Case study:River Little Ouse at Thetford: Difference between revisions
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Revision as of 16:11, 16 July 2013
This case study is pending approval by a RiverWiki administrator.
Project overview
Status | In progress |
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Project web site | |
Themes | Flood risk management, Habitat and biodiversity |
Country | England |
Main contact forename | Chris |
Main contact surname | Gregory |
Main contact user ID | |
Contact organisation | British Trust for Ornithology |
Contact organisation web site | http://www.bto.org/ |
Partner organisations | |
Parent multi-site project | |
This is a parent project encompassing the following projects |
No |
Project summary
In 1991 the site and adjacent land were purchased by the BTO to create a wetland bird reserve. The Little Ouse had previously been straightened and flowed in a trapezoidal channel. In-stream habitat was poor, macrophytes were confined mainly to the shallow margins and the substrate was dominated by sand with some silt and gravel.
The Environment Agency were approached to assist with restoring flows to the original, meandering course which remained as a damp depression. By restoring flows to the old channel 900m of diverse river habitat with varied morphology and a connection to the floodplain was gained.
Problems have been experienced with the breaching of several banks at meanders and the development of permanently ponded areas (the original design was aimed at encouraging seasonal inundation to create suitable nesting habitats for waders such as lapwing). Several attempts have been made to repair these breaches with techniques such as blue clay banks and pre-seeded coir matting
Further remediation works are planned for September 2013 and will consist of the creation of 'living revetments'. The approximate cost of this additional work is £6,000.
Monitoring surveys and results
Lessons learnt
Catchment and subcatchment
Site
Name | River Little Ouse at Thetford |
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WFD water body codes | GB105033043090 |
WFD (national) typology | |
WFD water body name | |
Pre-project morphology | Artificial channel, Straightened, trapezoidal |
Reference morphology | Sinuous meander |
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 | Wading birds (e.g. Lapwing) |
Dominant hydrology | |
Dominant substrate | Gravel |
River corridor land use | Agriculture (arable) |
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) | 900900 m <br />0.9 km <br />90,000 cm <br /> |
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Project started | 1994/04/01 |
Works started | |
Works completed | |
Project completed | 1994/07/01 |
Total cost category | 10 - 50 k€ |
Total cost (k€) | 17.317.3 k€ <br />17,300 € <br /> |
Benefit to cost ratio | |
Funding sources |
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
Measures
Structural measures
| |
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Bank/bed modifications | Creation of pools and riffles |
Floodplain / River corridor | Creation of backwater and ponds, New habitats construction, Reconnect and restore historic aquatic habitats |
Planform / Channel pattern | Re-connect old meander |
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 | |||
Width & depth variation | No | Yes | Yes | No | No |
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
Image gallery
Additional documents and videos
Additional links and references
Link | Description |
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Supplementary Information
Edit Supplementary Information