Potential combined hydrologic impacts of climate change and El Niño Southern Oscillation to South Saskatchewan River Basin

- We modelled future streamflow of South Saskatchewan River Basin (SSRB) of Alberta.
- We investigated combined impact of climate change and El Niño Southern Oscillation.
- Under the impact of climate change, the streamflow of SSRB is expected to decrease.
- Combined impact of climate change and El Niño cause further decrease in streamflow.
- Combined impact of climate change and La Niña would reduce the decrease in streamflow.

SummaryA physically based land surface scheme, the Modified Interaction Soil Biosphere Atmosphere (MISBA) of Kerkhoven and Gan (2006) was used to assess the future streamflow of the South Saskatchewan River Basin (SSRB) of Alberta under the combined impacts of climate change and El Niño Southern Oscillation (ENSO). Potential impacts of climate change on the streamflows of 15 sub-basins of the SSRB for the 2010-2039 (2020s), 2040-2069 (2050s) and 2070-2099 (2080s) were simulated by MISBA based on 30 years (1961-1990) of re-analysis data of the European Centre for Mid-range Weather Forecasts (ERA-40) adjusted with climate scenarios projected by four General Circulation Models (GCMs) for three Special Report on Emissions Scenarios (SRES) emissions (A1FI, A21, B21) of Intergovernmental Panel on Climate Change (IPCC). Next, the combined impacts of climate change and ENSO are simulated by driving MISBA with the ERA-40 dataset re-sampled for active El Niño and La Niña episodes adjusted for climate projections of 2050s. Under SRES climate projections alone, MISBA simulated an overall decrease in streamflow for sub-basins of SSRB in 2020s, 2050s, and 2080s. While under a combined impact of climate change and ENSO, a further decrease (increase) in the streamflow of SSRB by 2050s was simulated if the climate anomaly considered was El Niño (La Niña).