Concordia study finds snow droughts in western and southern Canada could affect nearly all Canadians

(Press-News.org) Researchers at Concordia have developed a new method of measuring the amount of usable water stored in snowpacks. The comprehensive technique, known as snow water availability (SWA), uses satellite data and climate reanalysis techniques to calculate snow depth, snow density and snow cover across a wide swath of Canada and Alaska.

“SWA quantifies how much water is available where snowpack exists. Knowing where the snowpack is located is critically important because where its water ultimately ends up after melting depends on where the snowpack was initially located,” says the study’s corresponding author Ali Nazemi, an associate professor in the Department of Building, Civil and Environmental Engineering at the Gina Cody School of Engineering and Computer Science.

Data gathered using this methodology shows that usable snow water has declined sharply in areas of the Canadian Rockies, where major river headwaters originate. These areas make up only three per cent of the country, but when combined with smaller declines elsewhere, the changes affect a quarter of Canada’s land mass and 86 per cent of the population. Nazemi warns that the consequences touch agriculture, hydropower, shipping, recreation and Indigenous communities.

“This is a creeping drought, a drought that can be very difficult to detect until you are in the middle of a crisis,” he says. Past droughts in southern Ontario and Quebec (2012) and in western Canada (2015) illustrate how quickly water shortages can escalate.

The findings were published in the Nature journal Communications Earth & Environment.

Getting dry high and low Changes in snowpacks were most evident in mid-elevation regions of the Rockies. Snow depth loss emerged as the main driver of SWA decreases in these areas.

The Okanagan–Similkameen drainage region in the British Columbia interior, the Assiniboine–Red River in Saskatchewan and Manitoba, and the vast Saskatchewan River basin — which runs from the Rockies across the Prairies to Lake Winnipeg and beyond — were the most affected.

The compact, densely populated Okanagan-Similkameen region is heavily reliant on mountain snowpack melt to meet its water needs. Snow storage in the area was shown to have dropped drastically over the two-decade study period.

Meanwhile, the Assiniboine-Red and Saskatchewan River basins show the cumulative effect of small drops in snow cover across large land areas. The researchers say these findings reveal how seemingly insignificant SWA losses can eventually have serious consequences.

More snow in north, less water in south Unlike traditional methods for measuring water stored in the snowpack, SWA captures rapid changes in snow cover at the beginning and end of the snow season. By analyzing snow depth, density and cover on 25 by 25 km2 grids — roughly 18,000 of them, covering 4.5 million km2 — the researchers captured regional subtleties such as slopes, terrain types and uneven snow cover distribution in annual, seasonal and monthly time scales.

Nazemi points out that despite popular belief, total SWA across Canada has actually increased, particularly in northern regions and near to the Arctic coast. Warmer temperatures have caused Arctic Ocean ice to recede, releasing more moisture into the atmosphere. That moisture can fall as snow in cooler inland areas, but it does not necessarily contribute to the hydrological cycle that supports Canadian populations and socio-economic activities.

“The asymmetric effect of this drought — in which a three per cent significant drop in SWA can impact 26 per cent of the land containing 86 per cent of the population — shows that this requires a re-evaluation of our water management system,” Nazemi says.

Robert Sarpong, MASc 2025, and Amir AghaKouchak of the University of California, Irvine, contributed to this study.

This research received funding from Canada’s New Frontier Research Fund—Exploration and the Natural Science and Engineering Council Discovery grant program.

Read the cited paper: “Creeping snow drought threatens Canada’s water supply”

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