Natural Flood Management: Harnessing Nature to Mitigate Flood Risks

Progressively wetter winters and localised heavy rainfall has repeatedly overcharged our river catchments and inundated our communities in recent years. Our last blog on Storm Bert in November 2024, clearly demonstrated how fragile and vulnerable we are in the face of limited funding to maintain and reinforce our flood resilience infrastructure through traditional means. Government flood management investment, often reacting to events rather than in anticipation of them, has tended to focus on hard flood defences – channelling water faster elsewhere.

In the 1970s and 1980s, many of Britain’s rivers and streams were being “improved” – straightening out meanders, dredging river beds and removing vegetation from the banks so that the water could flow more easily. At the same time, agriculture has become more intensive, requiring more space and clearing more upland catchments for grazing. A massive increase of drainage of farmland in river catchments means water now gushes off land straight into the rivers.

But there are more natural, potentially far cheaper and more sustainable ways to manage flood risk.

Natural flood management (NFM) is gaining prominence as a better answer to reducing flood risks. By utilizing natural processes to slow down and store water, NFM not only mitigates the impacts of flooding but also enhances ecosystems, supports biodiversity, and provides additional benefits such as improved water quality and carbon sequestration. This blog explores key examples of NFM in action, including the pioneering efforts in Pickering, North Yorkshire, and the surprising role of beavers in flood management.

Pickering, North Yorkshire: “Slow the Flow”

Pickering, a market town in North Yorkshire, has faced repeated flooding over the years and is particularly at risk from summer flash floods due to the steep nature of the catchment.Conventional flood defenses were deemed unsuitable due to financial and technical constraints. Instead, a groundbreaking NFM project called “Slow the Flow” was implemented in the 2010s, showcasing how nature-based solutions can effectively mitigate flood risks. Led by Forest Research, this pioneering approach to flood management relied on making changes to the way the landscape is managed, so that the passage of rainfall to rivers and its movement downstream is reduced and delayed.

Measures Implemented

The Pickering project employed several NFM techniques:

1. Woody Debris Dams: Over 150 leaky wooden dams, also known as “leaky barriers,” were constructed in upland streams. These dams slow the flow of water during heavy rainfall, reducing the peak flow downstream.
2. Tree Planting: Thousands of trees were planted to increase water infiltration and reduce surface runoff. Forested areas also act as natural sponges, holding water and releasing it slowly over time.
3. Offline Storage Areas: Large storage basins were created to temporarily hold excess water during storms, preventing it from overwhelming the town’s drainage systems.
4. Soil Management: Measures to improve soil structure, such as reduced compaction and planting cover crops, were introduced to enhance water infiltration and reduce surface runoff.

Results

The project was a resounding success, significantly reducing flood risk in Pickering. One of its first major tests came with the major flooding of 2015 which affected large parts of Yorkshire. The measures implemented were demonstrably proven to have prevented flooding, protected properties and community assets, such as the museum, that would have ordinarily been swamped – and reduced the flood peaks by between 15 and 20%. Half of this reduction came from upstream land management measures, with the rest from the main flood storage area within the excess storage basins.

It provided a proof-of-concept for NFM, demonstrating that small, cost-effective interventions can collectively make a substantial impact. The “Slow the Flow” initiative also inspired similar projects across the UK and beyond.

Beavers: Nature’s Engineers

Beavers, once extinct in many parts of the UK, are making a comeback and playing an unexpected role in flood management. These industrious rodents are known for their dam-building activities, which create wetland habitats and regulate water flow.

How Beavers Help

Beaver dams are natural leaky barriers that:

1. Slow Water Flow: The dams reduce the velocity of water, particularly during heavy rainfall, thereby lowering downstream flood peaks.
2. Increase Water Storage: The ponds and wetlands created by beavers act as natural reservoirs, storing water and releasing it gradually over time.
3. Enhance Groundwater Recharge: Beavers’ activities increase water infiltration into the soil, replenishing groundwater reserves.
4. Improve Biodiversity: The wetlands created by beaver dams support a wide range of plant and animal species, enhancing ecosystem resilience.

Case Study: Devon Beaver Project

In Devon, a trial reintroduction of beavers along the River Otter has provided valuable insights into their role in NFM. The trial ran from 2015 to 2020 and revealed that beaver dams reduced peak flows by up to 30% during heavy rainfall events. It was the first trial of its kind in the country and enabled the beavers to roam freely to create the habitats naturally where they wanted, without being penned in. Additionally, the wetlands created by beavers improved water quality by trapping sediments and nutrients.

Thanks to the success of the project, in 2020 DEFRA agreed to allow the beavers to migrate into other river catchments, expanding their population and effectiveness. Some concerns have been expressed by farmers about the loss of vegetation cover, including some riparian planting, but the results speak for themselves.

Additional Examples of NFM

While Pickering and beavers are standout examples, numerous other NFM projects across the UK and globally illustrate the potential of nature-based solutions:

1. Peatland Restoration: Restoring degraded peatlands in upland areas helps to store water, reduce runoff, and sequester carbon. Projects in the Pennines and Scotland have shown promising results in reducing downstream flooding.
2. Rewilding Rivers: Removing artificial barriers and allowing rivers to meander naturally increases their capacity to store water during floods. The River Wandle in London is a notable example of river rewilding enhancing flood resilience.
3. Wetland Creation: Constructed wetlands in flood-prone areas, such as the Wallasea Island Wild Coast Project in Essex, not only reduce flood risks but also provide valuable habitats for wildlife.
4. Urban Greening: In cities, green roofs, rain gardens, and permeable pavements reduce surface runoff and alleviate pressure on drainage systems. Schemes in Sheffield and Manchester demonstrate the benefits of urban NFM interventions.

Challenges and Opportunities

While NFM offers numerous benefits, it is not without challenges. One key issue is the scale required to achieve meaningful flood risk reduction. Implementing NFM across large catchments often requires collaboration among multiple stakeholders, including landowners, local authorities, and conservation groups. But the appetite to proceed is mixed.

A study published by the British Ecological Society in 2022 identified that farmers are turning to rewilding to create new sources of income and diversify their farming practices. Farming in tandem with nature can be productive, especially in organic systems. However, some are concerned that rewilding initiatives could put food security at risk. They worry that the government is too focused on restoring agricultural land to its natural state, without considering the impact on crops and livestock.

A key part of this is the incentives available for farmers to set aside land for riparian planting, creation of natural dams and peat restoration. Countryside Stewardship Grants are in place to support, but alongside Rewilding Grants, offer often small scale investment not at the level of former EU “set aside” policies to create natural spaces on less productive land.

However, the opportunities are immense. NFM aligns with broader environmental goals, such as combating climate change and enhancing biodiversity. Public awareness and support for NFM are growing, bolstered by successful projects like Pickering and the Devon Beaver Project.

Conclusion

Natural flood management represents a paradigm shift in how we approach flood risk. By working with nature rather than against it, NFM provides sustainable, cost-effective, and multifunctional solutions. The examples of Pickering and beavers underscore the potential of nature-based approaches to reduce flood risks while delivering a host of co-benefits. As climate change intensifies the frequency and severity of flooding, embracing NFM will be crucial for building resilient communities and ecosystems.

References

https://www.forestresearch.gov.uk/research/slowing-the-flow-at-pickering

https://www.devonwildlifetrust.org/what-we-do/our-projects/river-otter-beaver-trial

https://www.rochford.gov.uk/wallasea-wetlands-project

https://www.wildsheffield.com/wp-content/uploads/2022/04/210701-Urban-greening-in-Sheffield.pdf

https://www.manchesterclimate.com/zerocarbon/urban-greening

https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/pan3.10376#

https://www.gov.uk/countryside-stewardship-grants

https://www.rewildingbritain.org.uk/how-to-rewild/funding-for-rewilding/rewilding-innovation-fund