Methodology

To model Alberta’s water resources we used the hydrologic model Soil and Water Assessment Tool (SWAT) in combination with the Sequential Uncertainty Fitting program (SUFI-2) to calibrate, validate, and perform uncertainty analysis based on the available measured river discharge data.

SWAT is a computationally efficient simulator of hydrology and water quality at various scales. It is a mechanistic time-continuous model that can handle very large watersheds in a data efficient manner. SWAT is developed to quantify the impact of land management practices on water, sediment and agricultural chemical yields in large complex watersheds with varying soils, land uses, and management conditions over long periods of time.

The main components of SWAT are hydrology, climate, nutrient cycling, soil temperature, sediment movement, crop growth, agricultural management, and pesticide dynamics.

The model is already used in the “Hydrologic Unit Model for the United States” (HUMUS), where the entire U.S. was simulated with good results for river discharges at around 6,000 gauging stations. This study is now extended within the national assessment of the USDA Conservation Effects Assessment Project (CEAP).

A more recent large scale SWAT application included the work of Gosain et al., [2006] where twelve large river basins in India were modelled with the purpose of quantifying the climate change impact on hydrology. SWAT is recognized by the U.S. Environmental Protection Agency (EPA) and has been incorporated into the EPA’s BASINS (Better Assessment Science Integrating Point and Non-point Sources). We have used SWAT to model the whole of Africa, and the country of Iran, as well as smaller watershed in Switzerland and China.