Water 2021, 13, 2425. https://doi.org/10.3390/w13172425 www.mdpi.com/journal/water Article Ensemble Projection of Future Climate and Surface Water Supplies in the North Saskatchewan River Basin above Edmonton, Alberta, Canada Muhammad Rehan Anis * and David J. Sauchyn The Prairie Adaptation Research Collaborative, Suite 219-2 Research Drive, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada; sauchyn@uregina.ca * Correspondence: rehan.anis@uregina.ca; Tel.: +1-(306)-250-5773 Abstract: Changes in temperature and precipitation are expected to alter the seasonal distribution of surface water supplies in snowmelt-dominated watersheds. A realistic assessment of future climate change and inter-annual variability is required to meet a growing demand for water supplies in all major use sectors. This study focuses on changes in climate and runoff in the North Saskatchewan River Basin (NSRB) above Edmonton, Alberta, Canada, using the MESH (Modélisa- tion Environnementale communautaire—Surface Hydrology) model. The bias-corrected ensemble of Canadian Regional Climate Model (CanRCM4) data is used to drive MESH for two 60-year time periods, a historical baseline (1951–2010) and future projection (2041–2100), under Representative Concentration Pathway (RCP) 8.5. The precipitation is projected to increase in every season, there is significant trend in spring (0.62) and fall (0.41) and insignificant in summer (0.008). Winter extreme minimum temperature and summer extreme maximum temperature are increasing by 2–3 °C in the near future and 5–6 °C in the far future. Annual runoff increases by 19% compared to base period. The results reveal long-term hydrological variability enabling water resource managers to better prepare for climate change and extreme events to build more resilient systems for future water demand in the NSRB. Keywords: ensemble modeling; land surface hydrological model; climate change; extreme runoff change 1. Introduction A shift in the seasonal distribution of surface water supplies, and in the frequency and severity of flooding and drought, are among the most problematic regional impacts of global climate change [1–3]. These impacts are especially challenging in water-limited landscapes and where watershed hydrology is dominated by the melt of a cold season snowpack. Both of these geographic characteristics apply to the mid- and high-latitude snow-dominated river basins of western Canada. This region has also been subject to considerable climate change. Since 1948, Canada has warmed at twice the global rate; while in western Canada, the increase in temperature has been about three times more rapid than global warming [4,5]. As a result, the flow of rivers draining the eastern slopes of the Canadian Rocky Mountains has declined in recent decades [6–12]. Over the same period, there has been a growing demand for water supplied from the Rocky Mountains of western Alberta. This province has a population of about 4.3 million. It also has most of Canada’s oil and gas industry and irrigated agricultural land. While the Rocky Mountains are the water towers of the western interior, most of Alberta is sub- humid, with large seasonal and inter-annual variability and extreme weather typical of a mid-latitude continental climate. Out of the 20 most damaging weather events in Canadian history, 16 occurred in Alberta [13]. Citation: Anis, M.R.; Sauchyn, D.J. Ensemble Projection of Future Climate and Surface Water Supplies, North Saskatchewan River Basin above Edmonton, Alberta, Canada. Water 2021, 13, 2425. https://doi.org/10.3390/w13172425 Academic Editor: Aizhong Ye Received: 09 July 2021 Accepted: 31 August 2021 Published: 3 September 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and insti- tutional affiliations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses /by/4.0/).