Ökologische Optimierung des Fischabstiegs durch die Turbine

A major challenge for ecological compatible hydropower usage remains fish downstream migration. The main problem are the injury and mortality rates of the fish when they pass through the turbines. Common solutions require high efforts for screening and bypass systems, specialized turbines or restricted operating schemes. The so-called IDA-technique provides an alternative approach to reduce fish mortality in turbines in order to achieve required protection levels for fish populations. The actual fish damage rates depend on passage details which are determined by the fish behaviour. Therefore, a targeted manipulation of the fish behaviour can minimize the impairment during turbine passage. A favourable implementation of the IDA-technique is based on electric fields and the particular electro-sensitivity of fish. Electrodes upstream the turbine intake can influence the relevant passage attributes of the fish. A series of competitive tests at a small-scale Kaplan turbine test setup yielded a reduction of fish mortality of more than 50%. The technique can be of special interest for an efficient retrofitting at existing hydropower facilities. It can also be combined with conventional fish protection techniques for further optimization of ecological performance.