It’s time to stop pitting green and grey interventions against each other:
When it comes to managing floods, there is no ‘either/or’ choice between engineering and working with nature. And yet the arguments surrounding this pit one versus the other and have only one outcome – one to the detriment of flooded communities. Arguing about tactics is the wrong approach. What is needed are strategies with clear goals, which utilise all the tools available to deliver them, avoid environmental damage, and secure other benefits in the process.
The evidence is clear. “It is widely accepted,” explains the Climate Change Committee’s authoritative Well Adapted UK report, “that flood risk is best managed through a portfolio of measures.” This point is accepted in flood strategies and policy statements across the UK’s four nations. Yet, in our public conversations, far too much time is spent contrasting flood risk tools with each other.
To manage floods, you need to act at three levels: the source of the water, the pathway it travels on, and the ‘receptor’ – the places it ends up in. There is no one single trick that gets you where you need to go. Instead, you need clear goals, a strategy, and lots of different things working in concert. The best management looks across all these locations, at the whole catchment, and deploys a variety of management tools.
And yet it is still very common to hear people counterpose ‘natural’ or ‘green’ techniques with ‘grey ones’.
‘Green’ interventions conjure up images of ‘leaky dams’, beaver populations, and river re-meandering. By acting on landscapes, flood risk managers aim to enhance these landscapes’ capacity to hold back water, slowing flow of rivers in order to diminish their peak.
Built or ‘grey’ interventions, by contrast, conjure up ideas of concrete walls or schemes like the Thames Barrier. Yet these measures increasingly work with natural processes and in combination with nature-based solutions across catchments, including things like bunds to enhance a floodplains’ capacity to store water temporarily.
The evidence is clear that both are needed to work effectively. The Climate Change Committee, again, states that “(b)uilt flood defenses continue to provide the largest contribution to risk reduction in locations with substantial existing exposure … and Natural Flood Management provides an important and robust contribution to reducing fluvial risk as part of the portfolio.”
A narrative that contrasts these measures undermines our capacity to deal with flooding. It risks pitting downstream communities on the frontline of climate change against nature protection advocates, creating tensions in communities and complicating desperately needed policy implementation.
It is bad politics. If flooded communities see the solutions they need turned down in the name of nature protection, they will inevitably conclude that nature protection advocates do not care about them and will sour on the need to preserve biodiversity. Nature protection advocates, on the other hand, will end up championing nature-based flood risk reduction while facing active opposition from the people these measures are meant to benefit. Divisions between flooded people and nature advocates risk undermining both their causes.
If the goal of flood risk management is to reduce flood risk as sustainably as possible, it is vital for communities and policy makers to understand that one type of intervention cannot replace the other. What is desperately needed is an evidence-based approach that focuses on risk reduction outcomes instead of individual tactics, and for different stakeholders to work together to deliver such outcomes.
It is time the public conversation catches up.