Hydrologic Impacts of Projected Climate in the Athabasca Watershed: Implication on Water Availability in the Region

English Abstract:

The potential impact of projected climate change on the hydrologic regime of the Athabasca watershed in Alberta, Canada, is examined using the process based and distributed hydrologic modelling system, MIKE-SHE. High resolution climate data statistically downscaled from the latest Coupled Model Inter comparison Project phase 5 (CMIP5) global climate projections was used as climate forcings to the hydrologic model. Analysis of the multiple climate change projections derived from six GCMs, two statistical downscaling techniques and two emission scenarios, showed an overall increase in projected temperature and precipitation in the region for all seasons except the summer that has shown both increases and decreases in temperature and precipitation, depending on the specific climate model and scenario considered. The watershed's response to these climate change scenarios is also assessed by computing hydrologic indicators that represent the magnitudes and timings of the hydrologic regime from the simulated discharges, to identify possible alterations between the baseline (1971-2000) and the two future periods (2050s, and 2080s). The results show overall projected decreases in mean monthly and annual maximum snow water equivalent (SWE) over the basin, with the biggest decreases in the upper reaches; and an overall increase in the actual evapotranspiration (AET) with the highest increases in the middle and lower reaches. The results also show future increases in winter and spring flows at most hydrometric stations considered within the basin, with relatively higher increases being projected for the stations located at the upper reach. On the contrary, summer flows are projected to decrease at most of the stations because of earlier snow-melt, increased evapotranspiration and no significant increase in summer precipitation. Implications of the projected changes in the hydrologic regime on water availability in the region are also identified.