How can we protect UK rural communities at risk of flooding?
As global temperatures rise, extreme rainfall and flash flooding are set to increase, putting more homes and livelihoods at risk. With rural communities near steep upland streams and rivers particularly vulnerable, research at The University of Manchester is demonstrating that landscape restoration offers a low-cost way to reduce flood risk.
Protect-NFM provides evidence for how upland restoration can contribute to natural flood management (NFM), and how restoration methods can be optimised to help protect 22 at-risk communities in the Peak District, along the western fringe of the Pennines.
Protecting vulnerable communities
Small rural communities in the UK are particularly vulnerable to flash flooding because they rarely justify expensive traditional flood defences; the focus has to shift upstream to the source of rivers.
Many of these rural communities sit at the bottom of catchments covered by blanket bog that has been damaged through a combination of pollution, fire, unsympathetic management and climate change. These pressures have killed vegetation and caused widespread erosion, which means water flows off the landscape very quickly, contributing to flooding downstream.
The project is improving our understanding of how to dam up erosional channels (gullies), studying the impact of restoring Sphagnum moss cover on moorlands, and determining how newly-planted upland woodlands affect storm flow. It is also assessing the longer-term evolution of woodland and gully blocking approaches; this is important because investment in NFM requires confidence in the long-term impact of restoration and maintenance of the interventions.
Restoration and reintroduction
The team has shown that upland restoration can have a substantial impact on the flow of water during storms. Reintroducing vegetation to bare soils and damming up erosional channels increases the roughness of the land's surface and slows the flow of water entering streams. This delays the release of water from the uplands and reduces peak streamflow during storms, alleviating the chance of flooding downstream.
Crucially, this NFM benefit is not at odds with other aims of restoration (such as raising water tables to make bogs wetter), as the effect is linked to surface roughness slowing the flow of water, rather than storing water below the surface when it rains.
Ongoing work demonstrates that plant-type is also important. Initial restoration methods involve planting grass (like that found on lawns) because it grows quickly and stabilises eroding surfaces. Over time this dies back and more natural moorland plants return.
Further restoration accelerates the return to more natual conditions by planting sphagnum moss; a keystone species essential for healthy bog function and growth. The team found this "super moss" further slows the flow of water, providing more NFM benefits from restored upland bogs.
The project is led by researchers from Manchester's Department of Geography, alongside colleagues at the University of Leeds, Newcastle University, project partners Moors for the Future Partnership, and the Greater Manchester, Merseyside and Cheshire Environment Agency.
Protect-NFM is one of three projects funded through the Natural Environment Research Council (NERC) Understanding the Effectiveness of Natural Flood Management programme, and will be presenting findings at the programme wrap-up event in summer 2022. The team will also visit local flood groups in communities at risk of flooding around Manchester, informing them of the findings and how this could help reduce their flood risk.
Professor Martin Evans
Professor Evans is a Professor of Geomorphology and Head of the School of Environment, Education and Development.
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Dr Emma Shuttleworth
Dr Shuttleworth is a Lecturer in Physical Geography.
View Dr Shuttleworth's research profile
Professor Tim Allott
Professor Allott is a Professor of Physical Geography.
View Professor Allott's research profile
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