Glacier contribution to the North and South Saskatchewan Rivers

Abstract The hydrological model WATFLOOD and a separate volume–area scaling relationship are applied to estimate glacier wastage and seasonal Melt contribution to the North and South Saskatchewan Rivers originating in the Canadian Rocky Mountains (1975–1998). Wastage is the ice melt volume that exceeds the volume of snow accumulation into the glacier system in a hydrological year, causing an annual net loss of glacier volume. Melt is the ice melt volume that is equal to, or less than, the volume of snow that accumulates into the glacier system in a hydrological year. By our definition then, glacier Melt is a storage term and does not contribute to increased total annual streamflow. Water is stored as snow on accumulation into the glacier system, and the water equivalent runoff is delayed until ice melts in the late summer months of the otherwise low streamflow. Wastage varied between basins with similar glacierized areas reflecting the individual response of glaciers to climate, contributing over 10% to July‐to‐September streamflow in some headwater basins, but under 3% annually to the regulated flow at Edmonton and Calgary. Melt was positively correlated with basin glacierized area and contributed over 27% to July‐to‐September flow from basins with greater than 1% glacierized area, and over double the wastage volume at Edmonton and Calgary. Future glacier decline is therefore expected to result mainly in an advancement of peak flow towards a non‐glacierized snowmelt regime hydrograph, resulting in significantly reduced late summer flows further reduced by decreasing wastage contributions. Copyright © 2009 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.