Case study:River Skerne- Life project

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Location: 54° 32' 11", -1° 31' 48"
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Project overview

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Status Complete
Project web site
Themes Economic aspects, Habitat and biodiversity, Social benefits, Water quality, Urban
Country England
Main contact forename Ulrika
Main contact surname Åberg
Main contact user ID User:UlrikaRRC
Contact organisation River Restoration Centre
Contact organisation web site http://www.therrc.co.uk
Partner organisations European Commission (LIFE funding), River Restoration Project (now River Restoration Centre), Darlington Borough Council, Environment Agency, Northumbrian Water, English Nature (now Natural England), Countryside Commission, Heritage Lottery Fund
Parent multi-site project

Case_study:River restoration: Benefits for integrated catchment management

This is a parent project
encompassing the following
projects
No
Aerial view of the completed Skerne works

Project summary

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Background: The River Skerne is a tributary of the River Tees in North East England. The restored reach lies in a sub-urban area on the outskirts of Darlington, County Durham. During the last 150 years, the River Skerne has been heavily modified as a result of industrialisation and urbanisation. Between 1850 and 1945 the river was straightened and channelized, and the river corridor was markedly narrowed. Widening and deepening was undertaken in the 1950s and the 1970s, and new housing developments were built along the entire north side of the river. The area has a rich industrial heritage including the first railway company Stockton and Darlington. The Skerne (railway) Bridge, which can be found just downstream of the site, was pictured on the old five pound notes.

Restoration: The River Skerne was included in a joint initiative between England and Denmark to demonstrate best practice in urban and rural river rehabilitation and encourage river restoration in Europe. The wider aim was to promote further river restoration and demonstrate how river restoration could provide multiple benefits such as enhancement in wildlife, landscape, recreation, water quality, fisheries, amenities and other local interests.

The River Skerne Restoration Project was supported by European Commission LIFE funding with matched financial and in-kind support from the Environment Agency, Darlington Borough Council, Northumbrian Water English Nature and the Countryside Commission. The project also attracted additional Heritage Lottery Fund support to complete the original 'full scheme' aspirations. The project was managed by the River Restoration Project (the precursor to the River Restoration Centre) with significant additional partner management input from Northumbrian Water and The Environment Agency in leading the project and working group.

The restoration of 2 km of the Skerne was initiated in July 1995. Much of the floodplain had been raised by old industrial waste tipping, with gas and sewer pipes running alongside the river. As a result of these constraints, restoration opportunities were severely limited - typical of urban rivers elsewhere. At the upstream end, instream deflectors and a coarse sediment riffle were installed to enhance flow variability and habitat diversity. Further downstream four new meanders were cut across the old channel, which was used to create two backwaters. Soft revetments – such as willow mattress, willow spiling, underwater rock layer, fibre rolls, and geotextiles – were used on the outer meander bends to prevent erosion towards the gas main. As a flood water retention measure, about 25,000 m3 of spoil was removed from the river banks. This also aimed to increase the lateral connectivity between the river and the adjacent floodplain. The spoil was later used for landscaping purposes.

Hundreds of nearby properties were checked for misconnections by Northumbrian Water and thirteen ugly surface water outfalls were replaced with underground inspection /collection chambers that firstly intercept pollution and then discharge the water into the river below water level. New footpaths were constructed and a planting scheme engaging local residents carried out. At the downstream end of the restored section a new footbridge was constructed, designed to resemble a locomotive as a tribute to the historical significance of the Skerne Bridge.

Monitoring surveys and results

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Pre-monitoring Before restoration started, several indicators were monitored to see what the reference situation was for post-restoration monitoring.

Ecology

  • Macrophytes - monitored qualitatively, number of species found per 500 meter channel length.
  • Macro-invertebrates - species richness and abundance, and as an indicator for water quality/organic pollution (BMWP).
  • Fish - biomass, fish density and species richness.
  • Birds were monitored by assessing the assemblage of breeding birds and abundance.

Hydro-morphology

  • Geomorphological - channel cross sections and physical habitat mapping.
  • Water quality - suspended sediment concentration and concentration of nitrogen and phosphorus (measured at monthly intervals).
  • Modelling of flood frequency.

Social-economic factors

  • Economic benefits for six categories (water quality, amenity, fisheries, agriculture, flood defence and recreation) were calculated.
  • Public perception was measured using a semi-structured questionnaire survey.
  • 90% of the visitors to the River Skerne in Darlington were quite or very satisfied with the restoration of the river, 15 years on from the completion of the work. Revisiting the River Skerne: The long-term social benefits of river rehabilitation. Åberga and Tapsell. Landscape and Urban Planning 113 (2013) 94– 103


Post-monitoring

  • Repetition of pre-monitoring was carried out 1 and 2 years after restoration. Due to its importance as a demonstration project, further monitoring been carried out by Master and PhD students.
  • Revisiting the River Skerne: The long-term social benefits of river rehabilitation. Åberga and Tapsell. Landscape and Urban Planning 113 (2013) 94– 103

Expectations and Response:

  • It was expected that the existing unpleasant park would improve in aesthetic quality and as a public recreation area. The river would feature more natural elements and dynamics.

Ecology

One year after restoration, macrophyte species richness increased above pre-restoration levels with 30%. The downstream control site did not seem to be affected by the restoration measures. No initial changes were found in the macro-invertebrate community, but long term surveys have shown an increase in niche specific macro-invertebrate families sensitive to siltation and/or organic pollution. The fish species richness increased with Roach (Rutilus rutilus) and Chub (Leuciscus cephalus), but the total number of caught individuals was small with only 16 fish of 4 species. The appearance of new fish species can be related to the new fish pass below Darlington. Unfortunately, several severe pollution incidents may have largely eliminated recolonizing fish populations.

Hydro-morphology

The river length was increased with 13%. Longitudinal and cross-section variability in meandered section was limited due to flood risk management requirements. However, macrophyte growth has provided some flow and habitat diversity. The constructed riffle at the upstream end has provided habitat for macro-invertebrates sensitive to fine sediments which were not found in the section prior to restoration (e.g. the freshwater limpet Ancylidae, the riffle beetle Elmidae, the net-spinning caddis fly Hydropsychidae and the blackfly larvae Simuliidae).

The new channel profile with lower banks increased the out of bank flow to a maximum of 4.5 days per year. The lowering of the floodplain itself created more water storage and the flood protection level has remained unchanged.

Social

Local residents were engaged in the project from the planning phase and post-restoration assessment showed that 52% of the local residents ‘mostly’ and 30% ‘strongly’ approved the restoration works. A majority of 64% felt that the restoration scheme had achieved its objectives and 70% of the residents thought more wildlife had been attracted to the area. Long term monitoring has shown an increased support for the restoration scheme, with increasing number of satisfied local residents.


Overall, the Skerne project was a big social success. People were engaged in the project and very positive about the outcomes. The ecological status has improved, but it is still limited by the urban environment, (e.g. fixation of the river to protect infrastructure, and pollution from industry upstream).

Lessons learnt

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  • Engaging the local community is essential. This project employed a local Community Liaison Officer who was know to the local community and was on hand to answer questions, solve local issues and field queries to the technical working group and project board.
  • In these early days of river restoration the project showed what could be expected from a restoration project and how it develops (might be different from anticipated) – this needs to be built into decision making process
  • It is important to do a formal long-term management plan, and have a cooperating (and stable) land owner,
  • Each of the partner organisations applied their resources together to provide a wealth of in-kind work to boost the already significant works budget,
  • The project showed a whole suite of demonstration techniques (included in the Manual of River Restoration Techniques http://www.therrc.co.uk/rrc_manual.php)
  • The project clearly showed the complexity of a linear system (compared with ponds), and that it's difficult to distinguish success between different components • The project gave a big boost to river restoration in the UK and showed that it is possible to undertake “large scale” (for that time) projects,
  • Long-term monitoring (>3 years, especially of biological indicators) is crucial for accurate evaluation of success.


Image gallery


Skerne - meander 1 in 2001
Skerne - meander 2 in 2001
Skerne - locomotive footbridge in 2001
Skerne - backwater in 2005
Skerne - in flood 2004
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Catchment and subcatchment

Catchment

River basin district Northumbria
River basin Tees

Subcatchment

River name Tees US Low Worsall
Area category 1000 - 10000 km²
Area (km2)
Maximum altitude category 100 - 200 m
Maximum altitude (m) 152
152 m
0.152 km
15,200 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Arable and Horticulture
Waterbody ID GB103025072593



Site

Name River Skerne at Haughton le Skerne
WFD water body codes GB103025072593
WFD (national) typology
WFD water body name Tees US Low Worsall
Pre-project morphology Straight
Reference morphology Low gradient passively meandering
Desired post project morphology Low gradient passively meandering
Heavily modified water body Yes
National/international site designation
Local/regional site designations
Protected species present No
Invasive species present Yes
Species of interest
Dominant hydrology Quick run-off
Dominant substrate Sand, Silt
River corridor land use Urban, Parklands garden
Average bankfull channel width category 5 - 10 m
Average bankfull channel width (m)
Average bankfull channel depth category 0.5 - 2 m
Average bankfull channel depth (m)
Mean discharge category
Mean annual discharge (m3/s)
Average channel gradient category Less than 0.001
Average channel gradient
Average unit stream power (W/m2)


Project background

Reach length directly affected (m) 2000 m
2 km
200,000 cm
Project started 1993/04/01
Works started 1995/07/01
Works completed 1995/09/01
Project completed 1997/01/01
Total cost category
Total cost (k€) 2750
2,750 k€
2,750,000 €
Benefit to cost ratio
Funding sources EU LIFE Programme, Heritage Lottery Fund (HLF), Northumbrian Water, Environment Agency, Darlington Borough Council, Countryside Commission, English Nature

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 Riparian development
Hydromorphology Quantity & dynamics of flow, Width & depth variation, Structure & condition of riparian zones
Biology Fish: Species composition, Invertebrates, Macrophytes
Physico-chemical Oxygen balance
Other reasons for the project Landscape enhancement, Recreation


Measures

Structural measures
Bank/bed modifications Re-grading and lowering, Deflectors
Floodplain / River corridor Lowering of floodplain, Creation of wetland, Protect/restore riparian zone
Planform / Channel pattern Adding sinuosity, Creation of backwater
Other Creation of new bicycle path, Revetting and supporting river banks
Non-structural measures
Management interventions More sensitive floodplain maintenance
Social measures (incl. engagement) Citizen participation in the restoration project
Other Participation in works, Information provision, Participation in design, Consultation


Monitoring

Hydromorphological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Channel pattern/planform Yes Yes Yes No No Improvement
Width & depth variation No Yes Yes No No Improvement
Flow velocities No Yes Yes No No

Biological quality elements

Element When monitored Type of monitoring Control site used Result
Before measures After measures Qualitative Quantitative
Fish: Species composition Yes Yes No Yes Yes Inconclusive
Invertebrates Yes Yes No Yes Yes Improvement
Macrophytes Yes Yes No Yes No Improvement

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
Public use of community park Yes Yes Yes Yes Yes Improvement


Monitoring documents



Additional documents and videos


Additional links and references

Link Description
http://http://www.therrc.co.uk/projects/skerne brochure.pdf RRC report
http://http://en.wikipedia.org/wiki/River Skerne Wikipedia link
http://wiki.reformrivers.eu/index.php/River Skerne EU-LIFE project REFORM link
http://www.therrc.co.uk/rrc publications.php All published documents on the project

Supplementary Information

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