Fischdurchgängigkeit mittels innovativer Buhnen in kombinierten skalierten und ethoyhdraulischen 1:1-Modellversuchen am Beispiel des Wienflusses

The Wien River is an artificial channel with a paved bed and uniform transverse profile over long stretches in the urban area of Vienna. Due to low water depths and high velocities at low flow fish migration is not possible in many places of the Wien River. In a scaled physical 1:8 model, an optimal groyne variant was developed by varying various groyne parameters, which can restore fish passability in the 4 km long project area downstream of the Kennedy Bridge. The final groyne design consists of alternately arranged deflecting groynes with a height of 0.2 m, a length of 4 m, an angle of 70 degrees and a groyne spacing of 6 m. The opportunities of the new BOKU River Lab were used to construct a part of the Wien River including the groynes on a 1:1 scale. Ethohydraulic tests were carried out to check whether the key fish species of the Wien River chub, gudgeon and loach can migrate through the groyne section at flow rates Q₃₃₀ and MQ. This was proven for the chub and the gudgeon. No nocturnal experiments were possible for the nocturnal and crepuscular loaches but they were able to stay in the groyne section without being drifted off. Near-natural 1:1 experiments in the BOKU River Lab make it possible to reproduce the full spectrum of small- and large-scale structures turbulent flows, in addition due to the use of Danube river water there are no water quality issues. Both aspects are decisive advantages for (etho-)hydraulic questions.