In this research project, power plant-related damage to fish is assessed at new innovative hydropower plants and at conventional hydropower plants with newly installed fish protection facilities in ten Bavarian rivers. The assessed innovative technologies include power plants with VLH turbines, Archimedes screw turbines, movable hydroelectric power plants and shaft power plants. At conventional power plants, the effects of horizontal and vertical bar screens as well as fish bypass systems such as vertical slot passes, spillways and deep channel bypasses are evaluated. In addition to the assessment of fish damage, the weir or power plant induced serial discontinuity, considering the change of habitat quality and aquatic communities (fishes, macroinvertebrates, macrophytes and algae), is quantified. The results of this study can assist authorities and engineers to improve techniques as well as operation management, and to find ecologically sustainable solutions for future hydropower use.

Fish damage

To record fish migration and the intensity of fish injuries caused by different types of hydropower plants and the fish protection facilities, fyke nets were placed downstream from the turbines, spillways and fish passes. The number of migrating fishes and the severity of their injuries were categorized recorded on a specifically designed datasheet. Delayed mortality of captured fish was monitored over a 72 hour period. To improve the fishfriendlyness of hydropower facilities knowledge on fish behaviour in spatial proximity of the turbine and screen is essential. For this purpose an ARIS (Soundmetrics, USA) imaging sonar was used .

Fish ecological monitoring – at the HPP Baiersdorf/Wellerstadt TUM members are hauling the nets to collect the fish and put them into the caging tanks, where the fish are observed and HPP-induced damages can be identified (Photo: Andreas Heddergott TUM)
 

Habitat quality

Besides the negative effects on fish migration and health, hydropower generation leads to severe changes of habitat integrity in rivers. To quantify the effects of habitat fragmentation and degradation, habitat surveys were conducted at upstream and downstream sides in spatial proximity of the weirs. This included the seasonal assessment of the fish community, macroinvertebrates and benthic algae, substratum composition, flow velocity and physicochemical parameters (temperature, specific conductance, dissolved oxygen, redox potential and pH). Furthermore a Side-Scan-Sonar (Humminbird,USA) was used to detect changes in the spatial distribution of key habitats such as dead wood accumulations, boulders, gravel banks and macrophytes.

Fish ecological monitoring – at the HPP Baiersdorf/Wellerstadt nets are placed downstream the turbine to investigate the HPP induced injuries for fish (Photo: Andreas Heddergott TUM)

 

For further information please visit the webpage: https://www.energieatlas.bayern.de/thema_wasser/umweltaspekte/monitoring.html

 

Diana Genius (Bayerisches Landesamt für Umwelt)