Natural Flood Management

Working with Natural Processes

Concrete barriers and other “hard” defences, such as embankments, protecting homes from flood water are a common sight along rivers all over the country. 

However, they cost millions of pounds to build, often require expensive maintenance regimes and are never 100% guaranteed to work for every flood event, becoming less effective as our climate changes. In addition, protecting one location can also move the problem onto somewhere else, often the next house, village or town downstream. The “means or desire” to construct these forms of flood defence is also reliant on the level of flood risk within any particular location and the benefits which can be derived for such a high cost approach. 

There are other, more natural ways of reducing flood risk. These are based around how land and watercourses in the upper areas of a catchment is managed and form a core area of our work across both the Rivers Ouse and Adur. We have a wide range of experience in delivering effective schemes in both rural and urban settings and believe that co-creation, design and delivery with communities and landowners should be at the heart of these schemes. 

Natural Flood Management (NFM)

To reduce flood risk downstream, NFM incorporates a wide range of techniques. These include land management to store water both in soils and on the surface, altering surface water pathways and in-channel flow regimes to hold back and de-synchronize the flow of water across the landscape.  Our work shows that the right combination of measures, in the right place, backed by data, evidence and local knowledge can help to slow flood peaks and reduce the depth and duration of flooding. 

At the Ouse & Adur Rivers Trust our Project Officers have a wide range of experience in delivering landowner advice and working to ensure that any NFM scheme seeks to provide a range of wider benefits such as increased ecosystem resilience, improved water quality and soil health, drought resilience and community well-being. 

Adur Catchment NFM Project

Working in partnership with the Environment Agency, we received two years of funding from the Regional Flood and Coastal Committee (RFCC) to build an evidence based strategy to reduce the risk of flooding to properties risk across the Adur catchment. This encompasses the traditional approach to upstream interventions alongside the estuary and tidal sections of the river, assessing and mitigating the long term impacts which could result from climate change driven scenarios (e.g. rising sea levels, tidal surges etc).

To achieve our objectives and take this forward to delivering identified measures a committee of representatives from a range of stakeholders are assisting with building this vision for the future. These include Adur & Worthing Council, Horsham District Council, South Downs National Park Authority, Natural England, Sussex Inshore Fisheries and Conservation Authority (IFCA) and Sussex Wildlife Trust. 

Over the next two years (until 2023) our Natural Flood Management Officer will be liaising with landowners, local authorities and community groups to gain a greater understanding of the impact of heavy rainfall across the catchment and build a strategic approach to delivering interventions. This will include:

  • Supporting improvements to soil structure and the rebuilding of organic matter levels, focusing on where both overland and sub-surface flows are increased as a result of degraded soils and poor land management
  • Modifying flood banks to improve channel diversity, water holding capacity and/or re-connecting rivers with their floodplains.
  • Introducing leaky woody debris dams to slow the flow and create in-channel habitat, ensuring these continue to allow fish migration.
  • Introducing wetlands, ponds and scrapes as features in the floodplain to provide increased water storage.

 In addition to reducing the impact of heavy rainfall, this work will provide additional benefits including:

  • Reduced soil erosion and sedimentation loss to streams and rivers
  • Increased carbon capture and storage
  • Improved water quality
  • Re-connected rivers with species-rich floodplain wetlands
  • Creation of new habitat to help restore biological diversity. 

The project will establish the evidence required for future flood defence funds to be spent on solutions that are both cost effective and achieve wider benefits across the catchment. We strongly believe this is a far better option than building ever ever walls. 

For more information on the project or to find out how you can get involved contact

Hassocks Natural Flood Management

Since 2015 we have been working with HKD Transition to reduce the risk of flooding in the town of Hassocks. The aim was to reduce the amount of water reaching the small bridge culvert in the middle of the town which is regularly inundated, backing water up into upstream properties and reducing the effectiveness of surface water drainage.

During this period we have designed and implemented a number of schemes to reduce both in-channel flows, through the creation of a series of debris dams upstream of the bridge and surface water within the town itself. From rain gardens to small “planters” on downpipes the cumulative effect of these interventions has seen a reduction in water reaching the bridge and flooding has not occured during periods when it would be expected. 

We are continuing to work with the community and the HKD Floods & SuDS group to raise awareness of the issues and provide specialist advice on the solutions. 

Watch our video which explains more about the work being undertaken in Hassocks

Ouse Valley NFM

Working in partnership with Lewes District Council we have been designing and delivering NFM project across the District since 2016. Having been a partner on the  Our focus is currently on the villages of Ringmer and Wivelsfield as well as the Cuilfail community in Lewes itself. From urban wetlands to rain box planters, ponds and leaky dams to large scale river enhancements to re-connect the Ouse to it’s floodplain we are working across a large number of sites with the aim of protecting communities from flooding. 



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The Ouse & Adur Rivers Trust

OART is a membership based organisation dedicated to the environmental protection and enhancement of the Sussex River Ouse and Adur including their tributaries, estuaries and still waters.

The Ouse & Adur Rivers Trust (OART) is a registered charity (No: 1082447) formed in 2011 from the amalgamation of two long-standing local organisations, the River Adur Conservation Society and Sussex Ouse Conservation Society.

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