Session B6: Design and Special Constructions of Fishway Pilot Sites on German Federal Waterways

Abstract: Current scientific knowledge does not cover all aspects of designing fishways on large German Federal Waterways. Therefore, the German Federal Institute of Hydrology (BfG) and the German Federal Waterways Engineering and Research Institute (BAW) together with the responsible German Water and Shipping Authority (WSV) address research questions in a R&D program, focusing on the link between hydraulics and fish behavior. The extensive R&D schedule includes the investigation of necessary auxiliary discharge, the optimum entrance location in the tail water and several other aspects of fishway entrance design (e. g. connection to river bed, design of shut-off devices) as well as the evaluation of different fishway types. The above questions are particularly important where fishways compete with hydro-power plants in terms of attraction flow and available discharge. They can only be addressed adequately by the in situ evaluation of hydraulic parameters and fish behavior. Therefore, six fishway pilot sites are planned at barrages with hydro-power on major Federal Waterways. Two aspects complicate the planning in particular: In order to investigate the effects of variable auxiliary discharge (from base flow up to 5 % of nominal discharge) large and varying amounts of water have to be added to the lowermost pools of the fishway. For these pools, special constructions are necessary to handle the amount of discharge while maintaining the passability for fish. Furthermore, the investigation of different entrance locations requires a sophisticated layout of the channels and pools which connect the entrances to the fishway. In order to pre-investigate details of the special constructions hydraulically, the BAW operates physical and numerical models. An overview of the research program at the pilot sites, the challenges in the planning process and the accompanying hydraulic models are subject of the presentation