Abstract: This paper critically assesses the shortcomings of current climate crisis mitigation adaptation strategies, particularly the reliance on carbon reduction and gray infrastructure and proposes the Sponge Planet Model (SPM) that focuses on practical, scalable, water-based (thus community-based) solutions that aim to address the “tragedy of the commons” in carbon-focused climate mitigation strategies and singular-goal minded unsustainable gray infrastructure-centered adaptation strategies.
1. Introduction
The climate crisis presents an unprecedented challenge, characterized by rising global temperatures, increasing sea levels, extreme weather events, and a significant loss in biodiversity. Despite global efforts to reduce carbon emissions, the impacts of climate change continue to escalate, pointing to the necessity for more innovative solutions. The following four major challenges are critical areas requiring attention and action:
(1) The Inadequacy of Carbon-Centered Mitigation Strategies and the Need for a Holistic Approach: Current carbon-focused mitigation strategies fail to comprehensively tackle climate change, often missing out on nature-based solutions and the necessity to address socio-economic inequalities (von Braun et al., 2022). Furthermore, the reliance on carbon offsets has been criticized as mere “greenwashing,” enabling ongoing excessive consumption without substantial emission reductions, a concern highlighted by Pope Francis in his 2015 encyclical, Laudato si’ (Pope Francis, 2015). A combined approach of mitigation and adaptation is essential for sustainable results.
(2) Unsustainable and Short-Sighted Gray Infrastructure-Centered Adaptation: Traditional adaptation strategies often focus on gray infrastructure, such as concrete dams, seawalls, levees, and aqueducts, which typically provide short-term, singular solutions. While widely used, these gray infrastructure approaches have demonstrated limitations in delivering long-term resilience and sustainability. This raises the need for more integrated solutions, combining gray infrastructure with Nature-Based Solutions (NBS) to enhance effectiveness and sustainability (Seddon, 2020).
(3) Unfocused Nature-Based Solutions: Although Nature-Based Solutions (NBS) offer a sustainable approach to climate change adaptation, there is often a lack of focus on where investment in these solutions should be directed. This challenge calls for a more targeted approach to NBS, and how to create Nature-based Infrastructure, ensuring that the most effective strategies are prioritized for investment and implementation.
(4) Politics of No One’s Responsibility: The “tragedy of the commons” is a well-known concept that describes the dilemma of collective resource management. Climate change presents a similar challenge, where responsibility for addressing it is often unclear or dispersed among various stakeholders. This challenge involves finding ways to navigate the political landscape to ensure that collective action is taken, and that accountability is established among governments, corporations, and individuals.
As the global community confronts these escalating challenges, the necessity for a paradigm shift towards more holistic and inclusive approaches becomes evident. Strategies that prioritize ecosystem-based adaptation, sustainable agriculture, and comprehensive water management are essential to navigate the complexities of the climate crisis and secure a resilient future (Colls, Ash, and Ikkala,2009, Miller & Belton, 2014).
2. Towards a Unified Water-Driven Strategy for Nature-Based Solutions
In response to the challenges outlined, the author introduces a comprehensive and inclusive green-gray infrastructure solution called the Sponge Planet Model (SPM). This model shifts the focus from carbon to water as the key to building resilience against climate challenges. An evolution of the Sponge City concept, the SPM has been tested at scale in China and internationally (Yu et al., 2015; Yu, 2017; Gies, 2022; Peng et al., 2022). By positioning water at the heart of climate adaptation, the SPM integrates water management, ecological resilience, and urban infrastructure to address both climate change and its impacts. Drawing inspiration from natural systems and centuries of wisdom in managing irregular rainfall and monsoon climates, the SPM is based on three core principles: capturing rain where it falls, slowing water as it moves, and adjusting human activities and infrastructure to fluctuating water levels by creating more space for water on land. These principles are in stark contrast to conventional gray infrastructure solutions. Beyond mitigating the adverse effects of climate change, the SPM aims to restore biodiversity and natural habitats, offering a holistic solution to the environmental, social, and economic challenges posed by climate change.
2.1 Retaining Water at Its Source
The core of this principle lies in the strategic retention of water where it falls, advocating for a decentralized approach to water management. Unlike conventional methods that focus on concentrating water in dams and reservoirs – often leading to environmental degradation and a heightened risk of failure, as tragically demonstrated in recent events in South Brazil, Kenya, Pakistan, and even in the arid Libyan desert – SPM emphasizes the importance of porous landscapes and permeable land surface. These features allow rainwater to be absorbed and stored underground, replenishing aquifers and maintaining soil moisture. This approach champions a sustainable alternative, reducing the risks associated with large-scale water infrastructure while supporting local ecosystems.
(1) Conventional Solutions of Centralized System: Centralized water management systems have been the cornerstone of urban planning and agricultural practices for centuries. These systems, characterized by the concentration of water through dams, long-distance aqueducts, and the drainage of water via channels and impermeable surfaces, have supported the growth of cities and agricultural productivity. However, they also embody significant environmental and social costs, including habitat destruction, water over-extraction, and the displacement of communities (Kusena, 2022).
(2) Retaining Water at Its Source: Transitioning to a decentralized, nature-based system marks a critical paradigm shift in water resource management. This approach, inspired by the inherent properties of the SPM, emphasizes water retention at the source through porous landscapes, terraces, localized small pond systems, and distributed water management. Unlike conventional systems that expedite water runoff, these nature-based solutions slow down water flow, allowing for natural filtration and recharge of groundwater, thus enhancing the resilience of ecosystems to climate variability (Goodwin et al., 2023).
(3) Benefits of Retaining Water On-Site: The benefits of onsite rain retention extend far beyond water management. By mitigating the impacts of floods, drought, and fires, these practices contribute significantly to climate crisis adaptation. Ecologically, they support biodiversity and habitat restoration (O’Leary et al., 2023). Socially and economically, decentralized water management reduces infrastructure costs, lowers the risk of waterborne diseases, and promotes community engagement in sustainable practices(Pan et al., 2023). Moreover, the replenishment of aquifers and the enhancement of soil moisture through these methods secure food production and water supply in an era of unpredictable climate patterns (Razzaghi et al., 2020).
2.2 Slow Down Flow
Unlike traditional drainage systems that quickly divert water away from urban areas, often exacerbating downstream flooding and depleting valuable water resources, the SPM proposes the creation of meandering green-blue integrated waterways. These systems, designed to emulate natural river dynamics, not only enhance infiltration and reduce flooding risks but also foster biodiverse, multifunctional spaces beneficial to communities.
(1) Conventional Drainage Solutions in Addressing Floods: Traditional drainage systems, often referred to as ‘gray infrastructure,’ have long been the foundation of urban water management. These systems, which rely on concrete, pipes, and pumps, are engineered to rapidly divert water from built environments, reducing waterlogging and mitigating potential flood damage in urban areas. Components such as sewers, concrete channels, and storm drains are designed for efficient water conveyance, directing runoff swiftly to nearby water bodies. However, this approach presents notable limitations. It accelerates water flow, increasing the risk of downstream flooding, while also reducing groundwater recharge and disrupting natural hydrological cycles that eventually contribute significantly to sea level rise (Schultz, 2011; Wood and Hyndman, 2017, 2018). The environmental consequences are significant, contributing to ecosystem degradation, loss of biodiversity, and the urban heat island effect due to the prevalence of impermeable surfaces. In response, more sustainable alternatives, including nature-based solutions (NBS), are being developed globally (Fletcher et al., 2015; Well & Ludwig, 2021), with Sponge City emerging as a comprehensive approach (Yu et al., 2015).
(2) Slow Down Flow: A Paradigm Shift in Drainage Systems
The “Slow Down Flow” principle marks a significant departure from traditional drainage systems, which focus on rapidly channeling water away. This new approach prioritizes moderating water flow, encouraging infiltration, and replicating natural hydrological patterns. Features like meandering green-blue waterways and low weirs, as opposed to high dams, are key to this method, fostering interaction between vegetation and water to slow movement.
(3) The Importance of Slowing Down Flow
Slowing water flow is essential for flood risk reduction, as it decreases the destructive force of water and promotes more even distribution across landscapes, providing a sustainable alternative to traditional flood management methods (Qi et al., 2020; Peng et al., 2022). This strategy also promotes biodiversity by replicating natural river patterns, increasing habitat complexity, and supporting diverse species (Graziano et al., 2022; Yu, 2013). Furthermore, green-blue “sponge” systems improve water quality by filtering pollutants through natural filtration and bioremediation processes (Kumwimba et al., 2023).
Beyond the ecological and functional advantages, these spaces enhance residents’ well-being by increasing waterfront safety, offering recreational opportunities, improving urban aesthetics, and providing educational value to communities.
2.3 Embracing Water Surplus – Giving Water More Space
As climate-related water crises become more severe and frequent, it’s important to rethink traditional flood defense strategies. In the past, these methods focused on building strong barriers and complex systems to prevent flooding. However, these approaches have limitations and often harm the environment. This shows the need for a shift toward more sustainable solutions, like the “Embracing Water Surplus” principle, which offers a more adaptive and water-friendly way to manage floods.
(1) Conventional Defensive Solutions: Traditional flood defense strategies focus on physical barriers, such as flood walls and sea walls, coupled with extensive networks of pipes and pumps to manage urban and regional flooding. This ‘resistance’ approach seeks to hold back or quickly divert water away from vulnerable areas. While these methods can offer immediate protection, they often result in ecological damage and heightened vulnerability to climate change. In response, SPM (Sponge City Planning) advocates for a paradigm shift towards giving water more space and harnessing natural processes for water management. This includes adaptive designs in urban and building forms that minimize the need for defensive actions, promoting resilience through sustainable, ecological solutions.
(2) Embracing Water Surplus: SPM introduces a transformative approach to water management with its “Embrace Water Surplus” principle. This concept reimagines excess water as an opportunity rather than a problem, advocating for landscapes and infrastructures that leverage surplus water for ecological and urban benefits. Instead of relying solely on traditional barriers, SPM promotes strategies such as wetland restoration, flood parks, and utilizing available spaces to absorb and manage excess water. The approach emphasizes adaptive designs in buildings and infrastructure, incorporating features like elevated siting, raised thresholds for homes, and integrating skywalks in urban environments (Yu, Zhang, & Li, 2008; Yu,2021). These solutions aim to harmonize urban development with natural hydrological cycles, fostering resilience against flooding while enhancing urban livability.
(3) The Benefits of Embracing Water Surplus
Adopting nature-based solutions to embrace water surplus effectively mitigates flood risks and reduces the impact of extreme weather events. Additionally, it provides essential ecosystem services, including water purification, habitat creation, and carbon sequestration, all of which are vital for enhancing urban resilience and promoting public health (Oral et al., 2020; Lallemant et al., 2021; Penning et al., 2023).
Beyond ecological advantages, the development of flood parks and green spaces yields significant socioeconomic benefits. These include increased recreational opportunities, improved mental health, and higher property values, which together contribute to the creation of healthier and more vibrant communities (Kolimenakis et al., 2021). These multifunctional spaces not only strengthen environmental sustainability but also foster social well-being and economic growth.
2. Demonstrating Sponge Planet
For the past 30 years, the author and his team have tested the Sponge Planet Model (SPM) in over 250 Chinese cities, implementing more than 1,000 projects across various scales, from entire watersheds spanning hundreds of square kilometers to urban sponge parks covering hectares. These initiatives have been proven successful, with significant performance results (Saunders, 2012; Yu et al., 2015, Yu, 2019; see: www.turenscape.com). The following three examples demonstrate this success, each illustrating one of the core SPM principles.
(1) Retention: Retaining water at Its Source
Bangkok Benjakitti Forest Park morphs from industrial to ecological marvel, showcasing “Principle 1: Retention” at its core. The park’s cut-and-fill strategy forms porous landscape made of wetlands and islets, holding 200,000 cubic meters of stormwater, buffering the city against monsoon impacts. This transformation not only curtails flooding but fosters biodiversity, proving urban spaces can harmoniously coexist with nature-based water solutions, enhancing urban resilience and community spaces (Yu and Wang, 2023).
(2) Slow Down: Managing Urban Water Flows
Liupanshui Minhu Wetland exemplifies “Principle 2: Slow Down Flow,” transforming a polluted and channelized drain into a thriving, clean waterway. By reintroducing wetlands and low weirs, it combats flooding and pollution, weaving the community back into the urban fabric with green spaces and recovered native habitats. Its approach demonstrates the synergy between civil engineering and ecological design, serving as a benchmark for urban waterway revival (Yu, 2019).
(3) Embracing Flood and Mitigating Drought in the Urban Center
Sanya, on southern China’s Hainan Island, has long been impacted by severe flooding and urban inundation due to the monsoon climate and global climate change. These challenges, along with pollution and habitat loss, made the city an ideal testing ground for SPM. Dong’an Wetland has since become one of the most significant multifunctional demonstration projects of China’s nationwide sponge city initiative. Inspired by ancient farming wisdom, the project was completed swiftly, cost-effectively, and designed for large-scale replication. The green sponge system consists of hundreds of pond-dykes, forested islands, and a flood-adaptive network of skywalks above the canopy and boardwalks below it. This water-driven holistic solution addresses numerous climate challenges, including flooding, drought, biodiversity loss, and urban heat. Additionally, it has spurred economic development, increasing surrounding property values by 400% and reducing temperatures by 8°C under the canopy (Yu, 2021).
3. Conclusion: Towards a Holistic and Unified, Water-Driven Paradigm in Nature-Based Climate Solutions
The Sponge Planet Model (SPM) offers a holistic, nature-based approach that is vital for addressing the climate crisis through integrated water management strategies. It challenges carbon-centric mitigation and conventional gray infrastructure adaptation solutions by prioritizing water-centric methods that address both mitigation and adaptation. SPM enhances biodiversity while providing socio-economic benefits. It promotes a shift from unsustainable gray infrastructure to more sustainable green-gray systems, focusing on water retention, slow flow, and the use of surplus water, making nature-based solutions more precise and impactful. By fostering interdisciplinary collaboration and advocating for a global transition from gray to green infrastructure, SPM builds strong connections with communities, offering a resilient and sustainable future. This approach reimagines our relationship with the environment, advocating for innovative, territory-based solutions that address climate challenges through practical water resource management.
Implementing SPM principles presents challenges like policy integration, interdisciplinary collaboration, long-term planning, community engagement, funding, and, most importantly, shifting from a carbon-dominant to a pragmatic down to earth, water-driven NbS approach – while sustaining carbon reduction efforts. Key priorities include interdisciplinary research, supportive NbS policies, and increased community participation in decision-making. These steps will promote water-driven climate strategies that integrate ecological restoration and biodiversity enhancement at global, national, regional, and local scales. The ultimate goal is to restore a “Sponge Planet” through holistic, water-centric design to tackle global water mismanagement.
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