2.15. River Restoration Flashcards
What does river restoration involve?
Involves removing all hard engineering adaptations to restore meanders, wetlands and floodplains. The aim is to return drainage and therefore flood management back to nature
What happened in the 1900s to the River Skerne?
It was straightened and channelised to accommodate industrialisation and urbanisation.
As the population grew and new housing estates were built, the Skerne was widened and deepened to improve drainage.
What happened in the 1990s to the River Skerne?
A 2km stretch of the river was returned to nature -> this is an example of river restoration and conservation in a damaged urban catchment
Where is the River Skerne located?
- Upstream of Darlington
- A tributary of the River Tees in north-east England
Historically, how has the urban catchment area been damaged?
- Between 1850 and 1945, the river was straightened and channelised to accommodate industrialisation and urbanisation
- Subsequent widening and deepening was undertaken in the 1950s and 1970s to further improve draining and reduce flood risk; new housing developments were built along the entire north side of the river
- Deindustrialisation has left polluted wasteland
- Heavily engineered river
What are the aims of the project?
- 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 by practical demonstration of the results to the local community and wider audience
What did the project involve?
- A project adopting the use of soft revetments, such as willow mattresses, on the outer banks of the restored meanders to protect the pipelines from erosion was initiated in July 1995
Who was involved?
- Local communities
- River Restoration Project
- Environmental agency
- Darlington Borough Council
How has the restoration improved water movement through the urban catchment?
- Velocity has been slowed as meanders have been restored
- Slowed down runoff as friction has increased or more infiltration opportunities
- Increased the length so increased channel capacity so more channel storage
- Greater interception from tree and shrub planting
- Increased storage by lowering the floodplain, by creating backwater and wetland and vegetation storage
What challenges did the planners have to overcome to make the project successful?
- Existing infrastructure -> gas, sewer pipes, electric cables restricted how far they could restore the river
- Built environment -> houses already there
Re-meandering
4 meanders were reinstated
Re-meandering the course where space permitted, cutting a new channel and filling the old
Lowering of fooodplains
Store water in times of high flow
Slows run off
Backwaters and wetlands
Increased water storage
In high flows, they provide shelters for fish, especially the young. Wetland areas attract other species of plants and animals, including young dragonflies and damselflies which feed over wildflower grasslands
Revetments
Where remeandering was possible, it was necessary to protect the north bank from erosion and potential exposure of gas main
Natural techniques used -> ready planted coconut fibre rolls + willow trees use ability of living plants roots to bind earth bank and form protective cover
Landscaping and planting
To allow river to overspill to meandering banks but still protect surrounding houses, the floodplain was lowered by moving 20,000m cubed of soil. This soil was used to reshape bare valley sides at Rockwell and screen the view of local industry at the keepsafe. With help from local schools, each area was planted with 20,000 trees and shrubs + bulbs and flowers
Increases interception, improve environment and habitats
