EA-NW-Walkhampton common runoff
Run-off was causing erosion damage in Walkhampton.
A pilot scheme aimed at using natural processes and less intrusive engineering techniques to reduce flood risk has been so successful it has secured funding to run until 2027.
The Dartmoor Headwaters project, a partnership between Dartmoor National Park and the Environment Agency, has been looking into ways flooding can be reduced in key areas.
It focused on five river catchment areas: the Mardle, the Dean Burn, the Collybrook, the Black Brook and the Hanger Down area of the River Erme.
These are upstream of communities such as Buckfastleigh, Peter Tavy, Walkhampton and Ivybridge, all of which have flooded in recent years, posing risks to homes and businesses.
The project was funded by the Environment Agency through the Flood Defence Grant in Aid from 2018 until 2021.
Outcomes so far include:
- Planting 6,000 trees on enclosed land across the National Park
- Rewetting meadows and improving biodiversity
- Lane drainage improvements at Scorriton
- Installing natural dams at places like Dean Moor and Holne Moor to prevent water run-off
- Reconnecting flood plains to ‘hold’ water
- Improving public rights of way damaged by water erosion
- Supported peatland restoration, 35ha of which was completed on Holne Moor during Spring 2021.
Dartmoor Headwaters brings together a range of organisations and individuals including experts in soil management, ecology, forestry, archaeology, engineering, landowners, commoners and residents.
Detailed survey work on archaeology, soil, hydrology and habitats have been conducted to ensure the solutions are appropriate for each particular environment. These include naturally leaky barriers made from wood, stone, willow, wool and fallen timber; re-wiggling rivers, wetland improvements, tree planting and dealing with flood water on eroded public rights of way.
Headwaters Project Officer Kerry Smith said: ‘We’re really pleased to have secured funding to build on the work already achieved. The measures we’ve carried out are less intrusive than more traditional flood defences and can bring added environmental benefits.
‘This work has never been more timely, with many reminders this year of our responsibility to look after the environment and of the climate and biodiversity emergencies we are facing. Natural disasters such as fire, drought, floods and loss of species are becoming increasingly frequent and are set to increase if positive change is not made.’
Natural Flood Management is all about trying to slow down and store water high up in the catchment near to the source of the river, to reduce the risk of flooding to communities downstream. The techniques used are more suited to the Dartmoor landscape than the more traditional flood barriers and storage reservoirs we are used to seeing. They are relatively small interventions but it is the sum of many across a catchment that can make the difference to peak flows. They can be used where more engineered solutions exist downstream to provide a higher level of flood resilience for longer and to take account of climate change increasing river flows over time. This approach enhances biodiversity, increases carbon dioxide capture and storage and improves water quality.
The Natural Flood Management project has contributed funding towards 70ha of peatland restoration, vital work in the current climate crisis, 35ha of which was completed on Holne Moor during Spring 2021; a further 35ha will take place on Buckfastleigh Moor this autumn. Restoring degraded peatland restores the natural hydrology and re-establishes a Sphagnum moss layer. This provides the long-term stability peat needs to re-start peat formation and carbon sequestering processes, necessary to store water and carbon.
During the pilot phase of the project, work to slow down moorland run-off was carried out on an area of Walkhampton Common. Run-off was causing erosion damage and flowing at speed as it headed down through farmland towards Walkhampton, which has flooded in recent years.
A series of stone dams were installed on flow pathways on the common to slow down water and water was impeded in gullies around archaeological features at risk of water damage. Further intervention was needed where the water left the common entering a yard area, by diverting water away from cattle feeding and loafing areas and creating bunded areas to intercept the water. Trees were planted to help with water infiltration, screening and biodiversity. Work around Walkhampton was hampered by Covid 19 and will continue into the current phase of the NFM project.
Rob Newton of the Environment Agency said: ‘We are proud to be working with Dartmoor National Park Authority, the community, landowners, stakeholders and partners to investigate natural flood management techniques on Dartmoor.
‘We have made good progress during the pilot over the last four years particularly with regards to exploring, learning, and trialling how best to work within river catchments to reduce flood risk downstream and improve the environment. We are looking forward to building on the partnership’s successes and implementing the techniques in phase two of the project.’
The work has also provided ecological benefits; run-off water diverted into meadows, for example, reduces the volume of run-off and helped by a series of ponds and scrapes, can attract dragonflies, damselflies and other insects.
The learning so far has helped secure further funding to extend this important work into the next phase and demonstrates how working together can result in good outcomes for the environment.
Kerry added: ‘The Dartmoor Headwaters Project is keen to work with farmers, landowners and commoners within the National Park who have NFM project proposals, especially those working in collaboration with neighbours or on commons, where we can influence flood risk and benefit the environment on a greater scale.’
The project is supported with contributions from partners including Highways England, Plymouth University, Devon County Council, Devon Wildlife Trust, Moor Trees, West Country Rivers Trust, Forestry England and Natural England.
For more information please contact the Dartmoor Headwaters Project Officer Kerry Smith on 07849 085339 / ksmith@dartmoor.gov.uk or contact the NFM mailbox on dartmoornfm@environment-agency.gov.uk