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Breitenfurt bei Wien, Austria

Gehrer A.,Andritz AG | Skouteropoulou I.,Andritz AG | Kellner R.,VERBUND Hydro Power GmbH

In order to refurbish and upgrade the VERBUND-hydropower plant Ybbs-Persenbeug, six large Kaplan turbines were subject to modernization. A metamodel-assisted evolutionary algorithm (MAEA) coupled with an inviscid flow solver (3D Euler) was applied to design-optimization and full 3D-Navier-Stokes simulations (CFD) were performed. Finally, model test results that confirmed the performance of the new runners are presented including comparisons between experimental data and CFD-results. Source

Trauner D.,University of Vienna | Funk A.,University of Vienna | Polz E.-M.,University of Vienna | Feldbacher E.,University of Vienna | And 3 more authors.
Osterreichische Wasser- und Abfallwirtschaft

Floodplains and wetlands are among the most endangered ecosystems worldwide. River-regulation and flood protection measures cut off these formerly highly dynamic systems from their natural water level fluctuations and water exchange conditions leading to siltation processes. Restoration measures to counteract these developments need to be assessed for the effect on currently established habitats and communities in order to estimate their effects, as species with different habitat preferences and different protection status do react distinctly different. This article will present how habitat modelling was used in a case study of the Untere Lobau to assess and predict the effects of potential management measures. The Untere Lobau is a wetland ecosystem of the Danube east of Vienna. It is part of the national park Donau-Auen and a protected area according to the EU habitat-directive. Prior to the river regulation, at the end of the 19th century, the Untere Lobau was a dynamic floodplain. Today, siltation processes endanger especially the status of the aquatic habitats. Three management options were investigated: 1) business as usual – No implementation of additional hydrological measures, thus siltation processes are not mitigated; 2) a water enhancement scheme – A small amount of water is supplied to preserve the water bodies at the current status quo; 3) partly reconnection – An upstream reconnection of the floodplain to the main channel of the Danube, leading to a more rheophilic characteristic of the system moving towards conditions prior regulation. Based on a model approach and calculating habitat preferences via binary logistic regressions of selected species from different organism groups, an increase or decrease of available suitable habitat area (weighted usable areas) could be estimated. This study proofed clearly that models can assess the effects of hydrological management measures on the biocenosis and that they are a valuable tool for supporting the decision taking process in wetland management. © 2016 The Author(s) Source

Klasz G.,Ingenieurburo Klasz | Gabriel H.,DonauConsult Ingenieurburo GmbH | Habersack H.,University of Vienna | Schmalfuss R.,VERBUND Hydro Power GmbH | And 2 more authors.
Osterreichische Wasser- und Abfallwirtschaft

The Danube east of Vienna was originally an untamed, widely branching river with an approximately stable bed elevation. Regulation in the second half of the 19th century changed its morphology fundamentally—initially through upstream regulation and the consequent bedload deposit resulting in heavy aggradation—and subsequently left the bed elevation and water level almost the same until around the 1940s. Only in the second half of the 20th century did the bed elevation and low and mean water levels decrease significantly, and this trend—amplified by the power plant extension—continues today, despite constant bedload dumps to ensure the tailwater supply for the power plant at Vienna Freudenau. Further east from the Austrian-Slovak stretch of border, congestion due to the Gabčíkovo power plant becomes apparent: most of the bedload is again deposited here. This study investigates these processes using hydrographic observations in their spatial and temporal context, and, based on actual bed elevation measurements, creates a bedload balance and compares it with the results of previous studies. Bed erosion in the Danube floodplains and the local national park has far-reaching consequences, especially through siltation and scrub encroachment in the river’s branches, which are further amplified by flat, fine sediment deposits in the foothills and the formation of embankments. In the long term, flood and other water management objectives will also be adversely affected. © 2016, Springer-Verlag Wien. Source

Harb G.,University of Graz | Badura H.,VERBUND Hydro Power GmbH | Schneider J.,University of Graz | Zenz G.,University of Graz
Osterreichische Wasser- und Abfallwirtschaft

Sedimentation processes caused by reductions in flow velocity in reservoirs have undesired effects, not only in the reservoir area itself but also downstream. In addition to possible flood protection problems at the head of the reservoir due to raising of the bed levels, sediment depositions near the weir can affect the operation of the hydro power plant. Downstream siltation, a lack of coarse mobile sediment and problems with reservoir flushing (e.g. too high a sediment concentration) are direct consequences of this problem. This article thus deals with the example of the optimization of the flushing operation for the Loeben power plant, which is characterized by its small size. At the head of the reservoir coarse sediments are deposited, which increases the flood risk in the area. During the first years of service, it became clear that flushing was necessary to limit the sediment depositions in the reservoir. Field measurements as well as numerical simulations were performed to achieve optimal reservoir management. The present example shows that the adapted flushing operation strategy improved the sediment management in the reservoir. © 2015, Springer-Verlag Wien. Source

Harreiter H.,VERBUND Hydro Power GmbH | Frik G.,VERBUND Hydro Power GmbH | Schmalfuss R.,VERBUND Hydro Power GmbH | Reckendorfer W.,VERBUND Hydro Power GmbH

The implementation of the EU Water Framework Directive and the National Water Management Plan (NGP) is a major challenge on large rivers. The previous projects on the Austrian Danube show that the requirements formulated in the EU-WFD cannot be achieved by measures to improve fish passage alone. In order to achieve the objectives the improvement of habitat conditions is required. One of the key habitat types are permanently connected side arms, which provide spawning grounds and shelter from ship-induced waves. A stepwise procedure using different types of funding has proven successful so far to implement the environmentally and economically feasible in a reasonable time frame. It is also important to co-ordinate all actions with the different types of usage of the Danube (energy, navigation, flood protection⋯) and the responsible stake holders. This successful approach will also be taken in the future. The strategy of VERBUND regarding the requirements of the EU-WFD and the NGP is a systematic approach which prioritizes the creation and connection of habitats before the implementation of pure fish passage. Source

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