Case study:Meander reinstatement on the River Wensum at the Ryburgh Loop
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site||http://www.therrc.co.uk/rrc_case_studies1.php?csid=76|
|Themes||Fisheries, Habitat and biodiversity|
|Main contact forename||Rob|
|Main contact surname||Dryden|
|Main contact user ID|
|Contact organisation||Environment Agency|
|Contact organisation web site||http://www.environment-agency.gov.uk|
|Partner organisations||Wensum River Restoration Strategy|
|Parent multi-site project|
| This is a parent project
encompassing the following
Site background The River Wensum is a chalk SSSI and SAC river currently stated as being in unfavourable condition. Located to the southeast of the Norfolk town of Fakenham the meander loop at Great Ryburgh Common was bypassed in the 1950’s when the River Wensum was straightened, widened and deepened as part of a land drainage improvement scheme.
The river restoration work undertaken involved reinstating a former meander, increasing channel sinuosity and flow diversity. The work was part of the wider River Wensum Restoration Project.
Objectives To re-instate the natural river form and function by re-connecting the old meander. It was designed so that at normal flows all the flow would go down the old meander and at high flow, part of the flow would be diverted into the straightened channel. To re-connect the old meander by removing the silt layer from the old channel whilst retaining the existing gravel substrate where it still existed.
Design The old meander was carefully excavated leaving the riverbed gravels intact where they already existed. In addition new gravels were added to create shallow glides. Deeper pools were dug to provide refuge ares for fish and other aquatic species. The existing straightened channel was plugged such that in normal flow conditions, the river flows around the re-connected meander. The straightened channel therefore acts as a flood relief channel at times of high flow and as a quiet backwater during normal flow. In addition, channel narrowing was achieved by creating a bund along the line of the new bank, and this was covered with coir matting and was planted up with live plants.
Subsequent performance – RRC’s views (2011) Eighteen months on, the site is fully vegetated and functioning well as a re-connected meander. The original gravel bed was exposed during excavation and the use of adaptive management allowed these original features to be incorporated into the on-the-ground works. The Environment Agency OPS team was used to do the works as they had experience of doing similar work(at Bintree further down the catchment). Prior to re-meandering, the channel was straightened and over-wide. The project has recreated the natural chalkstream habitat, with pool and riffle sequences. The substrate now has macrophytes growing along much of its length. By allowing high flows to pass down the old straightened channel the flood capacity has been increased, and during normal flows the old straightened channel acts as a backwater habitat.
Monitoring surveys and results
Catchment and subcatchment
Select a catchment/subcatchment
Other case studies in this subcatchment: Great Ryburgh End Restoration Scheme, River rehabilitation on the River Wensum at Swanton Morley, Sculthorpe Moor Restoration Scheme, Wensum River Restoration and Floodplain Enhancement, Wensum River Restoration and Floodplain Enhancement, Pensthorpe
Cost for project phases
Supplementary funding information
paid in pound 105,000
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos