We are saving fish in hydropower rivers from "the bends"

The project leader of the EU Horizon project iamp-Hydro is Sebastian F. Stranzl from NORCE LFI – the Laboratory for Freshwater Ecology and Inland Fisheries.

"We are developing new technology to provide real-time information on gas supersaturation in the water around hydropower plants, preventing harm or death to fish and bottom-dwelling organisms. In addition to the newly developed TDG probes, the loggers can be equipped with oxygen and pH probes," explains Stranzl.

The task in iamp-HYDRO: Reliable monitoring of key physical parameters related to hydropower regulation (temperature, water level, gas supersaturation, pH, and oxygen).

NORCE is leading Work Package 4 (Ecology Monitoring Sensor Development) and Work Package 5 (Ecology Data Analysis). We have secured funding to develop a probe capable of detecting conditions that may harm fish in real time, triggering alerts to adjust hydropower operations accordingly.

The EU project focuses on:

Hydropower will play a crucial role in the energy world of the future—an energy sector undergoing a fundamental transformation with the rise of digitalisation. As a result, power systems are being more thoroughly monitored, and artificial intelligence (AI) and big data are increasingly integrated into daily operations.

However, today’s hydropower plants in the EU are ageing. It is estimated that 50% of them will require modernisation before 2030. In particular, digitalisation-related upgrades are urgently needed in the short and medium term to provide enhanced services, increase grid flexibility, improve environmental and socio-economic sustainability, and support Europe’s green and digital transition.

This is where our sensors come in—to ensure that hydropower plants cause as little environmental harm as possible. The five pilot sites in Spain and Greece are the first to benefit from NORCE’s technological innovation.

Sebastian and his team are NORCE colleagues Rowan Hamper, Bård Henriksen and Gro Fonnes. Fonnes and Henriksen work in the technology department at our institute and are key players in helping Sebastian deliver on his promises.

"We wanted a digital, pre-calibrated probe that could be connected to a logger or storage unit and communicate directly with the hydropower plant in real time while simultaneously sending data to the cloud," says Sebastian F. Stranzl.

And that’s exactly what he got—fully developed and perfectly functioning in-house at NORCE, thanks to his technology colleagues from the research groups Autonomous Systems and IoT and Digital Systems. In the lab, the research team goes through a range of newly developed probes, sensors, and data packages designed to be deployed around hydropower plants.

Gas Supersaturation or "The Bends"

You’ve probably never considered the idea of fish suffering from "the bends," but that’s exactly what this is about.

"The tolerance levels for gas bubbles in water vary from species to species," explains Rowan Hamper.

"Gas supersaturation occurs when air dissolves under pressure in water. When the water returns to atmospheric pressure—meaning when the bubbles rise to the surface—this can be harmful to fish and bottom-dwelling organisms."

This is a well-known phenomenon in human diving as well. Most of us have heard of decompression sickness (the bends), which happens when a diver ascends too quickly after a deep dive, causing bubbles to form in the blood—potentially leading to severe illness or even death.

"Yes, it can definitely be compared to the bends," confirms Rowan Hamper.

The ultimate goal is to provide highly stable and accurate monitoring and develop a model that can predict hazardous conditions—helping to make hydropower production more environmentally friendly.

The new sensors have been developed under the leadership of Bård Henriksen, drawing on years of experience in designing detection tools for water, air, and land-based applications.

These are robust and versatile digital sensors designed for monitoring water levels, gas supersaturation, and water temperature. They can detect and report key environmental parameters in rivers, such as gas supersaturation and deviations in flow or temperature.

"In addition, these smart sensors communicate directly with the hydropower plant’s operations manager. This allows the plant owner to adjust water flow in real time, ensuring an environmentally friendly water supply that prevents harm to fish," says Henriksen. He adds: "The system is also designed to accommodate additional sensors required by the industry, making the platform highly adaptable."

Upgrading existing analogue gas supersaturation meters to digital sensors results in lower power consumption, improved accuracy, and more reliable data transmission.

Deployment in Spain and Greece

In February, Rowan Hamper oversaw the full deployment of the system in Spain and Greece. After successfully installing the probes in the rivers and connecting the data loggers to the hydropower plants, local data collection at the EU pilot sites is now underway.

"Now, we can finally start reviewing the data on our computers back home," says Gro Fonnes.

Fonnes is responsible for data analysis and the software suite that accompanies the monitoring system. This software enables real-time readings of river and hydropower-related water data. Her expertise is crucial in integrating the sensors and ensuring seamless data transmission. The data is sent either via LTE-M data loggers using 4G or, in areas without 4G coverage, via a cloud service managed by NORCE. This ensures real-time access and use of the collected data.