Case study:Upper River Witham : Easton

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Location: 52° 49' 45.97" N, 0° 37' 31.86" W

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Project overview

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Status	Complete
Project web site
Themes	Habitat and biodiversity
Country	England
Main contact forename	Matt
Main contact surname	Parr
Main contact user ID
Contact organisation	Environment Agency
Contact organisation web site	http://www.gov.uk/government/organisations/environment-agency
Partner organisations
Parent multi-site project	Upper Witham Restoration
This is a parent project encompassing the following projects	No

Post Restoration

Project summary

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Weir removal to restore bed gradient; channel narrowing and flow deflection to create flow variation and beneficial bed scour using log flow deflectors (vanes), open and enclosed log/faggot and brushwood mattresses (silt-traps) and earth, turf and silt filled log- or faggot-fronted enclosures; creation of sections of 2-stage channel and enhancing marginal wetland habitat by reprofiling eroded banks; excavation of pools in the river bed; increasing in-stream woody habitat by securing existing deadwood and hinging and pinning (layering) live riverside trees; and fencing to prevent bank erosion by livestock.

Project Objectives The pre-project surveys and assessments led to the identification of the following objectives for the enhancement scheme:

Reduce the impact of sediment inputs as a result of erosion caused by livestock.
Repair eroded banks and protect them from erosion in the future.
Trap sediment already in the system.
Improve flows and natural cleansing of spawning gravels.
Improve light levels in over-shaded sections.
Improve habitat for trout, coarse fish and native white-clawed crayfish.
Ensure that historic features within the Grade II Listed Historic Park and Garden are protected.

Three separate schemes based on these objectives were prepared.

Monitoring surveys and results

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In addition to the established annual fish monitoring programme downstream of Easton Walled Garden and invertebrate sampling at Easton Lane Bridge, visual inspections of the enhanced reach will be undertaken, and the fixed point photographic record will be updated to monitor the integrity and performance of the in-stream enhancements and record any changes they are making to river morphology. Post-works redd (trout spawning nest) surveys were undertaken upstream and downstream of Easton Lane. 6 redds were located in the upstream (Easton Park) section, but none were located downstream. These surveys provide a baseline for future monitoring.

Lessons learnt

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1. The greatest detrimental impact upon river habitat is the legacy of past channel engineering. Straightening and widening of the channel and lowering of the river bed have disrupted/destroyed the natural pool-riffle sequence and disconnected the floodplain. The process of the river recovering these natural characteristics is very slow (centuries) because of the naturally low energy of the river and limited supply of coarse sediment.

2. Habitat improvement measures within the existing channel have generally been unsuccessful. Installed in-stream structures have not had the desired effect of creating scour and producing depth variation. This is because of the resistant nature of the predominantly clay substrate, loss of sediment (gravel) to historic channel engineering and lack of sediment (gravel) supply/retention within the present channel dimensions. Introduced brushwood and large woody material have improved cover and fish-holding habitat, but have not fundamentally changed the channel shape.

3. The weir removal at Easton has restored fish passage and better habitat to the formerly impounded reach upstream, although the above constraints (point 1) remain. Trout numbers observed in this reach indicate a recovery from past pollution incidents.

4. Where the constraints have been addressed by realigning and re-naturalising the channel at Grange Farm, habitat improvement has been more successful, although further intervention is required. Introduced gravel has been displaced in high flows and needs to be replaced with larger calibre material which will remain stable and restore the designed pool-riffle sequence. The abrupt change in valley floor gradient at this site constrained the design of the new channel and caused this situation; this is unusual and should not be a deterrent to similar river restoration schemes elsewhere.

Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Edit the catchment and subcatchment details (affects all case studies in this subcatchment) Catchment River basin district Anglian River basin Witham Subcatchment River name Upper Witham Area category 10 - 100 km² Area (km2) Maximum altitude category Less than 100 m Maximum altitude (m) 4646 m <br />0.046 km <br />4,600 cm <br /> Dominant geology Calcareous Ecoregion Great Britain Dominant land cover Arable and Horticulture Waterbody ID GB105030056760 Other case studies in this subcatchment: Aubourn Rock Ramp and Habitat Works, Belton Floodplain Reconnection and River Restoration, Dysart Park, Grantham Habitat Improvement, Grantham Blue Green - Urban Reach, Little Ponton, Manthorpe Floodplain Reconnection, Papermill Weir Section in-channel restoration, River Witham Great Ponton, Stainby Road, Colsterworth, Syston and Barkston Restoration... further results Site Edit site Name Upper River Witham Easton WFD water body codes GB105030051570 WFD (national) typology WFD water body name Upper Witham Headwater to confluence Cringle Brook Pre-project morphology Reference morphology 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 Dominant substrate River corridor land use 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 Edit project background Reach length directly affected (m) Project started 01/10/2013 Works started Works completed Project completed Total cost category 50 - 100 k€ Total cost (k€) 6666 k€ <br />66,000 € <br /> Benefit to cost ratio Funding sources EA 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 Edit reasons for restoration Mitigation of a pressure Land drainage Hydromorphology Biology Fish Physico-chemical Phosphate Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Weir Removal, Berms, Flow Deflectors, Tree Hinging Floodplain / River corridor Fencing Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Physico-chemical quality elements Edit 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 Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Project Case Study Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information