Monday, September 27, 2010

Glacier melt and water supply in North America

We often here about glacier melt in Asia threatening the water supply for the downstream population. Faux controversies about a single line in the IPCC reports aside, the potential decline in South Asian water flows is certainly a critical concern given the hundreds of millions of people dependent on those rivers.

It is easy to forget that many North American communities, particularly in the Canadian prairies, also depend on water that originates in mountain glaciers. Case in point, the stunning figure at right.
The shows the model-calculated river discharge of the North Saskatchewan River (at Whirlpool Point), which flows across Alberta and Saskatchewan, with (light blue) and without (dark) blue the contribution from glaciers in the Rockies. The figure was reproduced by Natural Resources Canada from an article by Comeau et al. in Hydrological Processes.

The key change, obvious from the figure, is that without the glacial water source, there will be a huge decrease in summer water flows. The result is a more typical snowmelt-dominated hydrograph (chart of seasonal river discharge), similar to something you'd see in another part of the continent.


Ed Davies said...

Why isn't there a corresponding increase in winter flows without the glaciers? Surely winter rainfall would just run off.

Simon Donner said...

This is based on melt contribution to streamflow. As far as I know, the study did not evaluate the overall impacts of climate change (i.e. more winter rains). Regardless, you'd still get a hydrograph with a springime peak and low summer flows.

EliRabett said...

There is a similar problem in S. American w. the Andes

davidwwalters said...

Ed, I don't think there is much rainfall, and hence runoff in Canada during winter.