Extreme rainfall and flash flooding are becoming increasingly frequent and severe, but most cities are ill-equipped to cope with these risks. In highly concretised urban environments, the “sponge city” is an urban planning strategy that builds climate resilience through restoring water’s natural patterns. We’ve been talking about sponge cities since 2016, and we’re thrilled to finally speak to the “Father of Sponge Cities,” Dr. Kongjian Yu.

He is the Founder and Principal Designer at Turenscape, an award-winning design institute based in Beijing that specialises in holistic landscape design solutions for the challenges of urban expansion, environmental degradation, and climate change. We ask Dr. Yu about his approach of mixing “old” and “modern” technologies and philosophies to futureproof cities against climate change.

CWR: Dr. Yu, we are big admirers of your work on “sponge cities.” Can you tell us how you first developed or encountered this idea? How widely has this model been adopted around the world?

Dr. Kongjian Yu (KJY): The sponge city idea was born from my 17 years growing up in a small village in Zhejiang, shaped by the rhythms of the monsoon. Every summer brought floods that destroyed homes and took lives, yet that same water sustained our rice fields, filled our ponds, and defined our way of life. I remember digging ponds with commune members during droughts, and even fighting over pond access—because in that landscape, water was life.

I learned to swim in White Sand Creek, a stream full of frogs and reeds, alive with seasonal change. Later, it was channelized in concrete—straightened, silenced, and stripped of life. The same fate befell countless ancient ponds and irrigation systems, filled and buried under concrete in the name of progress. The entire rural landscape was industrialized—flattened, piped, and paved—leaving new towns, cities, and farmlands vulnerable to inundation without resilience.

After the 1998 Yangtze floods, it was clear that water had become an enemy…

…sponge cities can restore our respect for water & is now a national policy in China

After witnessing the catastrophic Yangtze floods in 1998, I saw clearly: we had turned water into an enemy, and our gray infrastructure was collapsing under its own rigidity. The sponge city became my answer—a way to restore our respect for water, to work with it rather than against it. Today, it has been adopted as national policy in China, with thousands of projects implemented in over 200 cities. The concept is also inspiring action across Southeast Asia, South America, and the European Union.

It is more than a technical solution—it marks a cultural shift, a revival of the ecological wisdom we once lived by and must now urgently reclaim.

CWR: Slowing down water flows can greatly reduce the intensity of flash floods, but what are the other benefits of “slow water”?

Dr. KJY: “Slow water” is a poetic yet powerful concept. It is the antithesis of modern engineering’s obsession with speed and control. When we slow water down, we create time and space—for life to flourish, for the ground to absorb, and for beauty to emerge.

“Slow water” has many ecological, social, & economic benefits…

…through the art of slowing down, it invites a more symbiotic relationship with our environment

Ecologically, slow water enhances infiltration, replenishes groundwater, and filters pollutants. Socially, it brings water back into the city as a life-giving element. Parks become wetlands, streets become greenways, and floodplains become community spaces. Children play, birds return, and the urban citizen rediscovers a forgotten intimacy with nature. Slow water also buffers climate extremes—cooling the air, mitigating drought, and supporting biodiversity. Economically, it reduces the costs of grey infrastructure and creates long-term adaptive value.

Philosophically, it reminds us to be humble. In ancient Chinese culture, water is wise precisely because it is soft and slow—it yields, but it shapes mountains. The sponge city, through the art of slowing down, invites a more symbiotic relationship with our environment. In embracing slow water, we reclaim the lost poetry of our cities.

CWR: In addition to urban floods, low-lying cities are extremely vulnerable to fast rising seas. Engineered coastal defences are often presented as the only solution but recently, Turenscape built a breathing sea wall in Hainan. How did the new permeable, vegetated design improve on the original concrete sea wall?

Dr. KJY: Traditional concrete sea walls treat the sea as an enemy—cutting off land from water, amplifying erosion, and sacrificing both ecology and public life. In contrast, the “Breathing Sea Wall” reimagines the coastline as a living, porous boundary that adapts to tidal rhythms while providing protection, ecological regeneration, and civic space.

Traditional concrete sea walls treat the sea as an enemy…

…the “Breathing Sea Wall” reimagines the coastline as a living boundary that provides protection

In Sanya, we restored a degraded riverfront behind a concrete flood wall into a dynamic mangrove landscape. The wall was breached and replaced with a system of interlocked landforms that invite the tide inland in a controlled manner. These “breathing fingers” not only protect young mangroves from monsoon surges but also allow water to flow, settle, and recede naturally. The result is a resilient edge where vegetation thrives, biodiversity flourishes, and flood risks are reduced through ecological means.

In Haikou’s Jiangdong Beach Park, a 4-meter-high sea wall was deconstructed and reshaped into terraced, vegetated planters. This breathable form absorbs storm surges and channels overflow into inland sponge landscapes. The design preserves the foundation of the original wall underground for stability, while transforming its surface into a living edge. Native plants now hold the shoreline, filter runoff, and soften the impact of waves.

Both cases show that a Breathing Sea Wall is not only more adaptive to rising seas—it restores ecological function and reconnects people with the water. It is a new paradigm: protective, porous, and alive.

CWR: Your designs revisit traditional landscaping methods like terracing, ponds and dykes to solve urban environmental challenges. Humans have been adapting to our environmental conditions for thousands of years, so why do you think the “wisdom of the peasantry” has been lost in modern cities?

Dr. KJY: The “wisdom of the peasantry” is a legacy of survival—growing food, managing floods, and living in rhythm with nature. Rooted in millennia of adaptation, it shaped landscapes like Yunnan’s rice terraces, the Pearl River Delta’s fish ponds, and Yellow River cities’ regulating ponds. These are early, effective nature-based solutions—low-tech, ecologically sound, and deeply place-based.

The “wisdom of the peasantry” can be used for early effective nature-based solutions…

…e.g. Yunnan’s rice terraces, the Pearl River Delta’s fish ponds & Yellow River cities’ regulating ponds…

Industrialization rejected this vernacular knowledge, replacing it with concrete and mechanical control systems. In doing so, we severed ties to both ecology and cultural identity.

Today, with climate change accelerating, this lost wisdom becomes urgently relevant. Design must shift from domination to restoration—learning from the past to shape resilient futures. Integrating traditional agrarian strategies with modern science allows us to build landscapes that are productive, adaptive, and meaningful.

The sponge city embodies this approach. Like the ancient farms it echoes, it absorbs, stores, and reuses water—not through force, but in harmony with nature. This is not nostalgia, but innovation grounded in time-tested knowledge. Peasant wisdom offers a cyclical, locally attuned vision—essential for cities facing ecological uncertainty.

CWR: Some people might view sponge designs as too small in scale to address the magnitude of the climate crisis, especially against escalating climate risks. How can sponge cities be scaled up to become a sponge planet?

Dr. KJY: It’s true that some still misinterpret the concept of the sponge city as a loose collection of Low Impact Development (LID) strategies—perhaps a bioswale here, a rain garden or wetland there. This narrow view, shaped by technocratic misreadings and fragmented policy documents, has led to a diluted and superficial version of the original vision. But such an interpretation is a fundamental misunderstanding.

The sponge city is not about scattered green patches or decorative permeability. It is a systems-based, nature-driven strategy aimed at reprogramming the urban metabolism. It marks a paradigm shift—from rigid, hard-engineered infrastructures to resilient, adaptive landscapes that work with water rather than against it.

To truly scale up, we must think beyond the boundaries of individual cities…

…we must plan in terms of watersheds & bioregions

To truly scale up, we must think beyond the boundaries of individual cities. We must plan in terms of watersheds and bioregions—not merely administrative districts or urban cores. That means restoring floodplains, safeguarding upland forests, reconnecting rivers to their deltas, and allowing nature’s hydrological systems to function once more as the foundation of urban resilience.

At Turenscape, we have demonstrated how this thinking can transform entire urban and regional systems—from the 20-kilometer-long drainage corridor in Haikou, designed not only for flood mitigation but for creating public space and biodiversity; to managing monsoon flooding in high-density urban centers; to regional ecological security planning based on what I call “negative planning”—using ecological infrastructure to guide urban growth, rather than letting urbanization dictate land use. These are not isolated interventions, but regional-scale ecological infrastructures that integrate human and natural systems.

To evolve to a sponge planet, we must institutionalise the principles of permeability, water retention, slowing runoff & adaptive design

To evolve from sponge cities to a sponge planet, we must institutionalize the core principles of permeability, water retention, slowing runoff, and adaptive design into global norms. This requires more than just new design tools—it demands new policies, investment frameworks, and a shift in cultural narratives: we must begin to see water not as waste to be drained, but as life to be embraced.

The climate crisis is global in scale—but so is the wisdom embedded in the sponge. Nature has already shown us how to absorb, adapt, and endure. We must learn from it. A sponge planet is not a utopian ideal; it is a pragmatic, nature-based, and deeply hopeful response to the uncertain future we now face.

CWR: Lastly, as climate disasters become more common, tragic as the reality is, there are also opportunities to rebuild back better. What advice can you share to help practitioners think more holistically about climate adaptation, ecological restoration, and livability?

Dr. KJY: A crisis should never be wasted. Each flood or drought is a wake-up call—an opportunity to reimagine our cities, not just to withstand climate shocks but to flourish in spite of them.

My advice is simple: think like water. Water adapts. It flows, finds balance, and supports life. This mindset should guide how we design—starting with the land. Understand its patterns, honor its memory, and restore its natural capacity to absorb, filter, and regenerate.

Dr. Yu’s advice is simple – think like water, think in layers & design with nature…

…we should stop building monuments to fear & start create landscapes of resilience

Think in layers—ecological, cultural, social—and break down silos. Engineers, ecologists, artists, and policymakers must collaborate. Infrastructure should be more than utility—it should be habitat, public space, and art. Prioritize the vulnerable and empower communities to shape their futures.

Above all, design with nature. Beauty isn’t a luxury—it fuels emotional connection and long-term stewardship. When people love their landscapes, they protect them.

Every disaster holds the seed of transformation. Let’s stop building monuments to fear and start creating landscapes of resilience—places that heal, adapt, and bring life back to our cities.

Further readings

• Sponge City Is Transforming Urban Flood Management – Dr. Chan, Dr. Thadani & Li explain how Sponge city program (SCP) combat urban flood risks in China & the social media’s role
• Hong Kong: A Climate Resilient Sponge City – Leung from the Drainage Services Department shows how HK is building flood resilience under climate change
• Nature as Leverage: Design Approach For Climate Change – Despite the massive climate challenges, Probst, Associate Director at MLA+, remains optimistic thanks to new design thinking methodology – ‘Nature as Leverage’