Storm Bert: After floods hit Britain, how can engineers respond?
Flood defences are going to have to get a lot better in the future.
As I write this, people around the UK, especially in England and Wales, are heaving buckets of floodwater over walls, salvaging what they can from badly damaged homes or businesses – and wondering what will prevent a similar deluge the next time a storm arrives.
Storm Bert has killed at least five people, inundated multiple towns and villages, and caused transport chaos. Climate scientists, and the Met Office, have long warned that storms like this could become stronger and more frequent due to climate change.
“I’m perfectly honest with people when I discuss this, there are some communities – some coastal and river environments – that it is going to be very, very difficult to protect entirely from now on,” Wales’ Deputy First Minister Huw Irranca-Davies told BBC Radio 4’s World at One programme this lunchtime.
He also suggested that better flood warning systems and defences would be needed in the coming years: “We need to be imaginative about thinking about the way forward.”
It’s dam time
Many commentators would highlight the importance of slashing emissions, in order to tackle climate change and avoid its worst effects. But some of those effects are unfolding already and still more, especially in terms of extreme weather, are unavoidable. Architects, engineers and planners are all going to have to prepare for worsening floods in the coming years.
Over the years, some British people have even taken matters into their own hands. Such as the man in Worcestershire who built a huge wall around his house to keep floodwater out.
In 2015, a report from a UK public inquiry into flood mitigation found that the country faced significant threats from increased rainfall and rising sea-levels. At the time, the report recommended that the then-government “undertake an investment programme to retrofit towns and cities to make them more resilient, as an additional aspect of their flood defence spending”.
Certainly, British governments have invested in improving flood defences during the intervening years. This has included spending on things like flood walls, tidal barriers, embankments and drainage systems to help manage surface water or extreme runoff. One of the flagship projects has been the Boston Barrier Scheme, on the River Witham in Lincolnshire. Its 25 metre-wide gate became operational in 2020.
But there are so many climate risks to consider. Engineers, including those at consultancy Arup, are now increasingly using multiple climate models when designing new flood defences, according to a story published in August over at New Civil Engineer.
There is arguably much more to be done, if the trail of destruction left by Storm Bert is anything to go by.
Sponge cities
Efforts to establish “sponge cities”, or districts, which are designed to soak up excess rainwater, could help. Earlier this year, I covered the concept of “de-paving” for BBC Future. If you replace paving slabs and tarmac with permeable coverings or planting, this can help water seep into the ground rather than collect and exacerbate flooding.
Nature-based solutions could also help, including those that direct floodwater to pre-existing flood plains. Protecting the form and shape of rivers could mean that they are more likely to absorb heavy rainfall, and natural features of coastlines such as dunes and wetlands ought to reduce the impact of storm surges. It’s worth noting that, this year, sustainable drainage systems (called “SuDS”) including, for example, soakaways will become mandatory for new building developments in England, if the development in question exceeds 100 square metres in size.
A key feature of both the floods caused by Storm Bert, and the recent devastating floods in Spain, is that they unfolded so quickly. The thing about future flood defences and solutions is that they are going to have to stand up to extremely heavy rainfall and flows of water. There’s always another storm coming.
If you have ideas for sustainable flood defences that could help communities protect themselves from future flooding, please tell me about them by dropping an email to thereengineernews@gmail.com.