Managing water in complex systems: An integrated water resources model for Saskatchewan, Canada

• We developed an integrated water resources model with dynamic irrigation demand and economic evaluation components.
• Irrigation demand estimation is sensitive to the selection of reference evapotranspiration algorithm.
• Irrigation expansion would increase the total direct economic benefits to Saskatchewan.
• Indirect costs of irrigation expansion include reduction in lake levels and river flows in Saskatchewan.

Using a system dynamics approach, an integrated water resources system model is developed for scenario analysis of the Saskatchewan portion of the transboundary Saskatchewan River Basin in western Canada. The water resources component is constructed by emulating an existing Water Resources Management Model. Enhancements include an irrigation sub-model to estimate dynamic irrigation demand, including alternative potential evapotranspiration estimates, and an economic sub-model to estimate the value of water use for various sectors of the economy. Results reveal that the water resources system in Saskatchewan becomes increasingly sensitive to the selection of evapotranspiration algorithm as the irrigation area increases, due to competition between hydropower and agriculture. Preliminary results suggest that irrigation expansion would decrease hydropower production, but might increase the total direct economic benefits to Saskatchewan. However, indirect costs include reduction in lake levels and river flows.