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Innsbruck, Austria

Schoberl F.,University of Innsbruck | Zeiringer B.,University of Vienna | Moritz C.,ARGE Limnologie GesmbH
Osterreichische Wasser- und Abfallwirtschaft | Year: 2014

The EU Water Framework Directive commits member states to achieve good ecological status in all waterbodies. Artificial or heavily modified waterbodies must reach at least its good ecological potential. In view of these requirements, simple and feasible methods are required in order to evaluate habitat suitability for relevant target species in larger river reaches. Well-developed models for determining the relationship between stream flows and habitat for target species mainly based on micro- and meso-scale already exist. However, the application of such models is complex and time-consuming and consequently limited to relatively short river segments. The objective of this study is to develop a simplified applicable assessment model to evaluate habitat conditions for selected target fish. This model uses hydro-morphological indicators for the habitat assessment and relies on correlative relations between habitat suitability and hydro-morphological features of river stretches (average Froude-number, relative flow width, mean bed slope, relative water depth and flow velocity). The indicators were determined as reach-related averages, derived from 2D model simulations (hydraulic and habitat-specific). Particular emphasis was laid on using a wide range of river stretches with different hydro-morphological characteristics (hydrology, bed substratum, bed structures, degree of braiding, sinuosity of the river course, mean bed width and bed slope). As a result, a set of model equations enables the evaluation of fish habitat conditions in river stretches as a function of flow and morphology. The habitat suitability assessment focuses on four preselected target species: brown trout, European grayling and for low slope rivers common nase and barbel. © 2014 Springer-Verlag Wien.

Schletterer M.,TIWAG Tiroler Wasserkraft AG | Senn G.,TIWAG Tiroler Wasserkraft AG | Menghin M.,TIWAG Tiroler Wasserkraft AG | Hubmann M.,ARGE Limnologie GesmbH | And 4 more authors.
WasserWirtschaft | Year: 2015

Construction work of the fish pass in Wenns was started in late 2013 and the project was successfully completed soon after in April 2014. The 140 m long structure is a combination of a near-natural bypass channel and a special vertical slot pass so that fish (mainly brown trout) can safely bypass the weir. In addition, a residual flow facility ensures a minimum flow of 600 l/s. TIWAG is the first company in Austria to install an innovative system to monitor the functionality of the fish pass at Wenns. The Riverwatcher fish counter supplied by Icelandic company VAKI is a fish-friendly alternative to fish traps and electrofishing equipment. The system has already proven its worth in many European: watercourses with a great diversity of species.

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