Rivers impacted by hydroelectricity generation are seeing fewer fluctuations in flow according to a new paper studying the phenomenon of hydropeaking. 

Authored by University of Northern British Columbia (UNBC) Environmental Science Professor Dr. Stephen Déry, Marco A. Hernández-Henríquez from UNBC, Tricia A. Stadnyk from University of Calgary and Tara J. Troy of the University of Victoria, the study looked at 500 sites across Canada and the US over 100 years and showed river flows have become increasingly more consistent, suggesting aquatic species are benefiting from fewer peaks and declines in river flows on waterways with hydroelectric infrastructure.

Déry and his collaborators studied the phenomenon of hydropeaking, when water levels in managed rivers rise or fall sharply due to increases or decreases in electricity demand. The paper, Vanishing weekly hydropeaking cycles in American and Canadian rivers, published in Nature Communications, details the decline of hydropeaking in recent years. 

“There is a very consistent, overall decreasing pattern in the index values we’ve formulated for hydropeaking in this study, and the pattern crosses various jurisdictions, watersheds, and power grid interconnections,” Déry said. “A reduction in ramping up and ramping down in river flows benefits aquatic species and improves their habitat.” 

The study found instances of hydropeaking increasing in the mid-20th century and then decreasing in the 21st century.  “The results suggest that hydroelectricity demand and generation is changing, with less reliance on hydropower to support peak demand during daytime and weekdays,” Déry said.

Other reasons that could be contributing to the decrease in hydropeaking, according to the researchers, are the addition of more wind and solar energy to the grid, improved regulatory oversight, an increasingly interconnected grid that helps balance out the load and lifestyle changes that have resulted in more even electrical demand.

The findings can help hydroelectric companies refine their operations to further reduce the impact on aquatic life, said Déry: “Hydroelectric companies are all keen to understand how their operations are evolving with the goal of reducing their impacts on the environment. Recent reductions of the weekly hydropeaking cycle provide evidence that hydropower operations are indeed being modified to improve ecosystem health and well-being.”

This study looked at data between 1920-2019, and Déry says the next phase of the work will examine the impact the COVID-19 pandemic had on regulated bodies of water.  

“Our preliminary analyses suggest a substantial decline in 2020 of the weekly hydropeaking index values as electricity demand diminished during the pandemic,” Déry said. “As well, we will be assessing the seasonal variation in hydropeaking and overall extremes. We also hope at some point to directly correlate electricity production with weekly hydropeaking cycles.”