Hull flood risk model to aid global climate change planning

WORLD FIRST: The new flood risk map of Hull. Picture credit: University of Cambridge

By Angus Young

A ground-breaking flood risk modelling tool developed for Hull is set to help tackle the challenge of climate change around the world.

Researchers behind the project say it can equally be applied to other towns, cities, regions and even small countries in early decision-making about how to deal with rising sea levels.

For Hull, they mapped the city into 1,000 separate, 400 metre-wide virtual hexagons to chart multiple computer-simulated flooding scenarios and combine data on the likely economic impact on homes, schools and businesses in each area.

The digital tool allowed them to dramatically condense around ten million separate pieces of data covering 21,300 scenarios resulting from 122 different sea-level rises and seven extreme flooding events – including overtopping of defences and floodwater spreading across land – into just two hours of processing.

Developed as a web-based portal, the work in Hull is the first time the full scope of the Intergovernmental Panel on Climate Change (IPPC) long-term projections on sea level rises can now be seen in an interactive way.

The project partners included the University of Cambridge’s Coastal Research Unit, global engineering firm Arup and the National Oceanography Centre with support from the Environment Agency.

It was funded through the £10.5m EuroSea initiative, part of the European Union’s Horizon scientific research and innovation programme. 

Mike Dobson, an associate with Arup, said: “I have been working in flood risk management for over 20 years trying to help make good decisions. It’s often pretty static – lots of modelling, lots of economics presented in a static report with conclusions at the end.

“We wanted to see what else was possible and bring it to life. The university managed to unlock the complex modelling which allowed us to do just that.”

Hull was chosen as the pilot because of its low-lying nature and concerns over long-term sustainability following major flooding events in 2007 and 2013, with the Environment Agency warning that water levels in the Humber could rise by over one metre in the next century because of the changing climate.

RISK: The tidal barrier over the River Hull. Picture by Tom Arran Commercial Photography

“These ‘once in a lifetime’ flooding events will become more frequent as sea levels rise and we experience more storms,” said Mr Dobson, who has spent the last 15 years working for Arup in the Humber area.

“Hull is low-lying. It’s similar in many ways to New Orleans due to its low-lying nature on the coast. There are 100,000 properties here potentially at risk from the most extreme weather events.”

Professor Tom Spencer, director of the Coastal Research Unit at Cambridge, added: “We are going to see more extremes and those extremes from a coastal point of view are going to be sitting on top of a rising baseline which is going to increase as we move into the next century – not just in Hull but everywhere.”

Until now, he said traditional flood risk assessments had only considered a limited band of uncertainties around rising sea levels.

“It was the first time we had ever done anything that has actually captured the uncertainties in a way that allows you to talk to policymakers.” he added.

The results are being used by the Environment Agency as part of its long-term flood management strategy for the Humber estuary, while the work in Hull has recently been shown at a United Nations workshop on flood risk.

Mike Dobson says the work Hull can be replicated anywhere in the world using the same tool.

“We have worked with Cambridge to design the whole process to be replicable. We want it to be globally applicable. The aim of the tool is to allow people to interact with problems at their specific location.

“For the first time, decision-makers can actually see the impacts of some of those more extreme projections and can start to make some more informed decisions.

“The power of what we have done is that we have brought all of the science through from the front end to the decision-makers with the visualisation.

“In the future, the tool can potentially be applied to towns, cities and regions around the world so that they can make better decisions about climate change – and, just as importantly, help explain these decisions to the public.”

Steven Downie, a fluid dynamics specialist at Arup’s technology and research team, also worked on the project.

He said: “This work is about the huge decisions that society has to make about adapting for climate change. We just don’t know how things are going to play out and we are only going to get a few chances to get these things right. It’s simply better to make good decisions and this tool will help this.”