Case study:Drayton
This case study is pending approval by a RiverWiki administrator.
Project overview
| Status | Complete |
|---|---|
| Project web site | |
| Themes | Habitat and biodiversity |
| Country | England |
| Main contact forename | Environment Agency Customer Contact |
| Main contact surname | Anglian Northern Area |
| Main contact user ID | |
| Contact organisation | Environment Agency |
| Contact organisation web site | http://www.environment-agency.gov.uk |
| Partner organisations | Welland Rivers Trust, Wild Trout Trust |
| Parent multi-site project | |
| This is a parent project encompassing the following projects |
No |
Project summary
The scheme was implemented by the Environment Agency with the co-operation and agreement of the adjacent landowners (Matthew and Melanie Robinson and Alister Brooke-Clarke) and in-kind support from the Welland Rivers Trust and the Wild Trout Trust.
Summary of Techniques: Faggot, woody debris and coir roll flow deflectors; channel pinching using faggots, woody debris and coir rolls; introduction of gravels to augment and create riffles; bank toe protection using rock and coir; new cattle drinkers; riverside fencing; selected tree works including crown-lifting and pollarding; new tree and shrub planting; artificial otter holt construction.
Background During the 1970s the River Welland was significantly modified. The natural river morphology was altered to improve land drainage and flood water discharge. The river was deepened; many meanders, pools, riffles and glides were removed; and the river was constricted within high, straight banks. High winter flood flows and poor land management practices now cause significant bank erosion and sedimentation. Prior to modification a high proportion of these nutrient-rich sediments would have been deposited on the floodplain, providing rich grazing pasture, but, as a result of the flood defence works, a large proportion of these sediments now remain in the channel, degrading habitats including fish spawning gravels.
Monitoring surveys and results
Lessons learnt
Catchment and subcatchment
Edit the catchment and subcatchment details
(affects all case studies in this subcatchment)
Site
| Name | River Welland downstream of Ashley gauging station |
|---|---|
| WFD water body codes | GB105031050580 |
| WFD (national) typology | Calcareous |
| WFD water body name | Welland |
| Pre-project morphology | Straightened, Over deepened, Low gradient passively meandering, Pool-riffle, Run-glide |
| Reference morphology | |
| Desired post project morphology | |
| Heavily modified water body | Yes |
| National/international site designation | EU - WFD protected area (drinking water, shellfish etc.) |
| Local/regional site designations | |
| Protected species present | Yes |
| Invasive species present | No |
| Species of interest | otter; brown trout |
| Dominant hydrology | |
| Dominant substrate | Gravel |
| River corridor land use | Improved/semi-improved grassland/pasture |
| 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) | 17001,700 m <br />1.7 km <br />170,000 cm <br /> |
|---|---|
| Project started | |
| Works started | 2011/09/01 |
| Works completed | |
| Project completed | 2011/12/01 |
| Total cost category | 50 - 100 k€ |
| Total cost (k€) | 7070 k€ <br />70,000 € <br /> |
| Benefit to cost ratio | |
| Funding sources | Environment Agency |
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
| Mitigation of a pressure | Flood risk management, Land drainage |
|---|---|
| Hydromorphology | Continuity of sediment transport |
| Biology | Fish |
| Physico-chemical | Nutrient concentrations |
| Other reasons for the project |
Measures
Structural measures
| |
|---|---|
| Bank/bed modifications | Creation of deflectors, Bank stabilisation, Introducing gravel, cattle drinkers |
| Floodplain / River corridor | Tree planting, tree management |
| Planform / Channel pattern | Channel narrowing |
| Other | |
Non-structural measures
| |
| Management interventions | Fencing |
| 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 | |||
| Substrate conditions | No | No | No | No | No | |
Biological quality elements
| Element | When monitored | Type of monitoring | Control site used | Result | ||
|---|---|---|---|---|---|---|
| Before measures | After measures | Qualitative | Quantitative | |||
| Fish | Yes | No | No | No | No | |
| Invertebrates | Yes | No | No | No | No | |
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 |
|---|---|
| http://www.ecologylink.com | Ecology Link Ltd - Ecological survey and scheme design |
| http://www.water-lines.co.uk | Water-Lines Solutions - supplied the coir rolls |
Supplementary Information
Edit Supplementary Information