Case study:Rehabilitation of the river Segeråga: Difference between revisions

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{{Case study status
{{Case study status}}
|Approval status=Draft
{{Location}}
}}
{{Project overview}}
{{Location
|Location=66.7167015, 13.2745597
}}
{{Project overview
|Status=In progress
|Themes=Fisheries, Habitat and biodiversity, Land use management - agriculture, Monitoring, Water quality
|Country=Norway
|Main contact forename=Kjetil
|Main contact surname=Hansen
|Contact organisation=Municipality of Rødøy
|Contact organisation url=www.rodoy.kommune.no/
|Multi-site=No
|Project picture=Graving 2 fangdam avsnitt G .JPG
|Project summary=Project background
 
Segeråga is located in Rødøy and Meløy municipality in the northern part of Norway. The river has been exposed to significant man-made changes during the last 30 years. New cultivation problems in the upper part of the river, with drainage and ditching of large peatlands, have had a documentable and significant negative ecological consequence for the river. The river has had increased sludge of fine particulate inorganic material (sludge/fine sand). The fish stock have probably been significantly reduces because of this.
 
The primary goal for the project is to increase the stocks of anadromous salmonids in Segeråga compared to the period 2013-2019.
A secondary goal is that the content of erosion and organic material in the water is reduced compared to the pre-situation, and that the river's quality as a habitat for fish and freshwater organisms is improved, especially through a reduction in the sludge of functional areas for trout and salmon.
 
Implementation
 
The project started with surveys in 2014, 2015 and 2016. Two reports describes the aquatic ecological status of segeråga, through benthic and juvenile fish surveys in the watercourse, supplemented with some water chemistry.
Based on this knowledge from the surveys, as well as field inspections and problemmapping, a rehabilitationplan was made in 2017. The rehabilitationplan suggests rehabilitation measures to re-establish the river as a river with sea-migrating salmonids, with particular emphasis on recovering the sea trout stock. This project was also a pilot project for this type of smaller rivers with man-made changes and new cultivation problems.
The rehabilitation started in 2017 includes measures as removing the inorganic material (sludge/fine sand), digging out ponds, gravel for spawning grounds, fish ladder, reduce runoff from agricultural land, habitat improvement, sediment ponds and reinforcement of riverbanks.
 
Summary/conclusion
 
The project successfully implemented all planned measures, with some locale adjustments in the field, such as the placement of spawning gravel. The last measures were implemented in 2020. Therefore, the results of the measures are not yet available. It will be important to monitor the river in a few years, to see the result from the measures and evaluate the project.
|Lessons learn=There has been no conflict with the landowners, and some have been involved in the measures.
 
The project has been possible due to a committed municipality and funding from the state.
|Project title=Rehabilitation of the river Segeråga
}}
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{{Case study subcatchment}}
{{Case study subcatchment}}
{{Site
{{Site}}
|Name=Segeråga
{{Project background}}
|WFD water body code=159-194-R
{{Motivations}}
|WFD (national) typology=RMM1221
{{Measures}}
|WFD water body name=Segeråga
|Pre-project morphology=shallower, overgrown
|Desired post project morphology=Run-glide, Ponded, Pool-riffle,
|Heavily modified water body=No
|Protected species present=No
|Invasive species present=No
|Species=Atlantic salmon (Salmo salar), Sea trout (Salmo trutta), arctic charr (Salvelinus alpinus),
|Dominant hydrology=Perennial Snow-rain (SR)
|Dominant substrate=Silt
|River corridor land use=Intensive agriculture (arable), Coniferous woodland (semi natural),
}}
{{Project background
|Reach length directly affected=10000
|Project started=2014/07/01
|Works started=2017/06/01
|Total cost category=100 - 500 k€
|Total1 cost=206
|Funding sources=Norwegian Environment Agency, County Governor og Nordland
|Investigation and design cost category=10 - 50 k€
|Invst and design cost=36
|Investigation and design Lead organisation=Rødøy municipality
|Works1 and supervision cost category=100 - 500 k€
|Wrk and supervision cost=170
|Works and supervision Lead organisation=Rødøy municipality
}}
{{Motivations
|Specific mitigation=Land drainage,
|Hydromorphological quality elements=Channel pattern/planform, Continuity of sediment transport, Flow velocities, Structure & condition of riparian/lake shore zones, Substrate conditions, Width & depth variation,
|Biological quality elements=Fish: Abundance, Fish: Age structure, Invertebrates: Diversity,
|Physico-chemical quality elements=Nutrient concentrations,
|Other motivation=Bank erosion,
}}
{{Measures
|Bank and bed modifications measure=Construction gravel bays, gravel for spawning grounds, Removal of sediment, Removal of fish barriers, Natural erosion embankments, er
|Floodplain / River corridor=Removal of sediments,
|Planform / Channel pattern=Decrease sedimentation, Creation of pond,
|Other technical measure=Fish habitat restoration, Improving fish migration, sediment ponds
|Management interventions=Reducing bank side collapse (source of sediment),
}}
{{Hydromorphological quality elements header}}
{{Hydromorphological quality elements header}}
{{Hydromorphological quality element table row
{{Hydromorphological quality element table row

Revision as of 13:59, 2 November 2020

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Image gallery


Removing inorganic material (sludge/fine sand. Photo: Kjetil Hansen, Rødøy municipality
After removal of the inorganic material (sludge/fine sand), reinfoorcement of river bank and gravel for spawning grounds. Photo: Kristin B. Klausen, local watercoordinator.
Excavation of sediment ponds in the upper part of the river. Photo: Kjetil Hansen, Rødøy municipality
Sediment pond. Photo: Kjetil Hansen, Rødøy municipality
File:Sediment pond in the middel part.jpg
Excavation of sediment ponds in the middle part of the river. Photo: Kjetil Hansen, Rødøy municipality
File:Sediment pond in the middel part after measure.jpg
Sediment ponds in the middle part of the river after measure. Photo: Kristin B. Klausen, local watercoordinator.
Construction of fishing ladder. Photo: Kjetil Hansen, Rødøy municipality
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Catchment and subcatchment



Site

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Reasons for river restoration

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Measures

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Floodplain / River corridor
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Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Substrate conditions Yes No Yes No No Awaiting results
Width & depth variation Yes No Yes No No Awaiting results

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish: Abundance Yes No No Yes No Awaiting results
Fish: Age structure Yes No No Yes No Awaiting results
Invertebrates: Diversity Yes No No Yes No Awaiting results
Invertebrates: Abundance Yes No No Yes No Awaiting results

Physico-chemical quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Nutrient concentrations Yes No No Yes No Awaiting results
PH Yes No No Yes No Awaiting results

Any other monitoring, e.g. social, economic

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


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Additional links and references

Link Description
http://https://brage.nina.no/nina-xmlui/handle/11250/2446580 Plan for rehabilitation of the river
http://https://brage.nina.no/nina-xmlui/handle/11250/2436896 Fish biological survey
http://https://niva.brage.unit.no/niva-xmlui/handle/11250/2478427 Survey of physico-chemical quality elements and biology

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