April 28, 2021 1-2PM ET: SYP Water Talks: Andrew Tefs, From dam operations guides to flow signatures: Large-scale, long-term regulated and re-naturalized hydrologic modelling in the Hudson Bay drainage basin

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This work focuses on three phases of a larger examination of the effects of climate change and hydroelectric regulation on streamflow: improving reservoir regulation in a hydrologic model, reconstruction of a pre-development hydrologic model, and analysis of the impacts of regulation and climate change using multiple flow signatures and a multi-metric analysis. Process-based hydrologic modelling of real-world dam operations presents many challenges. Namely, that processes governing reservoir relationships between inflow, storage, and outflow vary between reservoirs, inter-annually for a given reservoir, and often intra-annually for a given reservoir as well. We present a framework to evaluate multiple stepwise formulations of reservoir outflow for a five-zone reservoir discretized by intra-annually variable operational levels and then to select an optimal formulation for any reservoir. To evaluate long-term effects of anthropogenic changes to the hydrologic system (dams, diversions, etc.), we test the effects of climate change and reservoir regulation jointly and separately. In order to test a “what-if” (or counterfactual) hydrologic model wherein no hydroelectric development had taken place in the Nelson-Churchill River Basin and La Grande Rivière Complex, we develop a hydrologic model “re-naturalized” by landcover (using pre-flooding surface area imagery) and lake outflow (using pre-development stage-outflow relationships). The ability to distinguish the impact of regulation in historic records by multiple means is applied to an assessment of the likelihood of convergent or divergent behaviour of regulated and re-naturalized basins under a changing climate. We analyze both our regulated and re-naturalized results using a framework including a suite of flow signatures, spectral and wavelet analyses, and trend analysis.


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Bio: Andrew Tefs is a research associate working for the Hydrologic Analysis Lab at the University of Calgary. He graduated with a BSc and MSc in Civil Engineering from the University of Manitoba. He has worked in various research positions across numerous projects since 2015 for the UofM’s departments of Civil Engineering, Animal Science, Biosystems Engineering, and Centre for Earth Observational Science, the UofC’s department of Geography, and the University of Alberta’s department of Earth and Atmosphere Sciences.