Hydrological Regime Responses to Climate Change for the 2020s and 2050s Periods in the Elbow River Watershed in Southern Alberta, Canada

Abstract

The Elbow River watershed, located in southern Alberta, drains approximately 1,235 km2 area, and supplies the Glenmore Reservoir that provides water to nearly half of Calgary, a fast growing city of 1.1 million inhabitants. The watershed is characterized by a complex hydrological regime and is typical of snow dominated basins, with a spring freshet driven by snow melt and rainfall in late spring and early summer. This context creates favorable conditions for springtime flooding, which resulted in extensive damage in 2005 and 2013. Therefore, understanding how future climate changes might influence the watershed hydrological regime is critical. This research was conducted to investigate the hydrological regime responses of the watershed to climate change for the period of 2020s (2011--2040) and 2050s (2041--2070), relative to 1961--1990. The physically-based, distributed MIKE SHE/MIKE 11 model was used to simulate hydrological processes based on a warmer and drier (CCSRNIES A1FI) climate scenario. Results reveal that the average annual overland flow, baseflow, and river flow will decrease over the next 60 years and that this decrease combined with a drastic increase in evapotranspiration might increase water scarcity. Peak flows will increase in the winter and early-mid spring while decreasing in the summer and early fall. This enhances the risk of flooding in the spring, especially in the month of April which exhibits a significant increase in rainfall coinciding with the highest increase in spring freshet.