ARGE Limnologie GesmbH

Innsbruck, Austria

ARGE Limnologie GesmbH

Innsbruck, Austria
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Schletterer M.,TIWAG TirolerWasserkraft AG | Hofer B.,TIWAG TirolerWasserkraft AG | Obendorfer R.,TIWAG TirolerWasserkraft AG | Hammer A.,TIWAG TirolerWasserkraft AG | And 10 more authors.
River Sedimentation - Proceedings of the 13th International Symposium on River Sedimentation, ISRS 2016 | Year: 2017

Sedimentation and the management of hydropower reservoirs is one of the big global issues concerning future hydropower use. Exemplarily for Asia a reduction of 80 % of the potential storage volume is predicted by 2035. For Europe those thresholds in sedimentation are predicted by 2080. Related consequences – beside a reduction of the storage volume and the restriction in hydropower production – are effects on aquatic ecology linked to artificial flushing of deposited fines. Impacts on aquatic ecology, however, can be manifold, especially in a change in habitat quality with possible clogging of the gravel matrix and an increase of stress due to an increased turbidity. The presented case study is dealing with a lowering of the water surface level of the reservoir Gepatsch (Tyrol) beyond the operational level. This was a controlled drawdown of the reservoir, which has to be distinguishes from reservoir flushing. However, also from the controlled drawdown an increased load of suspended sediments was expected. Based on the awareness of possible negative ecological consequences a complex set of measures and an integrative monitoring design was been developed. Monitoring is based on detailed event based quantification of eroded sediments. High resolution turbidity data are available for the entire Inn river in Tyrol. Moreover, we analysed the biological quality elements macrozoobenthos and fish at selected stretches. In addition, freeze-core samples were taken before and after the lowering of the reservoir volume, in combination with cocooning of brown trout during the spawning period. This case study brought up an extensive data set, however for future monitoring activities in similar projects we suggest to concentrate on a limited number of monitoring sites, including a reference station as well as a station to assess the emission. Downstream effects could be assessed numerically, but it has to be considered that additional stations provide the possibility for a detailed process study, i.e. the analyses of processes that are causing a natural increase of suspended sediments. © 2017 Taylor & Francis Group, London.


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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