Author: Kim Harrisberg

Are 'sponge cities' enough to curb climate-fueled floods?

Source(s): Japan Times Ltd., the
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With its coastal forests, sugarcane farms and sweeping beaches, South Africa’s Durban might appear to be an ideal “spongy” city — one capable of absorbing water, which can be useful in combatting both flood disasters and drought.


One year after the city’s devastating floods, green experts are highlighting the importance of using what cities already have — such as parks and rivers — to reduce risks, and figuring out what else they need to be as resilient as possible as climate change threats intensify.


But sponginess is just a starting point, they say, noting that policies, funding and infrastructure to protect communities are equally important in building resilience against future weather-related disasters.


The company calculates how much urban surface area is covered by “blue and green infrastructure” — including grass, trees, ponds and lakes — and how much is covered in “grey infrastructure,” such as concrete, pavement and buildings.

Its digital mapping tool allows cities to gauge the best use of available space — from rainwater harvesting to ponds and inner-city gardens — to boost sponginess, and to determine the risks of not doing so.

Arup’s most recent sponginess report — from 2022 — examined five African cities — Cairo, Durban, Kigali, Lagos and Nairobi — with Durban earning the second highest sponginess rating at 40%.


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Hazards Flood
Country and region South Sudan
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