Case study:Built Kjøsnesbekken in the river Stjørdalselva

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Location: 63° 27' 36.50" N, 11° 11' 35.52" E
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Project overview

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Status Complete
Project web site
Themes Fisheries, Habitat and biodiversity, Hydropower, Hydromorphology, Monitoring
Country Norway
Main contact forename Arne
Main contact surname Jørgen and Kjøsnes
Main contact user ID User:Kasvio
Contact organisation NVE (Norwegian Water Resources and Energy Directorate)
Contact organisation web site http://www.nve.no/en/
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Kjøsnesbekken was built with gravel (photo: Arne Jørgen)

Project summary

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NVE constructed a complete new river side channel in an old river course next to the river Stjørdalselva in Norway. A unique collaboration between NVEs civil engineers, biologists and construction workers resulted in a 700m long and 2-5m wide miniature river containing all necessary habitats for salmonid fish.

It was built to compensate for the loss of suitable habitats in the main river due to human impacts such as railroad construction, hydropower regulation, removal of gravel from river bed, road building, flood protection work etc. Detailed planning with accurate calculations of slope, size of weirs, length of ponds, suitable water velocity on spawning grounds and use of correct substrate were done to ensure the new river could host fish of all cohorts.

Depth varies between 0,2 to 0,5m in the more rapid parts downstream the weirs. In the three resting ponds there are areas as deep as 1,5 m where fish can take shelter during periods of low water flows. Water flow varies between 150 – 800 l/sec depending on the flow in the main river. The inlet to the miniature river is through a 36 m long pipe with a diameter of 0,8m and the slope in the brook is 1:350m (3 ‰).

The use of riparian vegetation, roots with rootwad and large woody debris contributes with food and shelter for fish and also makes the area look very natural and untouched. The miniature river is constructed in a way that ensures that there will always be a minimum of running water. Discharge and water temperature is monitored in real-time. Along with annual biological inquires this will provide useful surveillance data that can be useful in similar projects.

Monitoring surveys and results

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Water flow and temperature is logged every hour Benthos and fish will be monitored yearly by NIVA. The first salmon fry was observed two days after the channel was opened. One month after there were fish in the whole side channel: A. salmon, brown trout and flounder. There were three cohorts of A. salmon observed: 1+, 2+ & 3+.

Lessons learnt

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Image gallery


Creek and main river (photo: Arne Jørgen)
Largest pond on the brook (photo: Arne Jørgen)
Added wood material (photo: arne Jørgen)
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Catchment and subcatchment



Site

Name Kjøsnesbekken in the river Stjørdalselva
WFD water body codes 124.666
WFD (national) typology
WFD water body name
Pre-project morphology Dry land, Old river bed
Reference morphology
Desired post project morphology
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest Brown trout (Salmo trutta), Atlantic salmon (Salmo salar)
Dominant hydrology
Dominant substrate Gravel, Bedrock, Clay
River corridor land use
Average bankfull channel width category 2 - 5 m
Average bankfull channel width (m)
Average bankfull channel depth category Less than 0.5 m
Average bankfull channel depth (m)
Mean discharge category 100 - 1000 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) 700700 m <br />0.7 km <br />70,000 cm <br />
Project started 2012/01/01
Works started
Works completed 2013/07/01
Project completed
Total cost category more than 10000 k€
Total cost (k€) 100100 k€ <br />100,000 € <br />
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 NIVA



Reasons for river restoration

Mitigation of a pressure Loss of suitable habitat and biodiversity
Hydromorphology
Biology fish, invertebrates
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

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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