Nature-based solutions: Natural flood protection

Protecting Leeds from rising river levels

Leeds is in a catchment where river levels can rise rapidly in response to rainfall and there is rising risk of fluvial flooding. To protect the city and its almost 800,000 residents, the council and Environment Agency are combining traditional engineering methods and natural flood management (NFM) to improve defences and build resilience. The project will introduce NFM across the 700km2 of the River Aire catchment, from Armley, west of the city centre, to Malham in the Yorkshire Dales. It is the largest NFM project in the UK.

Nature-based interventions for flood risk reduction

As part of our work to identify and deliver the most appropriate and effective NFM schemes across the catchment, we’ve developed a suite of innovative geographic information system (GIS) tools to provide a consistent approach. We also created a risk-based leaky barrier tool to help pinpoint the best locations for installation as well as a Woodland Carbon Code tool to estimate carbon sequestration from the creation of woodland.

Our nature-based interventions have been tested at several pilot sites. These include:

• detailed designs to reduce flood risk and maximise opportunities to enhance the environment – including swales, bunds, leaky barriers and ponds – at Marlfield Farm
• linking NFM, rewilding and wellbeing in line with the landowner’s vision for an estate covering more than 16km2 in the Upper Aire region
• an NFM concept design – including planting almost 4000 trees and hedges, and creating wetland scrapes (shallow ponds) to control stormwater – at Bodington Playing Fields, part of the University of Leeds, to showcase natural solutions, improve stakeholder engagement and provide opportunities for academic research to enhance our understanding of the multiple benefits of these nature-based solutions

Enhancing biodiversity and community benefits

Our systematic, repeatable and auditable process for managing the development and delivery of NFM solutions will be used at hundreds of sites across the catchment. Key to its success is our GIS platform, which will facilitate the advance of a pipeline of sites and lead users through from feasibility to concept design, and then delivery and ongoing management of the assets.

Millions of new trees and other vegetation will be planted to capture and store carbon, promote biodiversity and create new habitat as well as intercept and slow the flow of rainwater into the River Aire. Runoff pathway management, and river and floodplain management interventions, such as leaky barriers, will also be implemented to store and slow the flow of water in the uplands.

Overall, NFM will improve the climate resilience of the city of Leeds and other communities throughout the catchment as well as deliver a range of wider benefits for people and nature.