In 2019, a bold plan emerged from the Thai government to rejuvenate an abandoned tobacco factory in Bangkok, transforming it into a vibrant public park. This initiative provided landscape architect Chatchanin Sung with a unique opportunity to tackle another critical issue for the city: flooding.
As Bangkok, a sprawling metropolis of 11 million residents, grapples with the stark realities of climate change, effective water management has become paramount for survival. Experts caution that escalating rainfall and rising sea levels may soon submerge parts of the city.
Similar to the challenges faced by Los Angeles amid intensifying droughts and floods, Chatchanin observed that Bangkok’s stormwater infrastructure was at a breaking point. Rapid urbanization had encased the city in impermeable surfaces, obstructing natural water drainage.
This change left the city’s extensive network of over 1,600 urban canals inundated and struggling to manage stormwater, as they had transitioned from transportation channels to emergency flood defenses.
“The canal water mixes with public sewage, leading to poor water quality,” Chatchanin noted. “The park project presented an opportunity to absorb and purify this water.”
The new Benjakitti Park, expanding over 102 acres, was designed in collaboration with Kongjian Yu, a leading advocate for the “sponge city” model of urban water management. This approach signifies a shift from traditional ‘gray’ infrastructure, which hastily flushes water away, to designs that embrace water’s potential.
Under the sponge city concept, cities like Bangkok can mitigate flood risk by enhancing absorbency in urban surfaces, thereby capturing stormwater before it escalates into pollution-laden runoff.
Their innovative design, which opened to the public three years ago, showcases how urban water management systems can enrich community aesthetics and recreational opportunities. The previously degraded brownfield is now a thriving destination for bird watchers and includes refurbished badminton and pickleball courts.
A vital component of the park’s design includes a complex wetland system lined with diverse aquatic plants, which naturally filter pollutants from stormwater as it flows through the park. At the park’s edge, this water ultimately feeds into a serene pond surrounded by small islets, enhancing both ecological and recreational value.
During the city’s rainiest months, the park can capture an impressive 23 million gallons of stormwater, replenishing underground reservoirs in the process. Chatchanin remarked, “Last year, during heavy rains, the park did flood, but it absorbed the water much more efficiently than before.”
The pond within the park is a testament to this success, with clear water that is devoid of the foul odors and oily residues that once characterized the canals nearby. The presence of dragonflies is a positive indicator, signaling improvements in water cleanliness.
While acknowledging that this park alone cannot resolve Bangkok’s broader water management issues, Chatchanin expressed hope that its success could inspire other cities to reevaluate their relationship with water. “People desire quick fixes,” she observed. “However, concealing the problems is not a solution. You can’t simply elevate structures on stilts or flush out water; those issues will return.”
Kongjian Yu, who has dedicated his career to promoting sponge cities, believes that cities should adapt to flood conditions, rather than attempting to outrun them. Yu’s work, which has earned him the prestigious Oberlander International Landscape Architecture Prize, draws inspiration from a near-death experience he encountered as a child in rural China.
At ten years old, Yu was swept away by a swollen river during monsoon season but managed to save himself by grabbing onto the river’s reeds and willows, which slowed the current. This formative experience instilled in him a profound understanding of coexisting with nature’s forces.
Having earned a landscape ecology degree from Harvard University’s Graduate School of Design, Yu worked for SWA Group in Los Angeles before returning to China in 1997. Disturbed by the prevailing inclination to encase urban environments in concrete, he began advocating for more sustainable practices, writing to municipal leaders about the dangers inherent in traditional infrastructure.
The sponge city initiative follows three foundational principles: retain, slow down, and embrace water. This philosophy calls for a reduction in unnecessary pavement and concrete, allowing for natural absorption and drainage.
Initially, Yu faced resistance and skepticism; some perceived him as an outsider threatening China’s infrastructure. However, a watershed moment occurred in 2012 when a catastrophic flood in Beijing, which claimed numerous lives, shifted public and governmental perspective toward his sponge city model.
Following this disaster, then-leader Xi Jinping championed the sponge city concept, embedding it into the national policy agenda in 2015. The Chinese government has since allocated over $28 billion to fund upward of 33,000 sponge city projects across 90 cities, aiming to capture and repurpose at least 70% of rainwater by 2030.
By 2020, sponge city projects had demonstrated their effectiveness, with over 40,000 initiatives completed nationwide, contributing to the recycling of approximately 3.8 trillion gallons of rainwater that year—equating to roughly one-fifth of China’s annual urban water supply.
Projects include not only wetlands designed to mitigate urban flooding but also coastal solutions like a mangrove forest in Sanya, Hainan, which protects against saltwater intrusion and rising sea levels.
Yu emphasized the philosophy of not building too near water’s edge and creating natural buffer zones instead of traditional flood barriers. This approach has simplified sponge city designs and made them cost-effective, suitable for a range of urban contexts.
Benjakitti Park serves as an illustrative example, constructed for just $20 million by a military group mostly unacquainted with environmental landscaping. Yu crafted the original design on a napkin during a flight to Bangkok, ensuring that the vision was straightforward enough to be practically achieved.
Despite such successes, the journey toward establishing sponge cities has not been without challenges. Wetlands can inadvertently become breeding grounds for mosquitoes, which can deter community support. Moreover, local governments typically shoulder up to 80% of project costs, making essential private investment increasingly crucial.
Critics have pointed out that several high-profile sponge city projects, like those in Zhengzhou, Henan province, have not been immune to flooding disasters, raising questions about their design efficacy. Yu asserts that a city’s inability to cope with flooding signals inadequacies in its sponge infrastructure.
The philosophy lies not in eradicating concrete but in harmonizing gray infrastructure with green solutions—an upgrade to the status quo.
Globally, other cities have been exploring similar concepts to address flooding while enhancing urban purpose. In Singapore, for instance, the Active, Beautiful, Clean Waters (ABC Waters) Programme has been repurposing waterways and reservoirs into public parks capable of absorbing stormwater since 2006.
The Netherlands, grappling with its own history of combatting water encroachment through architectural ingenuity, has initiated strategic efforts to let certain rivers flood in designed areas to safeguard others.
In Los Angeles, awareness is growing regarding the shortcomings of existing impermeable flood-control systems. Significant stormwater is currently wasted, with potential to capture 490,000 acre-feet annually within the area encompassing Long Beach and Anaheim.
The Safe Clean Water Program, approved through ballot Measure W in 2018, is among the city’s initiatives aimed at making L.A. spongier and less dependent on imported water.
This program imposes a property tax on impermeable surfaces, supporting municipal stormwater capture projects with yearly grants totaling around $300 million. The goal is to capture a staggering 98 billion gallons of stormwater each year.
Despite the urgency and necessity of these projects, experts warn that achieving these ambitions may take decades. Progress has been slow, with only 30 acres of green space added in the initial three years following program implementation.
As reported by Los Angeles Waterkeeper, recent advancements have begun to accelerate, with nearly $1 billion allocated across 130 new projects. Still, myriad challenges remain, including a lack of federal support and the protracted bureaucratic procedures involved in obtaining necessary project clearances.
Bruce Reznik, executive director of Los Angeles Waterkeeper and a part of the Measure W scoring committee, expressed concerns about spiraling project costs, reflecting on the difficulty of keeping these initiatives financially feasible.
As urban areas like Bangkok and Los Angeles seek sustainable solutions to combat flooding and enhance community resilience, innovative concepts such as sponge cities may represent crucial strategies for adapting to climate challenges in the years to come.
image source from：latimes
