The North Saskatchewan River Basin (NSRB) exhibits significant spatial variability in temperature and precipitation, both within any given year and from year to year. In the mountains and higher foothills, precipitation tends to be relatively high and evapotranspiration low, resulting in high water yield.
In contrast, in the eastern portion of the NSRB, average annual precipitation tends to be less than average annual evapotranspiration, which leads to large moisture-deficit areas, either at certain times of the year or regionally during multi-year droughts.
Given the geographic variability in precipitation, evaporation, and other climatic variables, it is critical for an assessment of water yield to consider explicitly the spatial variability of the factors contributing to water yield.