Case study:Rheinfelden bypass

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Location: 47° 34' 11.70" N, 7° 48' 35.20" E
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Project overview

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Status Complete
Project web site
Themes Economic aspects, Fisheries, Habitat and biodiversity, Hydropower, Hydromorphology
Country Switzerland
Main contact forename Walter
Main contact surname Binder
Main contact user ID User:Kasvio
Contact organisation
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
The largest bypass for fish in Europe. The bypass is constructed as nature-like (photo by Pinja Kasvio)

Project summary

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The bypassing water course at the hydropower plant Rheinfelden, on the High Rhine, is the largest fish pass facilitiy of this type in Central Europe. The old hydropower station was a diversion-channel type plant. The new station is a run-of-river power plant. Three fishways are installed, a vertical slot pass at the power house (left bank), the new bypassing river course installed in the old headrace channel(right bank) and a rock cascade pass which connect the tailwater of the weir with the river course.

The main intention of this new river course is to provide suitable habitat for rheophilic species, especially spawning grounds for gravel dependent fish species, for example barbel (Barbus barbus) and nase(Chondrostoma nasus).

With a width of 40-50 m, a mean gradient of 0.9 % and a discharge of up to 35 m³s-1 the bypass channel has the character of a mountain river. The mean discharge is 16 m3/s and the attraction flow is 15 m3/s.

The aim is to provide a high variety of bottom and flow structures induced by sequences of riffles, bars, pools and single gravel islands. The bed material consists of continuous gravel. In riffles and fast flowing reaches coarser material is provided. A deeper flow path ensures fish passage even at minor discharges. The river banks are characterized by bars, shallow regions, small bays, undercut banks and riparian vegetation. The bypass channel is connected to the weir impoundment with a gentle transition involving several braided channels. The intake structure itself is divided into two sections. One section will be controlled by two gates, the other will be unregulated. The unregulated section will guarantee a constant discharge of 10 m³s-1 in the bypass channel. Additional discharge up to 25 m³s-1 can be provided via the regulated gates in order to provide a dynamic flow regime.

The downstream entrance is designed as a rock ramp with a steeper gradient (3 %), thus downstream water-level fluctuations are limited to this ramp; i.e. flow characteristics in potential spawning grounds in the bypass channel will not change. The cross-section at the mouth of the channel is narrowed to provide more efficient attraction flow into the tailrace.

The total cost of the project was 6 milj. € and the by-pass channel cost 4 milj. €. There is no constant monitoring yet, but they have calculated the amount of the fish in the by-pass channel to be 30 000. In the other fish way the number of fish was 3 000.

Monitoring surveys and results

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Lessons learnt

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Image gallery


The map of Rheinfelden bypass. New power plant designed as run-of-river type. Near-nature water course installed in the old headrace channel. (photo: Walter Binder)
Fish counter at the end of Rheinfelden bypass (photo: Pinja Kasvio)
Hydropowerplant (photo Pinja Kasvio)
Pool fish pass (photo: Pinja Kasvio)
Technical fish pass (photo Pinja Kasvio)
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Catchment and subcatchment



Site

Name
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology
Reference morphology
Desired post project morphology
Heavily modified water body No
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest Barbel (Barbus barbus), nase (Chondrostoma nasus)
Dominant hydrology Artificially regulated, Environmental flow
Dominant substrate Gravel
River corridor land use Urban, Coniferous woodland (semi natural)
Average bankfull channel width category 10 - 50 m
Average bankfull channel width (m) 40-50"-50" is not declared as a valid unit of measurement for this property.
Average bankfull channel depth category
Average bankfull channel depth (m)
Mean discharge category 10 - 100 m³/s
Mean annual discharge (m3/s)
Average channel gradient category 0.01 - 0.1
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started
Works started
Works completed
Project completed
Total cost category
Total cost (k€) 10 milj €"milj€" is not declared as a valid unit of measurement for this property.
Benefit to cost ratio
Funding sources

Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
Investigation and design
Stakeholder engagement and communication
Works and works supervision
Post-project management and maintenance
Monitoring



Reasons for river restoration

Mitigation of a pressure
Hydromorphology
Biology
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
Social measures (incl. engagement)
Other


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish: Abundance No No Yes Yes No

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Any other monitoring, e.g. social, economic

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative


Monitoring documents



Additional documents and videos


Additional links and references

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Supplementary Information

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