoff in summer months (June-August). Projected flows are consistent with past modelling studies for the region and with historical trends. In general, the SRM performed very well in simulating historical flows and provides useful runoff projections despite the relative simplicity and few input variables of the model.



Hydrology, Athabasca River, Modelling, Snowmelt, SRM