Integrated water resource management under water supply and irrigation development uncertainty

The Saskatchewan River Basin (SaskRB) in Saskatchewan, Canada, supports various water demands including municipal, industrial, irrigated agriculture, hydropower and environmental sectors. Proposals for future development include significantly increased irrigation. However, proposing an appropriate level of irrigation development requires incorporation of water supply uncertainties in the water resources management analysis, including effects of climate variability and change. To evaluate potential climate change effects, a feasible range of shifts in annual volume and peak timing of headwater flows are considered to stochastically generate flows at the Alberta/Saskatchewan border. This envelope of flows, 30,800 realizations, is further combined with various irrigation expansion areas to form various future scenarios. Using an integrated water resources model developed for Saskatchewan, the impact of irrigation development on the system is assessed under the changing water supply conditions. The results of this study show that level of irrigation development as well as variation in volume and peak timing of flows can all contribute to change the water availability, vulnerability and economic productivity of the water resources system in Saskatchewan. In particular, the combined effect of large irrigation expansion, reduction in the volume of flows and earlier timing of the annual peak can exacerbate water resources system vulnerability, produce unstable net revenues, and decrease flood frequency in the Saskatchewan River Delta.