How reliable are Canadian Mountain Water Supplies under a Changing Climate?
By Kabir Rasouli
Mountains function as water towers for agriculture, industry, and communities across Western Canada. Ongoing climate change is resulting in reduced seasonal snow cover and an earlier rise in spring runoff and peak flows in mountain streams. Understanding how water resources are affected by climate is important for water and energy security, flood control, and operation of development projects.
Researchers from the University of Saskatchewan and Centre for Hydrology collected data from mountain weather stations in the Yukon Territory and Canadian Rockies to model snow accumulation, snowmelt, and streamflow for assessing the sensitivity of hydrological processes to climate and vegetation changes. They found that several aspects of mountain hydrology, including snow accumulation and peak streamflow, are highly susceptible to warming and precipitation patterns. Snow accumulation is particularly sensitive to warming, with average snow depths across study basins expected to decrease by 52–55% with warming of 5°C and a 20% decline in precipitation. However, the effect of warming on snowpacks may be partly offset if precipitation increases, especially at northern latitudes.
Researchers also found that mountain hydrology is influenced by the upward expansion of trees and shrubs into alpine meadows. For example, a greater density of trees intercepting falling snow alters snowmelt dynamics, with consequences for downstream runoff. These results demonstrate the complexity of climate and land cover interactions affecting mountain hydrological processes. Further, this study highlights the sensitivity of water resources in Western Canada, where managers will have to balance future water demands with a potentially dwindling supply.
This is a summary article authored by Kabir Rasouli and edited by Charlie Loewen. For further information, please see the original published research:
Kabir Rasouli, John W. Pomeroy, J. Richard Janowicz, Sean K. Carey and Tyler J. Williams (2014) Hydrological sensitivity of a northern mountain basin to climate change. Hydrological Processes, 28: 4191–4208 (doi:10.1002/hyp.10244).