Case study:Deculverting Djupsund stream

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Location: 59° 7' 13.71" N, 10° 15' 42.78" E

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Project overview

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Status	In progress
Project web site
Themes	Habitat and biodiversity, Social benefits, Spatial planning
Country	Norway
Main contact forename	Miguel Angel
Main contact surname	Segarra Valls
Main contact user ID
Contact organisation	Vannområde Horten-Larvik
Contact organisation web site	http://https://www.vannportalen.no/vannregioner/vestfold-og-telemark/vannomrader/horten---larvik/
Partner organisations	Sandefjord Forvaltningsråd for Anadrom Laksefisk
Parent multi-site project
This is a parent project encompassing the following projects	No

Project picture

Project summary

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The Djupsund stream is a very small but very important stram for sea trout in the fjord Mefjorden (Sandefjord municipality), and it has been described as "a small sea trout machine". The upper part of the stream was culverted with pipes that were too small, and this caused problems for crossing way when strong rainfall episodes occurred. Around 80 m of the stream were daylighted, and a new 1 m diameter pipe was installed under the way in December 2020. Gravel was used to cover parts of daylighted stream and the bottom of the pipe under the crossing way.

We intend to restore the riparian vegetation along the daylighted stream during spring 2021, in cooperation with pupils from a nearby school.

Monitoring surveys and results

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The recolonization of the new stream stretch by sea trout will be monitored from 2021.

Lessons learnt

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New research shows that the ideal amount of spawning gravel in a stream is 20 % of the habitat (https://lakseelver.no/nb/news-2019/utlegg-av-gytegrus). We covered much more of the reopened stream, and will consider to take measures in order to increase the habitat variation.

Image gallery

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Djupsund stream after deculvering. Picture: Miguel A. Segarra Valls

Djupsund stream after deculvering. Picture: Miguel A. Segarra Valls

New pipe under way that crosses Djupsund stream. Picture by Miguel A. Segarra Valls

Sea tout at the opening of the old culvert in Djupsund stream (before restauration).Picture by Miguel A. Segarra Valls

Description restauration project in Djupsund Stream. Record: Norconsult

Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name Djupsundbekken WFD water body codes EU-ID:NO015-1467-R WFD (national) typology R110 WFD water body name Djupsundbekken 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 Dominant hydrology Dominant substrate River corridor land use Average bankfull channel width category Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started 2020/01/15 Works started 2021/02/15 Works completed Project completed Total cost category Total cost (k€) Benefit to cost ratio Funding sources Miljødirektoratet Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design 1.21.2 k€ <br />1,200 € <br /> Stakeholder engagement and communication Works and works supervision 99 k€ <br />9,000 € <br /> Post-project management and maintenance 33 k€ <br />3,000 € <br /> Monitoring 55 k€ <br />5,000 € <br /> Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Hydromorphology Continuity for organisms Biology Fish Physico-chemical Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Re-introducing spawning gravel Floodplain / River corridor Bigger diameter pipe under way Planform / Channel pattern Other Deculverting Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Description of the culverted stream, and initial technical proposals for deculverting (in Norwegian) SFFAL rapport dugnadsarbeid Djupsund.pdf Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information