Case study:Little Waltham Meadows Back Channel creation
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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|
|Themes||Habitat and biodiversity, Hydromorphology|
|Main contact forename||Kieren|
|Main contact surname||Alexander|
|Main contact user ID||User:KierenAlexander|
|Contact organisation||Essex Wildlife Trust|
|Contact organisation web site||http://www.essexwt.org.uk|
|Partner organisations||Essex and Suffolk Water (Northumbrian Water), Chelmer and Blackwater Catchment Partnership, Natural England, Environment Agency, Chelmer and Blackwater Navigation (Essex Waterways Ltd), Parish Councils and the Rural Communities Council for Essex, Landowners and farmers, Rivers Trust, Essex County Council, Essex Farming and Wildlife Advisory Group|
|Parent multi-site project|
| This is a parent project
encompassing the following
This is a multi-benefit project aimed at improving in channel morphological diversity, reducing the amount of diffuse pollution and sedimentation entering the main river Chelmer. It will also increase the amount of riparian habitat along the River Chelmer and enhance the resilience of the wet woodland.
This project was funded by the Catchment restoration fund, as part of the Essex Healthy headwaters scheme. The earthworks were undertaken in late Summer, early Autumn 2014.
The aims of this project were achieved in the first instance by the creation of a new 280 backwater channel with three settling ponds and a sluice structure. The back channel connects with the river and an existing culvert/drainage point off the nearby main road. The ponds and back channel in the first instance allow for any nitrate and phosphate heavy water coming through the culvert to be settled and filtered. The back channel is also excellent in times of high flows at providing fish refuges, especially for fish fry which are in danger of being washed downstream in flood events. It will also provide an interface between the river and the bank side which will allow some interesting and diverse flora to develop. Finally, by connecting the river with the floodplain it creates additional riparian habitat and has a small but meaningful impact on flooding by increasing storage in the floodplain, outside of Chelmsford.
The other aim of the project, namely to increase the resilience of the wet woodland. Was created by installing a sluice at the far end of an existing ditch. Unlike the other sluice this captures rain water and holds it back on the landward side, this has been set at a level that is higher than previous levels and will effect a raise in water off approximately 50 centimeters. The increased water levels have also allowed for additional planting to be undertaken that will extend the water by over half a hectare, there has also been some limited earthworks to spread the water over a wider area.
These works will keep the woodland wetter in the summer months, keeping Bramble under control and allowing a further establishment of the flora normally associated with wet woodlands.
Monitoring surveys and results
There has been a full pre-works survey conducted by Essex Ecological Consultancy service which has established a baseline index of key invertebrates and flora.
Post works it is hoped that this survey can repeated once the site has settled down to allow an accurate summary of the effect of the works. There will also be adhoc surveys of any flora development in time.
The sluice at the Wet woodland presented some issues post project, with an unacceptable level of water loss through the frame. This was rectified and is now operating at a normal level. However, some thought must be given to the purpose of the sluice and this should inform the design of the sluice. Holding water back requires a strong but not particularly flexible structure.
Any back channel is relies heavily on the correct levels being established, this relies on understanding the local conditions i.e. any local impoundments this may not be easily recognized so early and often discussions with the EA or the local Drainage board are necessary.
Catchment and subcatchment
Select a catchment/subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos