Analyses of climate change impacts in the South Saskatchewan River subbasins: from headwaters to Saskatoon

Abstract

Winter warming, changes in the regimes of snowmelt and glacial melt, and impacts of water diversions and regulations in Alberta and Saskatchewan, are collectively, likely to affect annual and monthly volume and timing of the South Saskatchewan River Basin. These aspects are evaluated by assessing possible impacts of climate change in this basin, different stations were selected, covering headwaters/mountainous areas and areas in the Prairies, where simultaneous changes in snowpack accumulation and streamflows are quantified. This research reveals that in most of the stations, an historic decline in annual naturalized flows, and summer flows were evident, while regulated flows showed an increase in winter months (January and February). A number of models (e.g. Thornthwaite, Meyer and Hargreaves methods) were employed determination of evapotranspiration in Lake Diefenbaker, from which Meyer provided good results, although due to its complexity, the Thornthwaite is recommended to analyze future projections of ET in the Lake. Annual ET was found to be around 815 mm, which represents a water loss in the Lake of approx. 5% in normal conditions (not dry years) and in dry years it can reach up to 7%. According to future projections, ET is expected to increase 20%, reaching an annual value of 905 mm.