Surface water flooding is a growing risk to the UK, particularly from summer thunderstorms. Dr Steven Cole, a hydrological modeller at the UK Centre for Ecology & Hydrology, explains how our research and models are helping advance the forecasting of these events…
In England, the new National Flood Risk Assessment (NaFRA) now estimates around 4.6 million properties are currently at risk from surface water flooding. Summer rainfall is also predicted to become more intense under climate change, creating even greater risk to life.
The emerging scale of surface water flood risk was first recognised almost 20 years ago by analysing the devastating 2007 summer floods. This showed that two-thirds of the 55,000 affected properties suffered surface water flooding – which was unusually high.
UKCEH contributed to the subsequent government Pitt Review and has been helping deliver the report’s recommendation of effective surface water flood forecasting, which was not done previously.
The aim is to provide county-level forecasts of surface water flooding risk, which enables local authorities to take action, for example check and clear drains, provide early warnings to the public so they can protect property and belongings, and prepare emergency response.
There has, therefore, been a move by researchers to impact-based forecasting, where not only the hazard (eg flooding) is forecast but also the potential impact on lives and livelihoods. This requires a wide range of expertise and was taken forward under the Natural Hazards Partnership that UKCEH co-founded in 2011.
Showcase of latest research
UKCEH has contributed expertise to the partnership through use of the Grid-to-Grid (G2G) hydrological model, which produces forecasts of surface water flooding across the whole of England and Wales. The Met Office has provided rainfall forecasts and computing infrastructure while the Health and Safety Executive developed the impact assessment approaches.
This collaborative research has been brought together to develop a Surface Water Flooding Hazard Impact Model which informs the daily Flood Guidance Statement for England and Wales which is used by emergency responders and government agencies. The statement is produced by the Flood Forecasting Centre (FFC), a joint initiative between the Environment Agency and the Met Office.
On 24 April, at the FFC’s offices at the Met Office HQ in Exeter, it hosted a showcase of the latest advances in surface water flooding for scientists, forecasters and policymakers.
This included updates on technical improvements in forecasting, with UKCEH scientists sharing the latest developments on the hazard impact model. Perhaps most importantly, it also showed how the improved forecasting is helping the emergency response community make better decisions.
The showcase marked the end of the three-year phrase of the Surface Water Flood Forecasting Improvement Project (SWIPP), which is overseen by Defra and the Environment Agency. Going forward, UKCEH will support FFC on the next three-year programme to continue to advance surface water flood forecasting.