Balık geçidi tasarım değerlendirmesi: Vereinigte Weißeritz nehri örnek çalışması

The fish passage issue is an essential element in the environmental impact assessment of small hydropower projects. These projects not only create a barrier for upstream movement, but they can also induce mortality to fish population by passage through turbines. Downstream fish passage at hydropower stations is a relatively recent issue, and devices to safely transit fish downstream of turbines are still under development. Most of the devices that were installed were on existing generating stations, and so, owners usually did not have much flexibility in the type of device that was installed. Three types of devices are usually found at hydroelectric sites, bypass channels, physical barriers (i.e. screens), and physiological barriers (louvers, lights, sound, etc.). The efficiency for downstream migration devices varies according to site configuration and species present. Even though high efficiencies were found for certain salmonids such as Atlantic salmon, no single device has attained 100% efficiency. The use of certain devices such as fine mesh screens has direct impact on generating station operation because of high maintenance needs, and headloss through the screens which lowers power production. Upstream fish passage is as the most investigated type of fishways that are in place have been so for a long time. Consequently, these systems are well standardised and many authors have presented guidelines for their design. The most common fishway is the pool and weir which is found in many countries around the world. Finally, the monitoring of fish passages at hydropower sites should be an integral part of the project. This activity is frequently left aside, but needs to be carried out to evaluate the efficiency of systems that are built for fish passage. Mark-recapture techniques or telemetry are tools that can be used for such a purpose. In this thesis, the fish passage nearby WKA Bienertmühle weir was investigated onsite and novel fish passage design is proposed. Fish passage instructions, fish passage design principles, background of the case study area: geography, population and socio-economy, topography, meteorology, hydrology, river properties: ecohydrology, hydromorphology, hydrobiology, hydrochemistry, ecohydraulics, materials and methods: status quo of Vereinigte Weißeritz River, fish passage location and design, methods of approach: conventional and ecohydraulics, evaluations and discussions: practical solutions: optimum fish passage concept: legislation, proposed design: operation criteria and novel fish passage design are given respectively. The existing fish passage is one vertical slot type of fish passage and a small hydro power plant is located nearby WKA Bienertmühle weir. Small hydropower project development has been, for the last decade, one of the sectors in the energy field that has been very active. Where the preceding decades saw a fair number of large hydroelectric developments, the last decade was almost exclusively made up of smaller projects that were essentially developed by private producers. One of the main environmental challenges of small hydropower development is related to fish passage both upstream and downstream. These migrations are ecological imperatives for populations of anadromous fish. Entire populations of these migratory species can be eliminated if either up or downstream migrations are blocked. Small scale hydro developments are often an impediment to these migrations. Efficient fish passage is required under many jurisdictions in order for regulating agencies to approve hydropower projects, whether they be new developments or under relicensing. Hydroelectric dams can also cause other impacts apart from blocking fish migrations. For instance, dams can have effects on water temperature, flow regimes, dissolved gas content, species diversity, and other ecological parameters that may have direct or indirect effects on fish. Additionally, climate change alters the fish assemblage structure and function distribution in Europe. For this reason, a relatively new field called ecohydraulics that is a subdiscipline of hydraulics that deals with fish passage facilities is proposed. This field constitues links between biological (swimming performance, behavioural responses of fish) and physical (hydraulic, hydrologic) features of aquatic systems. The result of this thesis showed that the fish passage nearby WKA Bienertmühle weir was found to be not functional. Therefore, a novel fish passage design that is comprised of two fish passage facilities (serves both upstream and downstream migration) and operational system was proposed. This novel design is retrofitted design of the existing fish passage with new design for downstream fish migration.