Working with natural processes to reduce flood risk 2024
Source: gov.uk (2025-02-12)

The evidence base for working with natural processes to reduce flood risk

This page contains the research report and literature review for the 2024 ‘Working with natural processes evidence directory’.

An overview of the evidence for each measure is available on the summaries page (https://www.gov.uk/government/publications/natural-flood-management-evidence).

Documents

Research report (https://assets.publishing.service.gov.uk/media/67c6e14c68a61757838d2265/FRS21232_Research_report.pdf) - provides an overview of the evidence on the measures.

Literature review (https://assets.publishing.service.gov.uk/media/67a094721d14e76535afb6c0/FRS21232_Literature_review.pdf) - provides detailed referenced content with information around specific studies.

Summaries (separate page) (https://www.gov.uk/government/publications/natural-flood-management-evidence) - includes quick guides for each of the measures covered in the directory.

Summary

Working with natural processes (WWNP) aims to protect, restore and emulate the natural functions of catchments, floodplains, rivers and the coast to reduce flood risk. It is also referred to as natural flood management (NFM).

We published the ‘Working with natural processes evidence directory’ in 2017 (https://www.gov.uk/flood-and-coastal-erosion-risk-management-research-reports/working-with-natural-processes-to-reduce-flood-risk).

This update brings together evidence from natural flood management studies published after 2017. It tells us where knowledge has improved or changed since the original evidence directory was published.

Approach

As far as possible, the same scope and structure of the original evidence directory was kept. Some changes were made to reflect the advances in the science and practice of working with natural processes.

The scope of this update includes:
- academic and grey literature
- literature from 2017 to 2023
- studies focusing on all points of the project lifecycle (e.g. modelling and design through to implementation, effectiveness and monitoring)
- international studies where the climatic context is similar to the UK
This review was consistent with the approach adopted in the 2017 edition and sought to balance a broad search of the literature with the use of expert knowledge. Whilst the search may not be fully exhaustive, it reflects the evidence base available which is more developed in some areas than others. Some research may have been missed due to the nature of the search process and the prevalence of unpublished supporting evidence.

The updated research report is a summary of the original findings from 2017, new evidence, our confidence in the evidence and remaining research gaps. The report signposts readers to the relevant parts of the literature review for more detailed information.

The measures covered are:
- river restoration
- floodplain/wetland restoration
- leaky barriers
- beavers
- offline storage areas
- catchment woodland
- cross-slope woodland
- floodplain woodland
- riparian woodland
- soil and land management
- headwater drainage management
- run-off pathway management
- saltmarsh and mudflat management
- beach nourishment
- sand dune management
- reefs
- submerged aquatic vegetation (SAV) and kelp
A key addition to the 2024 evidence directory is the inclusion of beavers, reefs and submerged aquatic vegetation as additional WWNP measures. This is due to the increase in evidence in a UK context since 2017.

A new chapter on “cross-cutting” NFM seeks to provide a summary of the evidence where multiple types of NFM have been implemented in one catchment.

The following elements from the 2017 version have not been updated:
- guidance on project monitoring
- Working with Natural Processes – Using the evidence base to make the case for Natural Flood Management
- mapping the potential for WWNP
- appendix 1. Using flood risk evidence to make the case for Working with Natural Processes – the flood risk matrix
- case studies
Findings

We found:
- general agreement across new literature that NFM can reduce flood risk and has wider benefits
- new evidence for all measures, but the volume varies
- our broad understanding of NFM has improved but specific gaps remain
Webinar

The project team held a webinar about the findings on 19 March 2025.

Webinar - Working with natural processes evidence directory (https://youtu.be/Jk1fByvxF-o)

Project Information

Project manager: Daniel Hine

This project was commissioned by the Environment Agency’s FCRM Directorate, as part of the joint Flood and Coastal Erosion Risk Management Research and Development Programme.

A Welsh translation of the summary is also available. (https://assets.publishing.service.gov.uk/media/67c6e2e8b0bb6528ee866db0/FCRM_research_GOV.UK_summary_page_-_FRS21232_Welsh.pdf)