Columbia Icefield

Glaciers play a small but important role in providing water to many of Alberta's major rivers. Rivers with some significant icefields and large glaciers in their headwaters include the Bow River, the North Saskatchewan River and the Athabasca River. Others, such as the Oldman and Red Deer Rivers, have few significant glaciers in their watersheds. Studies have shown that the melting of glacier ice and glacial retreat contributes a relatively small proportion of the annual water supply in Alberta's larger mountain-fed rivers. Most of the river flow in catchments like these come from the annual mountain snowmelt runoff, plus from summer precipitation. However, after mountain snowpacks have melted significantly, river flows decline into the summer months and will depend heavily on rainfall for their flows. It is during these times, and especially during dry years when there is relatively warm weather and little rainfall, that the amount of flow derived from the melting of the glaciers can become more significant. Glacial meltwater in dry years can help maintain the flows in the river at a higher rate, and much later into the season, than would otherwise occur.

Toe of Columbia Icefield

What can we expect if the glaciers disappear?
Glaciers and glacial processes continue to be an important area of active study. Many people have noted that the glaciers have been retreating at an accelerated rate for more than a century. Studies from the North Saskatchewan River indicate that for the past 50 years as the glaciers have continued to retreat, their average contribution to downstream (their percentage of the overall flow) has also been declining. No one is certain when or if the glaciers and icefields might disappear entirely but it is expected that if they continue to shrink, the water derived from them will also continue to decline. On an average annual basis however, the change is likely to be modest since net wastage of glacial ice is not a very large component of the annual water balance of rivers. However, as described earlier, glaciers can have mitigating effects on a seasonal basis and in dry years since they contribute to base river flows. Therefore, their decline or disappearance must be considered in water management actions and for assessing water supplies. This is of greater importance in the southern portion of the province where the demand for water resources is approaching the limits of its availability.

The implications of continued glacial retreat and possible climate change are still being actively researched. As more information and knowledge about glaciers and their importance to our environment is developed, we will be using it to help us make the best environmental and management decisions about Alberta's water.