EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Vanishing weekly cycles in American and Canadian hydropeaking rivers

Stephen Dery1, Tricia Stadnyk2, Tara Troy3, and Marco Hernandez-Henriquez1
Stephen Dery et al.
  • 1Environmental Science and Engineering Program, University of Northern British Columbia, Prince George, Canada (
  • 2Department of Geography, University of Calgary, Calgary, Alberta, Canada
  • 3Department of Civil Engineering, University of Victoria, Victoria, Canada

Sub-daily and weekly streamflow cycles termed hydropeaking are common features in regulated rivers across the globe. Weekly periodicity in flows arises from fluctuating hydropower demand and production tied to socioeconomic activity, typically with higher consumption during weekdays followed by reductions on weekends. In this presentation, we will introduce a novel weekly hydropeaking index to quantify the intensity and prevalence of weekly hydropeaking cycles at 368 sites across the United States of America (USA) and Canada over 1920-2019. Our results reveal a robust weekly hydropeaking signal exists at 1.3% of available sites starting in 1920 with a fraction that peaks at 16.7% of sites in 1963. Highly hydropeaking signals then diminish to only 3.3% of available sites in 2019, marking a 21st century declining pattern in hydropeaking intensity across parts of North America. Application of the Mann-Kendall Test reveals 95 locally significant declines in weekly hydropeaking intensity between 1980-2019. Our results can be attributed to diminishing differences between streamflow on weekends versus weekdays in regulated rivers across Canada and the USA. We will conclude the presentation with a discussion on how these findings may be tied to shifts in socioeconomic activity, alternative modes of electricity production, and legislative and policy changes impacting water management in regulated systems.

How to cite: Dery, S., Stadnyk, T., Troy, T., and Hernandez-Henriquez, M.: Vanishing weekly cycles in American and Canadian hydropeaking rivers, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-953,, 2021.

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