Latest revision as of 12:52, 30 July 2013

River Skerne EU-LIFE project

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General description

The river Skerne is a 40 km tributary of the river Tees. The source is located in the hills close to the village of Trimdon and the river confluences with the Tees at Hurworth Place. The project site lies in the city of Darlington.

The Skerne demonstration project was part of the River Demonstration Project together with the river Skerne and river Brede projects. This collaboration between British and Danish water managers tried to apply state-of-the-art restoration techniques and to demonstrate these projects to a wider audience of European water managers. It was the first river restoration project of this kind in the UK.

Pressures and Drivers

Historical management and increasing urbanization has diminished the natural dynamics of the river Skerne. The river has been channelized and deepened to increase flood protection and the floodplains have been elevated by industrial waste disposal. Waste water treatment plants have a negative influence on the water quality, while technical infrastructure such as sewer pipes and electric cables limit the available floodplain size even further.

The Life Demonstration Project has chosen this project location as example of river restoration in a restrictive urban environment.

Global objectives

The global objective of this restoration project was based on three goals:

• Restoration of 2km of the river in terms of physical features, flood management, habitat diversity, water quality, landscape and access for the community
• Application of innovative restoration techniques and best management practice within an urban environment
• The furthering of knowledge and understanding of river restoration by comprehensive monitoring and practical demonstration of the results to the local community and wider audiences.

Specific objectives

There were no specific goals for indicators in this project. Because it was the first project of its kind, the focus was more on achieving general social and ecological success.

Success Criteria

Because the focus of the project was more on achieving general social and ecological success, no strict success criteria for indicators were used.

Site description

Measures selection

To restore the Skerne in Darlington, several measures were taken. First, the channel was made more natural with meanders when there was enough space and a more natural river bank profile. The floodplain was lowered to create new shallow wetlands and more retention space, but also to make a natural flooding regime possible. The open outlets of the water system were changed to underground collection chambers to hide them from public view and to reduce the risk of pollution. To make the river accessible and attractive to the people of Darlington, new footpaths and recreational facilities are created in the new floodplains.

Monitoring

Pre-restoration monitoring Taken from The effects of river restoration on the R. Cole and R. Skerne demonstration sites: Final Report, River Restoration Centre March 1999. Please check full report for all details.

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

Ecology

River channel vegetation was monitored qualitatively by assessing the number of species found per 500 meter channel length. Aquatic macro-invertebrates were monitored by assessing the species richness. Fish were monitored by assessing the grams biomass per m2, fish density and species richness. Birds were monitored by assessing the assemblage of breeding birds and abundance.

Hydro-morphology

Geomorphological monitoring was carried out by mapping channel cross sections and physical habitat mapping. The water quality monitoring was focused on suspended sediment concentration and concentration of nitrogen (total oxidized nitrogen) and phosphorus (soluble reactive phosphorous) compounds. Measured at monthly intervals.

Flood protection

The hydrological regime was monitored by modelling the 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 questionnaire.

Post-restoration monitoring

The post-restoration monitoring consists of two methods. First, the same indicators and monitoring techniques used in the pre-restoration monitoring are repeated for post-restoration monitoring. The other method is comparing the data to another location, in this case downstream of the river. This was done to assess the impact of the restoration on the downstream areas, but it can also be used to compare the results of the restoration between the restored site and a control site.

The monitoring was planned for 1 year and 2 years after restoration. More long term monitoring was not planned due to lack of budget, but the project got the attention of the university world and later monitoring was done by Master and PhD students, for example between 2007 and 2009.

Expectations and Response

It was expected that the existing unpleasant park would improve in aesthetic quality and be more pleasant for the public as recreation area. The stream will feature more natural elements and the improved flooding regime will initiate more natural dynamics. The flood protection level remains unchanged, so the people of Darlington are still protected from flooding.

The full results can be found in the final report: The effects of river restoration on the R. Cole and R. Skerne demonstration sites: Final Report, River Restoration Centre March 1999. The results of later monitoring efforts are not yet published.

Ecology

Macrophyte species richness increased above pre-restoration levels with 30%, a year after restoration. The downstream control site did not seem to be affected by the restoration measures.

No changes were found in the macro-invertebrate community.

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 for 4 species. The appearance of new fish species can be related to the new fish pass below Darlington. Unfortunately, two severe pollution incidents occurred in 1997 and may have largely eliminated recolonizing fish populations.

Hydro-morphology

The river length was increased with 13%. Flood protection considerations required that the new channel cross-sections were maintained with similar proportions as the pre-restored channel. The river could not be restored to its original course with a natural channel cross section due to flood defence and services close to the channel (gas, electricity, sewerage). The water quality did not seem to be significantly changed after the restoration.

Flood protection

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.

Social-economic factors

The public had been engaged in the project since the planning phase and the post-restoration assessment showed that 52% of the Darlington 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.

Overall, the Skerne project was a big social success. People were engaged in the project and very positive about the end results. The ecological status has improved, but it is still restricted by the urban environment, for example fixation of the stream to protect gas line, and pollution from industry upstream.

Cooperation

The demonstration project in total was a collaboration between water managers in the UK and Denmark. However, the restoration itself was carried out by national, regional and local partners of both governmental and private sectors. The partners both worked on the river Cole and Skerne (Holmes et al., 1998). The project partners of the river Skerne were:

- National Rivers Authority (Environment Agency since 1996)

- English Nature (Natural England since 2006)

- Darlington Borough Council (landowner Skerne river)

- Countryside Commission

- Northumbrian Water

- Department of Agriculture N. Ireland (individuals, not entire organization)

- River Restoration Project (now River Restoration Centre)

- National Trust (landowner Cole river)

- Scottish Natural Heritage (individuals, not entire organization)

Communication

Communication with the public was an important part of the Skerne project and unique back in the day. The local residents were invited to give their opinion on the plans via the public perception surveys and were informed via leaflets, newsletters and public meetings during implementation. Their opinion was also an important part of the evaluation of the project success. Involving the landowner (Darlington Borough Council) as a project partner, further involved the voice of the community in the project.

Funding

The total budget of the project submitted to the EU-LIFE project was € 1,758,621.29, because Denmark was the leading partner. The UK budget was initially set at £850,000, but increased interest and support let the total project budget grow to almost £1 million.

The project budget for both the Skerne and Cole was divided in 4 elements, each with a set amount of budget. - £350,000 for construction contracts - £200,000 for pre- and post-restoration monitoring studies - £190,000 for management, promotion, compensations and administration - +/- £190,000 for survey, design, contract documentation and site supervision

The EU contribution to the total project was € 749,172.67.

Contact

River Restoration Centre

Dr. Ulrika Åberg

Tel.: 0044 1234 752979

Email: u.aberg@cranfield.ac.uk

Extra background information

http://www.therrc.co.uk/rrc_river_projects1.php?csid=37

This literature contains more information about river rehabilitation in general.

De Waal L.C., Large A.R.G. and Wade P.M. (eds) (1998) Rehabilitation of Rivers - Principles and Implementation John Wiley & Sons, Chichester (344pp)

Holmes N.T.H. (1998) A Review of River Rehabilitation in the UK 1990-1996 Environment Agency R&D Technical Report W175

Boon, P.J. and Raven, P.J. eds. (2012) Revisiting the Case for River Conservation, in River Conservation and Management, John Wiley & Sons, Ltd, Chichester, UK

References

Holmes, N.T.H., Nielsen, M.B., Vivash, R., Ottosen, O., Janes, M., Sørensen, H., Kronvang, B., Svendsen, L.M., Brookes, A., Fisher, K., Møller, B., Newson, M., Sear, D., Hoffmann, C.C., Pedersen, M.L., Øvig, L. (1998) Restoration of the Rivers Brede, Cole and Skerne: A joint Danish and British EU-LIFE demonstration project I – V, Aquatic Conservation: Marine and Freshwater Ecosystems 8:185 - 255

The effects of river restoration on the R. Cole and R. Skerne demonstration sites: Final Report, River Restoration Centre March 1999

Brochure River Cole, restored 1995/6, River Restoration Centre