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Many of the world’s poorest people live in regions most susceptible to flooding. In Northeast IndiaSome residents have had to rebuild their homes at least eight more times over the past decade. In Africa, the continent’s largest city, Lagos in Nigeria, may become unliveableDue to severe flooding, while a recent tropical storm Ana flood affected Many thousands of peopleTo the south of the continent
The situation is expected to worsen in the next few decades, especially for many of the world’s largest cities in lower and middle income countries of Africa, Asia and Latin America. Their population is expected increase significantly in the next century. According to one estimate, Lagos could have a population in excess of 88 million people by 2100. academic estimate.
These cities are already improving their infrastructure. However, the majority of the focus is still on large-scale engineering solutions (e.g flood walls and embankments), rather than holistic plans that involve all levels of society. As we recently argued in our Research, these cities must instead become truly “resilient societies” – before it is too late.
Blue-green infrastructure
There have been attempts to go beyond engineering. One way to do this is to use the planning system as a tool to integrate rivers, canals, wetlands, or forests (the blue), with trees, lawns, or forests (the red). This can involve anything from small-scale “rain gardens” that allow water to drain naturally through soil, through to much larger-scale artificial wetlands or ponds.
“Sponge cities”, an approach first introduced in China in 2013, are a nice example of this in practice. The idea behind a sponge city is to use nature to absorb, clean, and use rainwater rather than using concrete to channel it away. The cities are designed to absorb stormwater without becoming too saturated, much like a sponge.
For example, the port city NingboThe location of one of our offices transformed a 3km strip made of brownfield into an ecological corridor and public park.
Lei Li, Author provided
Shanghai has also turned its new “Land of Starry Sky” park (so named because it neighbours an astronomy museum) into a sponge facility, using permeable materials to absorb rainwater. The Chinese government recognized that sponge cities could achieve sustainability goals better than traditional engineering structures.
Contrarily, there is a much more alarming scenario in LagosOther coastal cities that heavily rely upon insufficient engineering systems to protect against flooding.
Mikayleigh Haarhoff / shutterstock
We need cities that are resilient
In our new ResearchWe studied the existing practices and identified a major problem in the lack of engagement with key stakeholder (such as small businesses and local industry) These stakeholders are key to improving the outcomes of blue-green infrastructure. It is also crucial that engagement is easy thanks to widespread use of digital and mobile technologies. Climate resilient infrastructures should be considered co-production of all these groups.
One example is sponge cities, which successfully combine nature-based engineering with traditional engineering. These cities struggle to get everyone involved in proactive thinking about flood risk. We believe that flood management is possible only if everyone is involved in preventing flooding, adapting to their worst effects, and ensuring a quick return to pre-disaster status.
This social engagement is crucial to reducing flood impacts, especially in the poorer and more vulnerable areas of the world. Our research shows that a flood management plan must be developed that incorporates social, natural and engineered systems.
