Case study:Goshen Weir removal project, River Roch, Bury

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Location: 53° 34' 41", -2° 17' 13"
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Project overview

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Status Complete
Project web site
Themes Fisheries, Flood risk management, Habitat and biodiversity, Hydromorphology
Country England
Main contact forename Gary
Main contact surname Morris
Main contact user ID User:Gjmorris
Contact organisation Environment Agency
Contact organisation web site http://http://www.environment-agency.gov.uk/
Partner organisations River Restoration Centre, APEM Ltd, Irwell Rivers Trust
This is a parent project
encompassing the following
projects
Before and after removal (Goshan Weir)

Project summary

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Goshan weir on the River Roch in Bury was severely constraining the river corridor and restricting fish passage upstream. The weir removal was the largest attempted at the time, approx 1 km downstream of Gigg lane weir that had previously collapsed.

The weir was carefully removed by Environment Agency operations delivery operatives. Some consultancy pre-app work was undertaken by APEM that included the removal strategy to take out middle 60% and leave in the bankside lengths of the weir. This was to try and centralise the flow and take pressure of the river banks, especially the outer right hand bank.

This is one of the larger weirs that has been removed as part of the Irwell WFD ‘Good ecological potential’ project.

Monitoring surveys and results

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Five monitoring methods
Expert opinion and observation drawing upon in-house geo-morphological expertise
Habitat mapping survey
Fixed point photography survey (manually taken and via time lapse cameras)
Invertebrate surveys (planned, as of May 2014, as easement works are currently being undertaken on Kirklees Brook by Irwell Rivers Trust)
Fisheries survey (planned, as of May 2014, as above)

Lessons learnt

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The results are plain to see. Cumulative benefits.

The video footage shows how the angle of the weir originally directs flow to the inside of the bend. Once removed a more natural flow to the outer bend is established, with large sand and gravel deposits on the inner bend quickly burying the weir remains. The river quickly thins its width at the weir site. This also happened at the Gigg Lane weir site further upstream. One difficulty highlighted by this work is knowing just where to go to collect good data. It became evident that a large amount of erosion occurred at the top of the upper weir, an area that we were not monitoring. By focussing on the events close to our own intervention we saw little of what happened further upstream.

Problems with camera theft for time lapse work. Cameras for the Irwell Rivers Trust considrered disposable and data valued more than equipment.


Image gallery


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Catchment and subcatchment

Catchment

River basin district North West
River basin Irwell

Subcatchment

River name River Roch (Spodden to Irwell)
Area category 100 - 1000 km²
Area (km2)
Maximum altitude category 200 - 500 m
Maximum altitude (m) 282
282 m
0.282 km
28,200 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Suburban
Waterbody ID GB112069064600



Site

Name
WFD water body codes GB112069064600
WFD (national) typology
WFD water body name River Roch (Spodden to Irwell)
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)
Project started
Works started 2012/09/10
Works completed 2012/09/10
Project completed
Total cost category
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
Monitoring



Reasons for river restoration

Mitigation of a pressure Barriers to fish migration
Hydromorphology Continuity for organisms, Continuity of sediment transport
Biology Fish
Physico-chemical
Other reasons for the project


Measures

Structural measures
Bank/bed modifications Weir removal/modification for easement of fish passage
Floodplain / River corridor
Planform / Channel pattern
Other
Non-structural measures
Management interventions
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

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

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Supplementary Information

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