Case study:Restorations of Ritobäcken brook: Difference between revisions
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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. | 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. | ||
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|Caption=Building the floodplain by the Ritobäcken Brook in 2010 (photo: Kari Koppelmäki) | |||
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|Caption=Ritobacken brook_the excavated flood terrace (photo: J.Jormola) | |||
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|Caption=Ritobacken brook_autumn 2005 (photo: Auri Sarvilinna) | |||
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|Caption=Ritobacken brook_spring 2006 (photo: Auri Sarvilinna) | |||
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Revision as of 10:34, 6 September 2013
Project overview
Status | Complete |
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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 |
Project summary
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.
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Catchment
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Other case studies in this subcatchment: Ritobäcken-environmentally preferable two-stage drainage channels
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Reasons for river restoration
Measures
MonitoringHydromorphological quality elements
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