Highly flexible hydropower could prove beneficial for downstream ecosystems (LTU October 2020)

– Anton Burman, PhD student, LTU

A team of researchers at Luleå University of Technology has found that the influence on the riverine ecosystems downstream of a hydropower plant when the discharge is allowed to start and stop up to 60 times per day is less than for fewer flow changes per day. The results were published in a special issue of Water on enviornmental fluid dynamics published earlier this year and shines a new light on the importance of the relationship between operating conditions and ecohydraulics.

It is well established that hydropower plants negatively affect the ecosystems in the downstream river. Some problems are directly related to the operating conditions of the power plant. One such phenomenon is “hydropeaking”, which occurs when the discharge from the turbines increases or decreases quickly. By using numerical modelling, the researchers could investigate how different operating conditions affected the water level of the river downstream. The goal of the research consortium HydroFlex is to see how the river downstream would be affected if up to 30 starts and stops per day is allowed to occur.

“Many problems that occur from hydropeaking can be modelled using modern computational methods. For instance, we can investigate how the stranding of salmonoids changes given different operating conditions”, says main author Anton Burman, PhD student in fluid and experimental mechanics at Luleå University of Technology.

“We see in the results that when we have very many flow changes per day the natural inertia of the river dampens the change in water level. This means that problems related to river dynamics like dried spawning habitats and stranding could decrease.”, Anton then adds.

In the future highly flexible hydro power is expected to increase as countries power production becomes more dependent on intermittent power production such as wind- and solar-power.

“Hopefully, the ecosystems downstream will not be as negatively affected by increased flexibility as initially thought. It would be sad if we had to sacrifice local ecosystems as we try to combat global warming.”, Anton concludes.

Article: Burman et al (2020) [Case Study of Transient Dynamics in a Bypass Reach](https://www.mdpi.com/2073-4441/12/6/1585). DOI: 10.3390/w12061585