Blog: Coastal flooding: Let's start planning for the long-term

We all know that sea level rise is happening and also that the rate of rise is set to accelerate.  There are many factors influencing this rise, one of the most significant being thermal expansion – as the sea gets warmer it expands. I think this direct correlation between a warmer world and higher sea levels is a good way of communicating the risks we face now and will face in the future.

We need to do much more to communicate how sea level rise creates very real threats to our country, and we also have to start properly planning for long-term adaptation. Working with the people most directly affected, in ways they can readily engage with, is essential to developing successful and acceptable adaptation strategies.

How will rising sea levels affect flood defences? 

If you consider a typical sea-defence wall protecting a coastal area in the South of England, it could be about waist high today. By end of this century, the same wall would have to be head high to cope with the increased risk from rising sea levels, and that’s ignoring waves. By the end of the following century there is a very real chance that the wall would need to double in height again. 

The economic, visual and social impact of massive walls and defences is something I don’t think engineers, planners or communities are really facing up to. The risks from such high defences are immense. What if someone forgets to shut a gate? What if there’s a catastrophic overtopping or a breach? Whole communities could be cut off.  

It’s clear to me that in as little as a couple of generations we are going to be facing a major change in how we relate to flood risk on our coasts. This will probably require radical changes to where we live and work. I worry that the limited time horizon of planning policy means that instead of coming up with a long-term strategy, we are just kicking the can down the road. 

Government is not blind to the problem and the Environment Agency’s draft National Flood and Coastal Erosion Risk Management Strategy for England, for which consultation has recently closed, is a big shift in approach. 

 

“We can tackle flooding and coastal change if we act now. Our vision is for a nation ready for, and resilient to, flooding and coastal change – today, tomorrow and to the year 2100.”   

~ Draft National Flood and Coastal Erosion Risk Management Strategy for England

 

I feel, however, that we need to be looking well beyond 2100 – sea-level rise will continue long after that date – so we can start agreeing on approaches that will make our communities resilient in the long term.    

What can we do now to safeguard the future?

One measure is to ensure that today’s projects go further than today’s requirements. For the Barking Riverside project in London, rather than flood defence walls WSP has proposed a very wide and high defence that is part of the development system; providing a much safer and more robust response to current and future flood risk from the tidal Thames than a typical wall. 

The platform that is being created includes natural landscaped areas, wildlife sites and places for business and transport. It will protect – well above current design standards – both the 11,000 new homes that make Barking Riverside one of the largest brownfield developments in Europe and the low-lying area of existing city behind it. It will provide long-term value by offering better protection for longer. It is also a defence that nobody will notice is there, as it is integral to the development.

Better protection might not always be the answer. What if, as a nation, we were to accept that some areas will flood and instead plan to get people out (and back in) quickly and safely? New approaches such as Floodly, a tool developed by WSP that uses machine learning to offer more accurate flood warnings, could help with this. So could reforms to planning guidelines – giving preference to flood-resilient commercial development in flood-prone areas.

Whatever route is taken, coastal flooding shouldn’t be considered in isolation. Instead of being driven mainly by one agency and focusing purely on flooding, projects should involve a range of actors and consider social, demographic and other factors too. For example, could a scheme to reduce flood risk also improve wellbeing (by providing walking and cycling routes), capture carbon, generate income, carry services, increase biodiversity and more? 

How can we change the delivery model?

This approach would mean changing how large infrastructure is delivered – rethinking everything from how communities are consulted to how developers make their money. Consultants must be challenged to use their expertise to broker projects that don’t just solve flooding problems but also enhance wellbeing, education and other factors – and which can therefore draw on additional funding for these areas.

This wider pool of funding is likely to go further; unlocking multiple benefits at once can be cost-effective – as developing countries have found. On the Ivory Coast I’ve seen first-hand how a community leader successfully implemented a project to reduce flood risk in the slums, tackling fire risk, flood risk, power and sanitation at the same time. 

Surely countries like the UK can embrace this sort of approach. I believe they can, but it will require a shift in how our skilled professionals behave; able to work across planning, design and community engagement. 

It will also require a shift in focus by communities: away from our nation’s traditional preoccupation with short-term property values, embracing instead the benefits of building resilient, healthy, prosperous and sustainable communities for the long term.


WSP Author:

  Hamish Hall: Director, WSP

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