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Monique Keiran: Why monitoring faraway mountain reservoirs is important

Freshwater storehouses refresh rivers with cool, plentiful water in months when air temperatures are high and water levels tend to be at their lowest
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Snowpack on the Olympic Mountains. Researchers are using aircraft-based remote sensing to accurately ­determine seasonal snowpack across entire watersheds in the province, as part of a project out of the University of Northern B.C., 91ԭ Island University and the Hakai Institute, writes Monique Keiran. DARREN STONE, TIMES COLONIST

We’ve become accustomed to hearing about how much freshwater is available in our community drinking-water sources.

The Capital Regional District has monitored the water amounts in the Sooke and Goldstream reservoirs for years, publishing weekly summaries.

Other regional districts, including the Cowichan ­Valley Regional District and Metro 91ԭ, also report on their reservoir levels, and the ­federal ­government monitors and provides real-time ­measurements of flows in the province’s rivers.

In tracking those metrics, regional governments and the province can base directives and guidelines for use on evidence and emerging trends. They can more easily justify the Stage 1 water restrictions applied annually in this region or the Stage 3 and 4 restrictions ­implemented in much of B.C. last summer.

They can identify and quickly estimate impacts of water main breaks, as happened last week in ­Calgary. They can better assess community, safety and ­ecosystem impacts and determine when additional treatment levels or boil-water advisories are needed.

Humans measure what we value. We also value what we measure. The very act of measuring confers ­perceived value to whatever it is we’re measuring. If we pay that much attention to something, well, it must be important.

But the real value in measuring comes with ­knowledge. If we don’t know how much there is of something, it’s easy to assume more exists than actually is available or that supplies are easier to replenish than they actually are.

Water has always been important to and for humans. Despite this, it’s only relatively recently that regularly measuring its availability, quantity and quality has been deemed important in much of North America.

In B.C., the monitoring has been restricted mostly to local and regional scales.

That approach is shortsighted. Rivers tie the ­province’s high mountain peaks to its lowlands and coasts, often hundreds of kilometres away. The ­mountains’ seasonal snowpacks and glaciers serve as freshwater reservoirs for farms, forests and ­communities along the rivers’ lengths.

Those freshwater storehouses buffer downstream ecosystems by refreshing rivers with cool, plentiful water in months when air temperatures are high and water levels tend to be at their lowest.

Thanks to a project out of the University of ­Northern B.C., 91ԭ Island University and the Hakai ­Institute, the health, quantity and mass of faraway mountain reservoirs has been monitored in recent years. Researchers are using aircraft-based remote sensing to accurately determine seasonal snowpack across entire watersheds in the province.

The plane flies over watershed areas when there is no snow to obtain bare Earth measurements and again when there is snow.

Researchers then subtract the no-snow ­measurements from the snow measurements to ­estimate snow depths across entire landscapes that are otherwise difficult to access, particularly in winter.

On-the-spot snow and ice core sampling provides snow density information that, combined with the ­snow-cover estimates, yields the mass of snow and ice.

“We can get a number now for how many ­million cubic metres of water are stored in the snowpack,” says Bill Floyd, a B.C. Ministry of Forests research ­hydrologist and 91ԭ Island University ­geography adjunct professor involved in the study.

“We’ve been able to show in these watersheds that snow makes up a significant component for the five years we’ve measured.”

The data provides snowpack storage amounts for all the watershed sites they’ve studied, allowing ­water-supply managers to assess and balance water needs and determine water-restriction levels and ­timing.

The project also allows the researchers to assess how important the glaciers are for runoff, how these frozen reservoirs are changing through time as climate warms, and even how soot from recent wildfires affects melt rates and timing.

Measuring isn’t enough, of course. Once critical resources, including freshwater, are shown to be depleting, action to safeguard them is also needed.

According to a 2023 study out of the University of Northern B.C., 80 per cent of Western Canada’s glaciers will disappear by the end of the century.

By analyzing 440,000 satellite images, the researchers concluded about half the world’s glaciers are expected to disappear within 80 years, with B.C.’s smaller ice masses among the first casualties.

Without reliable distant snowpacks and ice ­reservoirs to feed our rivers, the impacts of local ­summer temperatures and drought will become ­magnified and ever-available clean drinking water will become less reliable.

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