Researchers from Wilfrid Laurier University say it’s not how much snow falls, but how it melts, that dictates how much water will end up in Yellowknife’s hydro reservoirs.

The question is important because when hydro levels are too low, the city must switch to diesel fuel – which is both expensive and environmentally unfriendly.

Better understanding of the Snare hydro system, north-west of Yellowknife, could improve forecasting of water levels and lead to more efficient management of hydro in the future.

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“What we have found is that it doesn’t matter so much how much snow we get, it’s more about the timing of the snowmelt and how intense the snowmelt is,” said Wilfrid Laurier researcher Jenny Hickman.

“We want to reduce the amount of water that’s infiltrating into the ground and being allocated towards storage, because that’s water that can’t be used for generating power.

“When you have a really fast, early snowmelt – when the ground is still totally frozen – you get higher run-off, your basin efficiency is higher, you get more water in your rivers, and your reservoirs are full.”

That means a swift switch from a cold winter to quite a warm spring is ideal for resupplying hydro reservoirs, but Hickman says it’s too early to establish the effect 2018’s stop-start spring will have.

In 2014 and 2015, the territorial government had to find $60 million in subsidies to offset the cost of additional diesel when hydro failed – much of that coming as a result of low water levels.

To reach its conclusions, the university team studied records from 1999 to 2015 while conducting snow surveys to corroborate GlobSnow satellite data.

“During that period of time there’s been a fairly good range of climate conditions, so we can say with a bit of confidence that what we’re seeing is probably reasonably correct,” said Professor Mike English, who helped to lead the research.

The team hopes to add instrumentation to the Snare River basin this summer, having expressed surprise that basic instruments like precipitation gauges are currently lacking.

Those instruments will allow scientists to build a more accurate picture of what’s happening in the basin, and refine our ability to predict how much water will be available for hydro use in future years.