Improving early warnings for flash floods
Climate change is increasing the risk of flooding across the globe, with devastating effects. Advanced warning can reduce flood impacts, but it requires localised, accurate and reliable forecasts.
Professor Cathryn Birch and her research team developed, tested, and evaluated a new flood forecasting tool that improves early warning information for flood responders—that could also be used anywhere in the world.
Watch the video summary
Impact
- Knowledge discovery: developed, tested and evaluated a new flood forecasting tool
- Policy impact: provided a tool for the Met Office, Environment Agency, Defra, and Scottish Environment Protection Agency to improve their national flood forecast services; helped to shape Defra’s Surface Water Flooding Action Plan.
- Economic and environmental impact: improved flood response will improve the UK’s resilience to flood risk – preventing loss of life and reducing damage to homes, businesses, and infrastructure.
Key information
- Major funders: UK Research and Innovation (UKRI),
- Partners and collaborators: Yorkshire Integrated Catchment Solution Programme (iCASP), Flood Forecasting Centre, Met Office
- Disciplines: earth and environment, extreme weather, forecasting
- Investigators: Professor Cathryn Birch.
Flash floods are difficult to predict
Flooding severely impacts society, the economy, and national security through loss of life and damage to property and infrastructure.
In the UK, flooding is categorised as coastal, river, or flash flooding. Flash flooding is flooding that occurs before rainfall reaches a major watercourse, often referred to as surface water flooding in the UK. Climate change is increasing the risk of all these types, making early warning systems essential for the country’s climate resilience.
Flash floods rise quickly and can be fast flowing, with high impact in urban areas due to the density of people and infrastructure.
People don’t always know about flash flood risks because they can happen far away from watercourses and in areas that haven’t flooded before.
The rainfall that causes flash flooding is often intense, short-lived and highly localised, so it's very difficult to accurately forecast and communicate the uncertainties.
Alongside project partners at the UK Met Office, Flood Forecasting Centre, JBA Consulting and University of Oxford, Leeds researchers investigated how to better predict flash floods.
They were supported by the UKRI-funded Yorkshire Integrated Catchment Solution Programme (iCASP), led by the University of Leeds.
The team developed, tested and evaluated a new flood forecasting tool called FOREWARNS: Flood fOREcasts for Surface WAter at a RegioNal Scale. It will soon be run in real-time by the national Flood Forecasting Centre and Met Office to aid flood forecasters in producing warnings, but could also be applied anywhere in the world.
Public and civic engagement
FOREWARNS uses probabilistic rainfall forecasts, post-processes them to allow for uncertainties, and links the rainfall rates to pre-computed flood thresholds.
The forecasts are presented on a map of England and Wales for each river catchment as a reasonable worst-case flood scenario. The tool can be set up to predict days or hours in advance of a flood.
To develop the tool, the team first engaged with local authorities, emergency services, flood wardens, and flood forecasters to understand their existing flash flooding processes and tools.
They found that there was a lot of uncertainty in existing flood forecasts, and a lack of detailed, reliable information, which meant that the flood responders were generally unable to act in advance of a flood.
This motivated the team to produce an early version of the forecast tool, which was tested with flood responders in a game-play event simulation workshop co-organised by the Leeds team and JBA Consulting.
FOREWARNS was updated based on users’ feedback and tested again through a co-production workshop at the University of Leeds and two ‘testbed’ events in the summers of 2023 and 2024 with the Met Office and Flood Forecasting Centre.
Results from the testbed showed that forecasters valued using FOREWARNS in their operational forecast and warning production process because it produces a low number of false alarms and combines multiple sources of information into a single map.
Professor Birch said: “I realised through this work that flood responders often do not know where floods have occurred until visual reports from staff or the public come in.
“I am really proud to have produced a tool that will soon be part of the national capability in flood forecasting, assisting forecasters in issuing improved flood guidance.
“The next step for me is to work with satellite experts at University of Leeds and SatSENSE to develop a way of observing, mapping and monitoring major flood events in near real time, another major gap in current national capability.”
In recent months she has worked with SatSENSE – a University of Leeds spin-out – to find a way to identify floods from Sentinel satellites that can be applied rapidly to the whole of the UK and provide country-wide flood maps during major flood events for monitoring and response.
An example forecast with hatched areas where flooding occurred
Shaping flood action and policy
FOREWARNS and its associated research helped to shape Defra’s Surface Water Flooding Action Plan.
The research provided a tool for the Met Office, Environment Agency, Defra, and Scottish Environment Protection Agency to improve their national flood forecast services.
Graeme Boyce, Flood Forecasting Centre’s (FFC) Strategy and Development Coordinator, said: “In response to Defra’s Surface Water Management Action Plan, the Environment Agency and Met Office are scoping a new capability for sharing with responders very short range and rapid update forecasting (“nowcasting”) for the type of rainfall that causes surface water flooding.
“FOREWARN team’s final report, including feedback from the incident response workshop, has provided valuable information and user response insight for the discovery phase of this project and we expect that continued engagement with the iCASP team will continue to be beneficial for understanding user needs and exploring piloting opportunities.”
When FOREWARNS is up and running operationally at the Met Office, it will have a nationwide impact.
More than 40 forecasters will have access to improved flood forecast information that automatically combines a number of information sources, saving time and improving forecaster confidence in their decisions.
FOREWARNS will be used by flood forecasters to produce the Flood Guidance Statement and Rapid Flood Guidance that is issued to 100’s of flood responders across the country.
The FOREWARNS tool is freely available via a computer code repository and would be straightforward for any National Weather Service to download and run over their own country.
Improved flood response will ultimately improve the nation’s resilience to flood risk and have far-reaching benefits to society – preventing loss of life and reducing damage to homes, businesses, and infrastructure.
About Professor Cathryn Birch
Cathryn Birch is a Professor of Meteorology and Climate in the School of Earth, Environment and Sustainability.
She researches the causes of weather and climate extremes to improve weather forecasts, climate projections and Early Warning Systems.
Prior to her academic position, Cathryn worked as a Senior Scientist at the Met Office and has continued to collaborate closely with them on a wide range of projects.
Her recent awards include:
- 2024: Emerging Environmental Impact Award for improving national early warning capability for flooding, University of Leeds Research Impact and Engagement Awards
- 2021: University of Leeds Queen’s Anniversary Prize, part of the team that conducted the research that empowered tropical communities to face the challenges of extreme weather
- 2020: Water@Leeds Water Woman Award for Research Funding Excellence.