Case study:Restorations of Ritobäcken brook

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Location: 60° 19' 5", 25° 12' 16"
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Project overview

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Status Complete
Project web site
Themes Habitat and biodiversity
Country Finland
Main contact forename Jukka
Main contact surname Jormola
Main contact user ID
Contact organisation SYKE
Contact organisation web site http://www.environment.fi
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
projects
No
Rirobacken brook after restauration_summer 2011 (photo: Airi Kulmala)

Project summary

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Ritobäcken brook is a small tributary of River Sipoonjoki which is located near to Helsinki partly in a Sipoonkorpi National Park. Brook serves as a drainage channel for the surrounding agricultural fields which constitute 13% of the 10 km2 catchment area. The brook is also a reproduction area for the vulnerable sea run brown trout (Salmo trutta) of the Baltic Sea. Brook has been restored twice. First time was 2006 when 230 meters of dredged and straightened brook was restored as the aim of improving the habitat for the existing brown trout stock. The object was to support the natural development of the brook by adding sinousity, width and depth variation. Also stones and gravel were added and replaced to create habitats for the brown trout. In 2010 brook was restored as the aim of maintaining and enhancing the habitat diversity of the brook for migratory fish while decreasing flooding of the fields. Because of the significant bank and bed erosion in the upstream reaches, and reduced conveyance in the downstream reaches, fields were inundated during high flows. The two-stage cross-section was constructed on excavating a floodplain on one side of the channel and leaving the opposite side and bottom intact to prevent digging the stream bed. The flood terrace has so far been large enough to prevent the brook to flood to the arable areas. Spawning brown trout have been monitored downstream in autumn 2010 and 2011, showing that no harm for fish was done by the excavation. There can also be expectet increase in trout habitats in the excavated section of upstreams, with the help of further restoration.

Monitoring surveys and results

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Lessons learnt

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Image gallery


Building the floodplain by the Ritobäcken Brook in 2010 (photo: Kari Koppelmäki)
Ritobacken brook_the excavated flood terrace (photo: J.Jormola)
Ritobacken brook_autumn 2005 (photo: Auri Sarvilinna)
Ritobacken brook_spring 2006 (photo: Auri Sarvilinna)
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Catchment and subcatchment

Catchment

River basin district Southern Finland
River basin Sipoonjoki River

Subcatchment

River name Ritobäcken brook
Area category 10 - 100 km²
Area (km2) 12 km²
1,200 ha
Maximum altitude category
Maximum altitude (m)
Dominant geology Organic (i.e. Peat)
Ecoregion Fenno-Scandian Shield
Dominant land cover Intensive agriculture
Waterbody ID



Other case studies in this subcatchment: Ritobäcken-environmentally preferable two-stage drainage channels


Site

Name Cathment of Ritobäcken Brook
WFD water body codes
WFD (national) typology
WFD water body name
Pre-project morphology Sinuous, Straightened
Reference morphology over-widened
Desired post project morphology
Heavily modified water body No
National/international site designation EU - Special Area of Conservation
Local/regional site designations
Protected species present No
Invasive species present No
Species of interest Brown trout (Salmo trutta)
Dominant hydrology Ephemeral
Dominant substrate
River corridor land use Intensive agriculture (arable)
Average bankfull channel width category
Average bankfull channel width (m)
Average bankfull channel depth category 0.5 - 2 m
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category
Average channel gradient 0.002
Average unit stream power (W/m2)


Project background

Reach length directly affected (m)
Project started 2009/01/01
Works started 2010/01/01
Works completed 2010/01/01
Project completed
Total cost category
Total cost (k€)
Benefit to cost ratio
Funding sources Ministry of Agriculture and Forestry; Ministry of Environment; Regional ELY-centre; and EU

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 invasive species
Hydromorphology Continuity for organisms, Width & depth variation, Structure & condition of riparian/ lake shore zones
Biology Fish: Species composition, Fish: Abundance, Fish: Disturbance-sensitive species, Fish: Age structure
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Adding sinuosity, Re-introducing stones, Introduction of gravel
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

Link Description
http://www.balticdeal.eu/Paljok Farm/Baltic Deal.mht Information about restauration of the Ritobacken brook
http://civil.aalto.fi/en/research/water/research/environmental hydraulics/sediment processes/ Physical sediment processes in environmental channels
http://www.restorerivers.eu/Portals/27/Ritob%C3%A4cken%20brook,%20Finland.pdf Restoration of Ritobäcken brook

Supplementary Information

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