Presumptive standards for river flows under future flow scenarios

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Flow data from the MESH model were used to develop presumptive standards for flow at 35 hydrologic gauge stations in the Saskatchewan River basin. Data used were daily flows from 1979-2010 (historic gauge data) and MESH flows with no management under 15 climate scenarios for the time periods 1979-2010 (e.g., naturalized historic flow), 2025-2055 (naturalized future flow), and 2070-2100 (naturalized future flow). For each climate scenario, calculations for presumptive standards included median, minimum, maximum and standard deviation of flow, median +/- 5%, 7.5%, 10%, and 20%, Q95, seasonal Q95, seasonal Q75, seasonal Q50, and seasonal Q10, deviation of actual flow from naturalized, and % deviation of actual flow from naturalized. Flow and presumptive standards were plotted.

Data are used for IMPC Theme B: Water Management Modelling, Coupling Human-driven and Natural Systems. The data contribute to IMPC subtheme B2: Developing a performance model for aquatic ecosystems based on hydro-ecologic metrics and environmental demands.

Presumptive standards provide guidelines for acceptable flows to maintain ecosystem function. Using naturalized flows, i.e., flows with the effects of anthropogenic activities removed, we calculated these flow guidelines for 35 stations in the Saskatchewan River basin, based on estimates from 1979-2010. These naturalized flows were compared with actual flow over the same period to examine deviations from expected flows in the absence of human activity. Naturalized future flows under 15 climate scenarios were also examined to evaluate how flow is expected to change, and what impact that will have on seasonality, timing, and magnitude of flows.

35 National hydrologic gauge stations in the Saskatchewan River Basin in Saskatchewan, Alberta, and Manitoba