Biologische Wirksamkeit von Leitrechen-Bypass-Systemen - Aktueller Kenntnisstand

For protecting fish at their downstream passage of European hydropower plants, operators increasingly use the angled bar rack bypass system of Ebel, Gluch & Kehl. Detailed biological functional data of the system are now available for a variety of sites. The paper provides an overview of the essential findings while also taking into account studies on similar systems where the flow approaches the horizontal bar rack from an acute angle. On the basis of these data and operational experience, the paper derives and renders practical advice on the future application of angled bar rack bypass systems. The general conclusions presented in the paper can be summarized as follows: (1) angled bar rack bypass systems induce beneficial behavioural effects and considerably reduce turbine-related fish mortality. (2) For eel (Anguilla anguilla) and salmon (Salmo salar), both diadromous species, 80 to 100 % efficiency is achievable. (3) When planning angled bar rack bypass systems, the established rules for position, dimension and design need to be applied.