Natural mitigation of flood risk
The UK’s flood risk from rivers, surface water and ground-water is projected to increase with climate change. Natural flood management (NFM) can be described as using the natural features of the land to store and slow down the flow of water. NFM is being piloted across the UK and its expansion is an objective of the Government’s 25 Year Environment Plan. This POSTnote examines the evidence for the effectiveness of NFM at reducing flood risk, and successful governance approaches to implementing NFM measures.
DOI: https://doi.org/10.58248/PN623
The UK Government's 2017 Climate Change Risk Assessment report identified increased flood risk as one of the UK's top climate change risks. In some areas, peak flows (the maximum flow of water at a given point in a river during a flood event) have been increasing at a rate of over 5% per decade. The winter of 2019/20 saw extensive flooding caused by Storms Ciara and Dennis in parts of the UK during the wettest February on record, and a record-breaking number of Environment Agency flood warnings were issued. The UK's vulnerability and exposure to flood risk continues to grow; approximately 10% of new homes are built in high flood risk areas, and over 500 major infrastructure assets are vulnerable to flooding.
NFM is an approach to managing flood risk that aims to create, restore or alter landscape features to reduce flooding. It has been highlighted as an important flood mitigation strategy in the 2018 National Infrastructure Assessment and the 2019 draft National Flood and Coastal Erosion Risk Management Strategy for England. The Government’s 25 Year Environment Plan also aims to expand use of NFM, setting out £15 million of investment into research and implementation between 2018–2021. Measures are currently being applied or considered in over 236 areas throughout the UK.
Key points in this POSTnote include:
- NFM can help mitigate the impacts of smaller, more frequent floods and can be a low-cost option for helping to manage flood risk for smaller communities.
- However, as it is not yet proven to mitigate the impacts of extreme flooding or flooding in large catchments, NFM should be used in conjunction with built flood infrastructure.
- NFM delivers many environmental co-benefits, such as carbon storage, water quality protection and biodiversity enhancement, allowing environmental objectives to be addressed simultaneously.
- Successfully implementing NFM requires working in complex multi-stakeholder partnerships, with local communities and land managers participating in decisions.
- Barriers to the implementation of NFM include a lack of public awareness, administrative barriers, and insufficient long-term incentives for land managers.
Acknowledgements
POSTnotes are based on literature reviews and interviews with a range of stakeholders and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:
Lydia Burgess Gamble, Environment Agency*
Chris Uttley, Environment Agency*
Jonathan Simm, HR Wallingford*
Rob Collins, The Rivers Trust
Paul Cobbing, National Flood Forum
Alison Fergusson, Ofwat*
Sharma Jencitis, United Utilities
Brendan Freeman, Committee on Climate Change
Professor Simon Dadson, University of Oxford/CEH*
Dr Chris Short, University of Gloucestershire*
Kirsty Holstead, University of St Andrews*
Dr Nick Chappell, University of Lancaster/ President of UK Hydrological Society*
Professor Martin Evans, University of Manchester
Mhari Barnes, NFU
Stewart Clarke, National Trust
Dr Tom Nisbet, Forest Research*
Barry Hankin, JBA*
Professor Joanna Clark, University of Reading
*Denotes people who also acted as external reviewers of the briefing