This thesis deals with types of fishways and reasons for building them. It focuses on the
fishway at HPP Arto Blanca, the possibilities for its optimization and the analysis of the
ichthyological review based on the hydraulic data found in the fishway.
Fishways are built in order to prevent interruptions of a watercourse which may occur when
an obstacle is constructed. Especially migratory species of fish, but also some other
organisms that depend on different habitats for their long-term survival, can be affected by
The problem of fish migration in the lower section of the Sava River in Slovenia is presented.
Species of fish living there and their swimming abilities are also described.
This is followed by the description of the most frequently used types of fish passes. Certain
types of fish passes are suitable only for certain types of fish and specific types of obstacles.
The fishway at HPP Arto Blanca was built in 2009 and is one of the few well-functioning
fishways on large dams in Slovenia. Its structure and the operation mode of its inlet section
The optimization of the fishway is then analyzed using the program PCFLOW2D and the k-ε
turbulence model for unsteady flow. The geometry of a part of the inlet section of the existing
fish pass at HPP Arto Blanca (implemented as a swimming pool type with vertical slots)
served as a basic geometry. It was determined that, by moving the slots between the pools
toward the center section, the maximum speed and areas with markedly high dissipation of
turbulent kinetic energy ε are reduced. Consequently, areas with markedly low values of
velocity and ε decrease. It was also found that a change in discharge causes no major
parameter changes in the fishway with vertical slots. The only change observed is in the
Finally, an evaluation was performed, comparing the results of the ichthyological review of
the fishway at HPP Arto Blanca with the results of the optimized hydraulic values in the
fishway. The existing fishway was found to be well functioning.