Jennifer Lento, Wendy Monk,Tim Jardine, Fuad Olokunola, Mustakim Ali Shah, Haley Carlson, Saman Razavi (2022). Understanding environmental flow needs in the Saskatchewan River basin. Proceedings of the GWF Annual Open Science Meeting, May 16-18, 2022.

The quantity, quality, and timing of freshwater flow that is needed sustain aquatic life and ecosystem function can be described by environmental flows. Management that aims to maintain environmental flows that sustain a healthy ecosystem will in turn support the ecosystem services that humans derive from freshwaters. Our goal was to characterize flow conditions in the Saskatchewan River Basin to better understand how components of environmental flows may be affected by flow alteration and predicted future flow scenarios. We compared discharge data from gauges throughout the basin with estimates of naturalized flow (expected discharge in the absence of flow alteration) and predicted future flows under 15 climate scenarios, with adjusted flow estimates from MESH for the periods 1979-2010, 2025-2055, and 2070-2100. Based on the estimated naturalized flow conditions, we developed presumptive standards of flow, which can be used as a conservative estimate of acceptable flow alteration to preserve ecological integrity. When compared with measured flows from 1979-2010, the presumptive standards indicated that flow regulation has resulted in higher flows in the winter and lower flows in the summer, reducing the seasonality of the hydrograph and potentially impacting ecosystem function and biodiversity through loss of environmental cues. This difference in the magnitude and timing of measured flows from estimated naturalized flows was further described using Indicators of Hydrologic Alteration, which include variables that estimate components of environmental flows such as peak and low flows. Together, these approaches form the foundation for an environmental flow framework for the Saskatchewan River basin, describing flow needs within the system and allowing for the integration and testing of ecological flow hypotheses.

AOSM2022 IMPC First Author: Jennifer Lento, University of Saskatchewan Additional Authors: Wendy Monk, Environment and Climate Change Canada; Tim Jardine, University of Saskatchewan; Fuad Olokunola, University of Saskatchewan; Mustakim Ali Shah, University of Saskatchewan; Haley Carlson, University of Saskatchewan; Saman Razavi, University of Saskatchewan