More Rain And Less Snow Will Affect Flow For Irrigation

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Alberta must drastically expand its water and snow monitoring information system in the Rocky Mountains to give managers a better chance to take optimum advantage of water, says a resource specialist.

John Pomeroy, a researcher in water resources affected by climate change at the University of Saskatchewan’s Centre for Hydrology, says river flows are declining, and there is more rain and less snow, providing a quicker river system run-off that will come at a cost to irrigation.

Pomeroy told the Alberta Irrigation Projects Association annual conference here that such work is critical because predicted increases in consumption are incompatible with hydrological changes and the prediction of future change.

Irrigated agriculture in southern Alberta relies on the mountain snowpack to produce a slow melt to the river systems. The snowpack is a water reservoir holding back winter precipitation. A lot of that reservoir is released when irrigation water demand is high.

Only reservoirs allow farmers to extend the run-off flow.

“We must do a better job of measurements (of snowpack and precipitation) at high elevations,” Pomeroy said.

Also, that prolonged flow of fresh water into the Hudson Bay is important to the circulation that creates the sea ice cover in the Arctic, and has an impact on the North Atlantic currents.

“There are global implications from fresh water from Western Canada,” said Pomeroy. He said glaciers still contribute to river flows, but that is declining as more glaciers are disappearing with the warming climate.

He pointed to one mountain lake that relies on snowmelt for 60 per cent of new water, 35 per cent from rainfall and five per cent from glacier melt. In that case, the glacier generally takes in water to match what melts into the water flow. A disturbing development is that the period of snow-covered land is declining in many places.

Pomeroy said glaciers are declining in the Rocky Mountains. Peyto Glacier is gone. About 36 per cent of the glaciated area of the South Saskatchewan River basin was lost from 1975-89. And 22 per cent of glaciers feeding the North Saskatchewan River has been lost.

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