Case study:Burn of Mosset, Forres: Difference between revisions
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Since construction in 2008 the scheme is effectively storing large wood and sediment, with a large sediment outwash fan forming at the upstream breach. A small amount of adaptive management has been required at the upstream breach due to erosional events interacting with woody material in the channel. Measures were taken to ensure that a further breach of the old channel did not occur, as this could have led to flooding of a significant area of agricultural land. | Since construction in 2008 the scheme is effectively storing large wood and sediment, with a large sediment outwash fan forming at the upstream breach. A small amount of adaptive management has been required at the upstream breach due to erosional events interacting with woody material in the channel. Measures were taken to ensure that a further breach of the old channel did not occur, as this could have led to flooding of a significant area of agricultural land. | ||
In 2010 the scheme was awarded an "environmentally sustainable construction" commendation by the Institute of Civil Engineers. | In 2010 the scheme was awarded an "environmentally sustainable construction" commendation by the Institute of Civil Engineers. | ||
This project is part of the UK River Restoration Center's manual of river restoration techniques (update due to be published in late 2013). | |||
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{{Case study subcatchment | {{Case study subcatchment |
Revision as of 09:36, 16 July 2013
This case study is pending approval by a RiverWiki administrator.
Project overview
Status | Complete |
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Project web site | |
Themes | Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology |
Country | Scotland |
Main contact forename | Matthew |
Main contact surname | Hardwick |
Main contact user ID | |
Contact organisation | Royal HaskoningDHV |
Contact organisation web site | |
Partner organisations | |
Parent multi-site project | |
This is a parent project encompassing the following projects |
No |
Project summary
The Burn of Mosset is a small gravel bed stream draining an area of 49km2. A Tributary of the River Findhorn, it flows north through the town of Forres before entering Findhorn bay. The town of Forres has a long history of flooding from the burn, with six flood events causing serious damage to property or disruption in the last fifty years.
The new Flood Alleviation Scheme (FAS) took two years to complete. It included the construction of an earth-filled embankment dam designed to allow for discharges up to 8.5 m3/s to flow through Forres, with excess floodwater temporarily stored behind the dam.
In addition to this, the upstream storage area has been designed to create an extensive natural sediment accretion zone (for sand, gravel and large wood). This will reduce the risk of sediment or other debris blocking the dam control structure. The scheme also aimed to create a mosaic of river and floodplain habitats, by working with natural processes to develop a multi-thread (anabranched) system.
This was achieved by breaching the existing embanked channel which ran around a field boundary at two points, allowing flow to spill out across the open field, before re-joining the original channel just upstream of the dam. Tress were planted across the site to create a wet woodland habitat.
Since construction in 2008 the scheme is effectively storing large wood and sediment, with a large sediment outwash fan forming at the upstream breach. A small amount of adaptive management has been required at the upstream breach due to erosional events interacting with woody material in the channel. Measures were taken to ensure that a further breach of the old channel did not occur, as this could have led to flooding of a significant area of agricultural land.
In 2010 the scheme was awarded an "environmentally sustainable construction" commendation by the Institute of Civil Engineers.
This project is part of the UK River Restoration Center's manual of river restoration techniques (update due to be published in late 2013).
Monitoring surveys and results
Lessons learnt
Catchment and subcatchment
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(affects all case studies in this subcatchment)
Catchment
River basin district | Scotland RBD |
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River basin | Findhorn |
Subcatchment
River name | Burn of Mosset |
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Area category | |
Area (km2) | 13001,300 km² <br />130,000 ha <br /> |
Maximum altitude category | |
Maximum altitude (m) | |
Dominant geology | Organic |
Ecoregion | Great Britain |
Dominant land cover | Moorland/heathland, Woodland |
Waterbody ID |
Site
Name | Forres Flood Alleviation Scheme |
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WFD water body codes | 23021 |
WFD (national) typology | Lowland, Small, Siliceous |
WFD water body name | Mosset Burn Altyre to Forres |
Pre-project morphology | Straightened, Embanked, Over-widened |
Reference morphology | Anastomosing, Pool-riffle |
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 | Quick run-off |
Dominant substrate | Gravel, Cobble |
River corridor land use | Improved/semi-improved grassland/pasture, Moorland/heathland, Woodland |
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
Reach length directly affected (m) | 500500 m <br />0.5 km <br />50,000 cm <br /> |
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Project started | 2008/01/01 |
Works started | |
Works completed | |
Project completed | 2008/12/31 |
Total cost category | |
Total cost (k€) | 116116 k€ <br />116,000 € <br /> |
Benefit to cost ratio | |
Funding sources |
Cost for project phases
Phase | cost category | cost exact (k€) | Lead organisation | Contact forename | Contact surname |
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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 | Flood risk management |
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Hydromorphology | |
Biology | |
Physico-chemical | |
Other reasons for the project |
Measures
Structural measures
| |
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Bank/bed modifications | Create breaches in the bank |
Floodplain / River corridor | Floodplain reconnection, Riparian tree planting |
Planform / Channel pattern | Allow future natural channel changes to occur |
Other | |
Non-structural measures
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Management interventions | |
Social measures (incl. engagement) | |
Other |
Monitoring
Hydromorphological quality elements
Element | When monitored | Type of monitoring | Control site used | Result | ||
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Before measures | After measures | Qualitative | Quantitative |
Biological quality elements
Element | When monitored | Type of monitoring | Control site used | Result | ||
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Before measures | After measures | Qualitative | Quantitative |
Physico-chemical quality elements
Element | When monitored | Type of monitoring | Control site used | Result | ||
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Before measures | After measures | Qualitative | Quantitative |
Any other monitoring, e.g. social, economic
Element | When monitored | Type of monitoring | Control site used | Result | ||
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Before measures | After measures | Qualitative | Quantitative |
Monitoring documents
Image gallery
Additional documents and videos
Additional links and references
Link | Description |
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http://www.royalhaskoning.co.uk/en-gb/Publication/Documents/projects/forres-flood-alleviation-scheme.pdf | Royal Haskoning- Forres Flood Alleviation Scheme |
http://www.moray.gov.uk/downloads/file86456.pdf | Moray council- Forres FAS |
Supplementary Information
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