Climate Change Impacts in the Elbow River Watershed

The Elbow River Watershed originates in the foothills of the Rocky Mountains and is a primary source of water for the City of Calgary. Consequently, the long-term protection and investment of this resource is a primary interest to the City of Calgary. While droughts and water shortages are a serious concern to Albertans, spring freshet flooding may lead to enormous costs virtually overnight. The impacts of climate change on spring flooding in the Elbow River Watershed were determined using both a statistical analysis of historical hydro-climatological data and a modelling analysis using the Canadian Regional Climate Model (CRCM) forcing to the SSARR Watershed model, which is used by Alberta Environment for flood forecasting. Statistical analyses revealed that there were significantly increasing trends in annual mean temperature in the eastern most part of the watershed (+0.007°C/yr) caused by significant trends during February and March only. Significantly increasing trends in annual mean temperature in the western portion of the watershed were also observed (+0.056°C/yr) and were primarily due to increases in January, March, April, July and August. There were no demonstrated trends in total annual precipitation but significant decreases in snowfall were observed in the eastern portion of the watershed. Conversely, increases in snowfall were observed in the western portion near the foothills. No significant trends were observed in discharges within this watershed. Modelling spring freshet flooding using the SSARR and CRCM models showed that spring time flooding due to expected increases in precipitation during the month of May can nearly double flood peaks.

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