urban flooding solutions climate change
Cities across the globe face escalating threats from urban flooding, driven by climate change, rapid development, and outdated infrastructure. Bangkok and Los Angeles exemplify this crisis, with both cities grappling with increasingly frequent and severe rain events that overwhelm conventional flood control systems.
Bangkok, a sprawling metropolis of 11 million built on low-lying swampland, is especially vulnerable as rising sea levels and intense storms threaten to submerge large parts of the city within decades. Meanwhile, Los Angeles confronts intensified droughts alternating with floods, exposing the limitations of its concrete-lined L.A. River and other “gray” infrastructure designed primarily to channel water away quickly without retaining or reusing it (Kim, 2025).
These challenges call for a fundamental shift in urban water management, moving beyond engineered drainage toward solutions that integrate natural water absorption and retention. Traditional systems prioritize rapid removal of stormwater to prevent immediate flooding, but this approach often exacerbates downstream risks and pollution.
Impermeable surfaces such as concrete prevent rainwater from soaking into the ground, increasing runoff volumes that overload drainage networks and degrade water quality. Bangkok’s 1,600 urban canals, once vital for transport, now primarily serve as stormwater conduits but frequently flood and mix with sewage, creating health hazards. Recognizing this, urban planners and landscape architects are advocating for “sponge city” models that reimagine urban environments as porous, water-absorbing landscapes capable of mitigating floods while improving ecological and community benefits (Kim, 2025).
This paradigm shift emphasizes resilience by retaining, slowing, and embracing water rather than fighting it.
sponge city water management strategy
The sponge city concept originated in China and gained momentum following catastrophic floods in Beijing in 2012 that exposed the vulnerabilities of conventional urban drainage. Kongjian Yu, a leading landscape architect and sponge city pioneer, describes the approach as one that removes unnecessary concrete and pavement, employs wetlands, permeable soils, and green infrastructure to capture and clean stormwater.
Yu’s philosophy centers on three principles: retain, slow down, and embrace water. Instead of building impermeable barriers, sponge cities create natural buffers that absorb rainwater, reduce flood peaks, and recharge groundwater, while also enhancing public spaces (Kim, 2025). This low-cost, scalable strategy contrasts sharply with expensive, inflexible gray infrastructure.
China’s national adoption of the sponge city program since 2015 has resulted in over 33,000 projects across 90 cities, with government investment surpassing $28 billion. By 2020, these projects recycled approximately 3.8 trillion gallons of rainwater annually, about one-fifth of China’s urban water supply.
Examples include wetland parks, mangrove buffers against coastal erosion, and permeable urban landscapes that provide recreational and ecological functions alongside flood mitigation. The “Fish Tail” sponge park in Nanchang and the mangrove forests in Sanya illustrate how integrating nature-based solutions can protect cities from floods and saltwater intrusion while creating community assets (Kim, 2025). The program’s success demonstrates how embracing water rather than resisting it can build urban resilience effectively.
Benjakitti Park sponge city transformation
Bangkok’s Benjakitti Park expansion offers a compelling real-world example of sponge city principles in action. Once a polluted brownfield site and former tobacco factory, the 102-acre park was redesigned to absorb and clean stormwater, transforming it into a multifunctional urban green space.
Fed by a nearby canal, the park features a long system of wetlands populated with aquatic plants that filter pollutants from stormwater before releasing cleaner water into a large pond. The porous landscape and retention ponds capture an estimated 23 million gallons of stormwater during the city’s rainy season, reducing flood risk and replenishing underground reservoirs (Kim, 2025). Beyond flood management, the park provides social and environmental benefits, including forested walkways, bird-watching areas, and repurposed recreational facilities, demonstrating how sponge city designs can enhance urban livability.
Though the park itself flooded during heavy rains, it absorbed water more quickly than surrounding areas, underscoring the effectiveness of such interventions. This success challenges the notion that urban water problems can be resolved solely through gray infrastructure or avoidance strategies like raising buildings on stilts.
Instead, integrating natural water absorption into city planning can yield durable and multifaceted solutions that serve both people and ecosystems.
sponge city principles urban adaptation
Globally, sponge city principles have inspired diverse adaptations beyond China and Thailand. Singapore’s Active, Beautiful, Clean Waters (ABC Waters) Programme has transformed waterways and reservoirs into public parks that also function as stormwater catchments, setting a model for combining urban water management with quality of life improvements.
The Netherlands, renowned for flood control, employs strategic river flooding to protect vulnerable areas, balancing gray infrastructure with nature-based buffers (Kim, 2025). These examples illustrate how cities with different geographies and governance systems can tailor sponge city strategies to their unique contexts. Los Angeles, with its large volumes of stormwater runoff—estimated at 490,000 acre-feet annually—and aging impermeable flood control infrastructure, stands to benefit significantly from sponge city approaches.
The Safe Clean Water Program, approved as Measure W in 2018, allocates roughly $300 million annually from a tax on impermeable surfaces to fund stormwater capture projects aimed at collecting 98 billion gallons per year. However, progress has been slow due to bureaucratic hurdles, high project costs, and limited federal support, with only 30 acres of new green space added in the first three years (Kim, 2025).
Experts estimate that achieving the necessary scale will require investments around $50 billion, far exceeding current funding. These challenges highlight the need for streamlined permitting, innovative financing, and public-private partnerships to accelerate implementation. Combining green infrastructure with existing gray systems can enhance flood resilience while capturing local water supplies, reducing dependency on imported water.
L.A.’s experience underscores that sponge city solutions are not a panacea but require long-term commitment, cross-sector collaboration, and adaptive management to realize their full potential.
sponge city advocacy checklist urban water
Urban residents and stakeholders interested in advancing sponge city principles can take concrete steps to influence policy and project development. Advocates should consider the following actions to support resilient water infrastructure: ① Educate local officials and community groups about the benefits of sponge city models, including flood risk reduction, water quality improvement, and enhanced public spaces.
② Advocate for increased funding and streamlined permitting processes to reduce delays and costs associated with stormwater capture projects.
③ Encourage transparency and public participation in project planning to ensure community needs and environmental justice concerns are addressed.
④ Support pilot projects that demonstrate scalable, cost-effective sponge city interventions in diverse urban neighborhoods.
⑤ Promote partnerships between government agencies, private sector, and nonprofits to leverage resources and expertise.
⑥ Monitor and share data on project outcomes to build evidence supporting expanded adoption of green infrastructure.
⑦ Engage in long-term planning that integrates sponge city concepts with broader climate resilience and urban development goals. By taking these steps, communities can help shift urban water management toward more adaptive, nature-based solutions that protect cities from flooding while enhancing overall quality of life.
The successes seen in Bangkok, China, and elsewhere provide a proven blueprint for transforming vulnerable urban landscapes into resilient, vibrant places.
What aspects of sponge city design could be most impactful in your community?
What barriers exist locally to implementing nature-based water management projects?
(Source: Kim, Max. Should L.A.
look to ‘sponge cities’ to solve its flooding problem?
August 10, 2025)
