Case study:Wettingen, nature-like fish pass

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Location: 47° 27' 24.77" N, 8° 19' 16.26" E

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Project overview

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Status	Complete
Project web site
Themes	Economic aspects, Fisheries, Hydropower
Country	Switzerland
Main contact forename	Walter
Main contact surname	Binder
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Parent multi-site project
This is a parent project encompassing the following projects	No

The nature-like bypass channels middle part has a rock-cascade pass. (photo by Pinja Kasvio)

Project summary

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In Wettingen there is a great example of a small nature-like bypass channel at the weir Wettingen on the Limmat downstream from Zurich which surmounts the very big height of 18.30 m. Nature-like bypass channels total length is 620 m, discharge 0.4 m³/s and additional attraction water is 0.6 m³/s. Total difference in water level is 18.30 m with high mean slope 3 %.The lower section consists of a technical fish. Whereas a near-nature water course was formed in the upper section, a rocky-cascade fishway with a height of 10 meters surmounts the biggest part of the altitude. Due to the limited space the lower section consists of a vertical-slot-pass which is converted into a collection-gallery at the power house. Leading back the water course to the power house is not possiblewhen it comes to bigger bypass channels. Splitting the water into two branches offers a good solution for this small channel. The main branch continues towards the tailwater as a near-nature water course and ends further downstream, where a connection to the natural river bed is possible. The smaller second branch diverts from the main branch towards the power house and is formed as a vertical slot-pass.

The nature-like bypass channel has a trail on its side, so the residents can enjoy the lovely scenery and see some trouts when passing by.

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Site

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Pre-project morphology
Reference morphology	Bedrock cascade, Artificial channel
Desired post project morphology
Heavily modified water body	No
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Protected species present	No
Invasive species present	No
Species of interest
Dominant hydrology	Artificially regulated
Dominant substrate	Bedrock, Gravel
River corridor land use	Urban, Broadleaf/mixed plantation
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Project background

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