Oral Presentation International Conference on River Connectivity (Fish Passage 2018)

Fish friendliness of archimedes screw turbines: quantified by forced fish passage (Albert channel, Belgium) (#150)

Ine Pauwels 1 , Raf Baeyens 1 , Ans Mouton 1 , Jenna Vergeynst 2 , Johan Coeck 1
  1. Research Institute for Nature and Forest, Brussels, VLAAMS-BRABANT, Belgium
  2. BIOMATH - Dept. of Mathematical Modelling, Statistics and Bioinformatics, Faculty of Bioscience Engineering, Ghent University, Ghent, Oost-Vlaanderen, Belgium

Hydro-power stations serve the essential need for power generation worldwide. However, they may seriously impact the aquatic ecosystem. Specifically fish that pass such structures may be killed or severely injured. Therefore scientists and engineers seek for high capacity pump and turbine types that minimize the physical impact on passing fish. For instance, turbines with Archimedes screws are assumed to be more fish friendly than widely used propeller type pumps and turbines. In the Albert Channel in Belgium, the first Archimedes screw hydropower plant was built, and more are to follow. The hydropower plant consists of three open Archimedes screws with a 10 m head and maximum capacity of 5 m³.s-1 each. In this study the impact of the Archimedes screws was assessed at three different modes of operation (3, 4 and 5 m³.s-1). To evaluate the impact, mortality and injury of 900 European eel (Anguilla anguilla), 900 roach (Rutilus rutilus), 900 bream (Abramis abramis) and 900 rainbow trout (Oncorhynchus mykiss) was quantified after forced passage. Injury was defined as 'heavily injured' (cuttings, bruises, bleeding, swelling or scale loss > 25%), 'slightly injured' (fin damage or scale loss < 25%) or 'not injured'. In general, around one third of the fish died and 10 % got injured due to turbine passage. Of the injured fish more than half were heavily injured. Nearly all dead or heavily injured fish showed bruises and some were decapitated. Furthermore, 10% of the individuals that survived the turbine passage, died within one week due to injuries. Although Archimedes screws are assumed to be fish friendly, this study indicates considerable fish mortality, mainly caused by fish being squeezed between the screw and its housing as indicated by the decapitations and bruises. Adaptations to the screws might further improve the fish friendliness of Archimedes screw hydropower plants.