Case study:Drayton

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Location: 52° 30' 55", -0° 47' 13"
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Project overview

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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
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Project summary

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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

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Lessons learnt

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Catchment and subcatchment

Catchment

River basin district Anglian
River basin Welland

Subcatchment

River name Welland
Area category 1000 - 10000 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 10
10 m
0.01 km
1,000 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB105031050680



Other case studies in this subcatchment: Welland for People and Wildlife Project


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) 1700
1,700 m
1.7 km
170,000 cm
Project started
Works started 2011/09/01
Works completed
Project completed 2011/12/01
Total cost category 50 - 100 k€
Total cost (k€) 70
70 k€
70,000 €
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 Deflectors, Bank stabilisation, Cattle drinkers, Introduction of gravel
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



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

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