Concrete Jungle to Sponge City
Imagine a city that isn’t ravaged by heavy rains, but designed to drink them up instead. Sponge cities shrug off impermeable surfaces in favor of a system that absorbs, filters, and breathes. They embrace nature instead of repelling it, allowing water to become an ally.
In a world where extreme weather patterns, from drought to severe rains, are increasing the risk and frequency of floods the world over, new solutions become a requirement.
Over the last 50 years, close to half (44%) of all disasters in the world were related to floods. Concrete is the second most-used substance in the world, trailing only water. By one account, the carbon mass of our trees, bushes, and shrubs is dwarfed by concrete. In an increasingly urbanized world, the combination of concrete jungles and rising rainfall can contribute to flash flooding.
Impermeable interventions like concrete, drainage pipes, pumps, and flood walls are ill-equipped to handle the effects of our rapidly changing climate. These conventional methods give rain no place to go. As the water accumulates, it builds up in drains, sewers, and rivers, eventually leading to flooding.
Turn to nature and we see an alternative approach: what Chinese landscape architect Kongjian Yu calls “sponge cities.” They create spaces for the water to be absorbed in the terrain through a variety of methods such as implementing permeable pavement, installing blue-green roofs, building wetlands and artificial ponds, and planting pocket gardens. These porous surfaces can then release the water slowly into aquifers, allowing it to be reused later.
SUGi Pocket Forests have a critical role to play in sponge cities. Take the Pirque Forest in Chile, for example, which transformed a spontaneous parking lot into a lot of parks, or the Serenity Forest in London, which took a corner from concrete slab to thriving forest. By breaking up concrete and replacing it with porous earth and densely packed plants, we create an environment in which the forest can soak up — or at least slow the flow of — rain and prevent flooding. These forests are working double duty, as they have the added benefit of reducing temperatures and air pollution, while enhancing biodiversity.
The Manhattan Healing Forest is a great example of a “spongy” pocket forest. Planted alongside the East River on Roosevelt Island, the forest is strategically positioned to capture water and stave off flooding. It serves as a physical barrier between ocean and land and helps to both prevent pollutant runoff and enhance air quality.
Roosevelt Island, New York City, NY, USA
Manhattan Healing Forest
Planting for Resilience.
Nestled along the southern banks of Roosevelt Island, the Manhattan Healing Forest stands as a beacon of hope, offering a haven of tranquility for the almost 12,000 residents amidst the bustling cityscape.
The strong currents of the New York Estuary, aka East River, lap at our shorelines, an ever present reminder of the island’s beauty and vulnerability. As storm surges threaten Roosevelt Island, and flood models paint a concerning picture, Manhattan Healing Forest emerges as a symbol of hope and adaptation. This SUGi Pocket Forest is strategically positioned to stabilize the land and capture water, serving as a living barrier against flooding and erosion, preventing pollutant runoff and enhancing air quality.
But Clifton Urban Forest in Karachi, Pakistan demonstrates the real power of a sponge city. Like numerous cities across the region in recent decades, Karachi has become increasingly vulnerable to both extreme heat and flooding. As these conditions worsen, the need for green space is ever more pressing.
Clifton Urban Forest was designed to restore the city’s poor environment, purify the air, combat the effects of the Urban Heat Island Effect, and absorb thousands of gallons of runoff water after heavy rainfall. This last element is particularly key when considering the dual pressures of extreme heat and flooding that Pakistan faces. High temperatures cause soil to harden. When rain falls, it either runs off and causes flooding, or evaporates, which leaves communities vulnerable to drought. A forest like this can hold the water, staving off each of these hazards. In short, it is an environmental powerhouse.
Karachi, Pakistan
Clifton Urban Forest
A game-changing green lung in the center of Karachi.
Our aim was to create evergreen, sustainable forests to restore Karachi’s degraded environment. ‘Clifton Urban Forest’ was re-designed to answer several challenges facing a modern-metro lifestyle.
The forest serves as the “Air Purifier and Lungs” of the area, also helping to bring the ambient temperature down. Moreover, they also hold thousands of gallons of runoff water after rain.
The best part about “doing tai chi with water,” as Yu puts it? Sponge cities can be implemented at any scale, from the municipal to individual household level. Each of us can do our part to conserve water and diminish the harmful effects of climate change.
References:
https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-4/
https://www.bbc.co.uk/news/science-environment-46455844
https://www.theguardian.com/cities/2019/feb/25/concrete-the-most-destructive-material-on-earth
https://www.theguardian.com/environment/2016/jul/25/why-concrete-rain-flash-floods-weatherwatch
https://www.turenscape.com/en/about/info.html
https://www.nytimes.com/2024/03/28/climate/sponge-cities-kongjian-yu.html
