Difference between revisions of "Case study:River Pinn Enhancement near Ickenham"

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|Main contact forename=David
|Main contact forename=David
|Main contact surname=Holland
|Main contact surname=Holland
|Contact organisation=SALIX River and Wetland Services
|Contact organisation=Salix River & Wetland Services Limited
|Project picture=Salix1.png
|Project picture=Salix1.png
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|WFD water body code=GB106039023070
|WFD water body name=Pinn
|Heavily modified water body=No
|Protected species present=No
|WFD water body code=
|Invasive species present=No
|WFD (national) typology=
|WFD water body name=
|Pre-project morphology=
|Reference morphology=
|Heavily modified water body=
|Local site designation=
|Site designation=
|Protected species present=
|Invasive species present=
|Dominant hydrology=
|Dominant substrate=
|River corridor land use=
|Average bankfull channel width category=
|Avrg bankfull channel width=
|Average bankfull channel depth category=
|Avrg1 bankfull channel depth=
|Mean discharge category=
|Mn discharge=
|Average channel gradient category=
|Avrg channel gradient=
{{Project background
{{Project background

Latest revision as of 12:33, 6 June 2017

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Location: 51° 33' 17", -0° 27' 29"
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Project overview

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Status Complete
Project web site
Themes Habitat and biodiversity
Country England
Main contact forename David
Main contact surname Holland
Main contact user ID
Contact organisation Salix River & Wetland Services Limited
Contact organisation web site
Partner organisations
Parent multi-site project
This is a parent project
encompassing the following
Gravel being added to the channel

Project summary

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Salix designed and constructed a 40 metre enhanced channel and imported flint reject stone was used to create in channel features, two riffles and a point bar. Diverse marginal and bankside vegetation was established using mature pre-established coir rolls and pallets. Locally harvested tree trunks were used to create a double flow deflector. Additionally, a large backwater was created on line and just downstream of the enhanced reach.
A stream enhancement project at a gas pipeline river crossing as ecological mitigation to a degraded reach of stream as part of a major pipeline project. Salix were asked by Main Contractor Murphy Pipelines to assess a degraded reach of the River Pinn near Ickenham with the goal of enhancing the reach. The channel had been modified previously and was characterised by slow water flow, over deep and ponded with a silty bed and steep banks covered in nettles.

Monitoring surveys and results

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No post project monitoring has been done.

Lessons learnt

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Revisiting site in July 2009: The gravel has concentrated the low flows and revived water flow in the reach, and diverse marginal and bankside vegetation has established.

Image gallery


Catchment and subcatchment


River basin district Thames
River basin Colne


River name Pinn
Area category 10 - 100 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 156
156 m
0.156 km
15,600 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Suburban
Waterbody ID GB106039023070


WFD water body codes GB106039023070
WFD (national) typology
WFD water body name Pinn
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

Reach length directly affected (m) 40 m
0.04 km
4,000 cm
Project started 2009/01/01
Works started
Works completed 2009/01/01
Project completed
Total cost category 10 - 50 k€
Total cost (k€)
Benefit to cost ratio
Funding sources

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

Reasons for river restoration

Mitigation of a pressure Riparian development
Other reasons for the project


Structural measures
Bank/bed modifications Installation of coir rolls, Deflectors
Floodplain / River corridor
Planform / Channel pattern Creation of backwater, Creation of pools and riffles
Non-structural measures
Management interventions
Social measures (incl. engagement)


Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative

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

Supplementary Information

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