| Abstract/Description or Keywords |
The Canadian portion of the Columbia River basin, or Upper Columbia River basin (UCRB), which is made up of the sub-basins of the Columbia and Kootenay rivers, has a hydrologic regime dominated by snow and glacier melt that makes it particularly susceptible to climate change. To investigate the influence of climate change on the water balance and streamflow of the UCRB, simulations are made for a 20-member ensemble made up of seven global climate models (GCMs) run under three emissions scenarios (A1B, A2, and B1 (with one exception)) for three future periods (2020s, 2050s, and 2080s) downscaled using Bias Corrected Spatial Disaggregation and simulated via the spatially distributed Variable Infiltration Capacity (VIC) model. To maximize the utility of the VIC model, a process-based distributed model, it is calibrated to 24 sub-basins. Snow water equivalent (SWE) decreases at lower elevations primarily in the southern portion of the UCRB and increases progressively at high elevations in the north from the 2020s to the 2050s to the 2080s based on the mean of seven GCMs run under the A2 scenario. Evaporation increases where adequate moisture is available in the summer months out to the 2080s. Runoff increases strongly in winter and spring and increases moderately in fall in the UCRB. Mean annual streamflow is projected to increase twice as fast in the northern, higher elevation, Columbia River basin than in the southern Kootenay River basin. Projected increases in mean annual flow are greatest under the A2 emissions scenario, ranging from a 9% increase in the 2020s to a 27% increase in the 2080s in the Columbia River at Keenlyside Dam. Changes in the hydrograph for four sub-basins of the UCRB are most pronounced in the 2080s under the A2 emissions scenario with streamflow increases projected in November to May, decreases in July to September, and mixed responses in June and October. The magnitude of peak flows and low flows is projected to increase for most sub-basins, time periods, and scenarios. Such projected changes could be expected to have implications for water resources management in the basin. |
