Author(s): Mauro Carolli; Hakon Sundt; Sahra Sabil; Atle Harby; Jeffrey Tuthan; Jon Museth; Olle Calles; Markus P. Forst

Linked Author(s): Mauro Carolli, Håkon Sundt, Atle Harby, Markus Peter Först

Keywords: Barotrauma; Hydropower; Fish migration; Pressure dynamics; Turbine passage; Mitigation strategies

Abstract: Downstream migration of fish through hydropower facilities exposes them to rapid pressure changes which can cause injury or mortality. This study evaluates these risks using autonomous Barotrauma Detection System (BDS) sensors at four hydropower plants: Funnefoss and Kongsvinger in Norway, and Ätrafors and Lanforsen in Sweden. Sensors recorded nadir pressure and pressure rate of change under varying discharge and depth conditions, and results were compared to literature-based mortality thresholds for species such as European eel, Atlantic salmon, and European grayling. Findings indicate that pressure-related risks are generally low in these case studies, with nadir pressures and pressure change rates remaining above critical thresholds in most scenarios. Discharge influenced nadir pressure, while turbine type affected pressure dynamics. We also recorded potential blade strikes manually by looking at marks on the sensors. The study recommends further research on species-specific thresholds, strike events and migration patterns. Sensor-based monitoring offers a robust approach to improving fish survival and guiding fish -friendly hydropower operations.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.303

Year: 2026