“Sponge City” Viability: A Conceptual Framework and Review of Reviews

1. Introduction

China is confronted with a unique water crisis, characterized by coexisting urban flooding, water scarcity, and water pollution [1]. Flood risk is a pressing stormwater management issue in many Chinese cities, driven by rapid urbanization, land-use change, and accelerated socio-economic development [2]. Studies reveal that nearly 98% of the country’s 654 leading cities have problems with flooding and waterlogging due to rapid urban growth in recent years, encroaching floodplains with impermeable concrete surfaces [3,4,5]. Climate change, along with intensified human activities, has led to more frequent flooding in regions like the Yangtze River and the Huai River Basins. Conversely, precipitation in the north and northeast regions has declined since 1970, leading to arid conditions. Certain areas have experienced severe droughts in recent years [6].

To solve the urban stormwater problems, the “Sponge City” (SC) concept was first proposed by Chinese scholars in the early 2010s [7]. Chinese President Xi Jinping endorsed the SC idea during the Central Government Conference on Urbanization in 2013 [8]. In 2014, China initiated a nationwide SC campaign [9], incorporating low-impact development (LID) principles into SC policies [7] . Since then, a series of policies and guidelines have been introduced to reinforce and advance SC implementation nationwide.

In this manuscript, Sponge City is defined as an ambitious planning policy and design practice in China that relies primarily on nature-based solutions to manage stormwater amid climate change and rapid urbanization. Additional definitions of SC-related terms are provided in Appendix A: Sponge City Key Term Glossary.

The SC practice in China is not merely a practice; it is a transformative movement in urban planning. The massive scale and the amount of effort the Chinese government has put into it are unprecedented. Between 2015 and 2016, 30 cities were selected as pilot cities from 500 applications [10], receiving substantial government subsidies of USD 6.4 billion. The national goal is to implement the SC concept in 20% of built urban areas by 2020, with a major increase to 80% by 2030 [11]. Building on the momentum of the ongoing pilot city programs, more than 600 cities across China have been mobilized to achieve the ambitious goal within a short timeline [12]. The estimated construction cost for SC is between 15 and 22.5 million USD per square kilometer, with a total expenditure of 1.5 trillion USD [1]. After over a decade of practice, the initiative has evolved into a common practice, deeply ingrained in urban design schemes across the country [13].

China’s SC policy and its practical implementation have gained significant attention [6,14] with numerous scholars engaging in discussions and research, especially in the fields of environmental sciences. This has resulted in thousands of publications across major academic databases in Chinese and English. Because of the vast literature on the SC topic, navigating and synthesizing this extensive body of work poses a significant challenge.

To address the complexity and breadth of the literature on China’s SC initiative, this study adopts a review of reviews approach. The process of identifying and appraising published reviews allows researchers to assess the quality of the existing evidence, synthesize and contrast the review findings, and assess the strength of the conclusions reached [15]. Modeled after a published review of reviews journal article by Javaid et al. [16], this study also adopts a proposed framework to assess SC viability in China. The framework comprises six key dimensions (see Section 2. Framework and Figure 1), which serve as the analytical lens for organizing and synthesizing findings from existing review studies. This approach enables a systematic extraction and evaluation of evidence across diverse thematic areas relevant to SC viability. The following research questions (RQs) guide this review of reviews: 1) How does the existing review literature address the six dimensions of SC viability in China? 2) What challenges and opportunities within these six dimensions emerged from the review literature? and 3) What research needs might be important considerations to guide future SC scholarship and implementation?

2. Framework

It is crucial to have a coherent framework that highlights the key influencing factors that affect SC viability in China. SC planning and practice can be placed under the broader umbrella of sustainable development, defined as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs” by the Brundtland Commission of the United Nations in 1987 [17]. In the mid-1990s, John Elkington introduced the “Triple Bottom Line” framework, emphasizing three dimensions of sustainability: people, planet, and profit (3Ps) [18]. The framework involves integrating environmental considerations into every aspect of social, political, and economic activities. This echoes related constructs, including the three pillars of sustainability [17] and the “planners triangle” [19], both of which highlight the importance of addressing environmental, economic, and social equity (3Es) considerations in sustainable urban planning.

This study draws on these precedents to investigate the viability of the SC initiative in China, a planning policy and practice centered on stormwater management. It adopts a novel conceptual framework to assess SC viability (see Figure 1), which was first introduced by the authors and applied through a recent qualitative interview study with 30 SC practitioners and domain experts [20]. Building on that work, the present study further elaborates this framework by applying it to the broader body of SC scholarship.

The benefits of sustainable urban stormwater management extend well beyond flood control. SC projects can generate a wide range of ecosystem services, including improved water quality, groundwater recharge, and enhanced urban biodiversity [21]. Equally important are the social benefits it can provide, such as promoting public health, enriching urban aesthetics, expanding cultural and recreational opportunities, and fostering inclusive community development. Realizing these diverse potentials requires stormwater interventions to adopt a multidimensional lens, one that accounts not only for environmental factors but also for spatial and social dimensions. Within the proposed conceptual framework, four subdimensions are identified under Elkington’s “people” category [18]: Governance, Civic Engagement, Urban Form, and Human Wellbeing. These sub-dimensions warrant focused, discrete attention because each represents a distinct pathway through which SC implementation interacts with human experience, institutional processes, and the social fabric of urban environments. Together, they illuminate how policy, participation, spatial design, and lived experience may be shaped by the SC initiative.

Governance is central to the success of SC projects in China, as it addresses the coordination of policies and allocation of resources across sectors [22]. Importantly, the centralized, top-down system of governance in China can serve as either a critical enabler or a barrier to viable SC planning and implementation [7].

Civic Engagement is an essential consideration because it ensures that local communities are actively involved in the planning, design, and maintenance of SC infrastructure. Bottom-up participatory approaches cultivate a sense of ownership and pride in the community. It also makes people more aware of water conservation, sustainable practices, and environmental stewardship [23] thereby enhancing long-term sustainability.

Urban Form plays a critical role in the viability of SC interventions, as urban development can significantly alter runoff patterns by increasing impervious surface coverage [24]. The resulting urban form can significantly affect flood vulnerability [25]. As such, effective SC projects need to take urban morphology into account to not only bolster flood resilience but also enhance urban aesthetics, livability, and social cohesion.

Last but not least, human health and wellbeing are important factors in assessing SC viability. The urban ecological environment plays a vital role in promoting positive emotions, reducing stress, and enhancing overall population health [26]. Sponge Cities that incorporate green spaces and water-sensitive urban design can also provide therapeutic benefits, significantly improving both mental and physical wellbeing [27]. This co-benefit is crucial for evaluating the broader viability of such interventions beyond technical performance.

From these considerations, six key dimensions of SC viability form a coherent conceptual framework, embracing the 3 Ps [18], including “planet”, “profit”, and four subcategories in the “people” dimension that encompass Governance, Civic Engagement, Human Wellbeing, and Urban Form. As noted in Tang et al. [20], these dimensions are interrelated to one another rather than being mutually exclusive, and are critical to SC theory and practice.

3. Methodology

This study adopts a review of reviews approach, informed by the established systematic review of reviews methodology in healthcare [15] and a recent review of reviews publication in sustainability research [16]. Following the PRISMA protocol [28], the methodology was designed to ensure transparency, rigor, and thematic breadth. The review process embraced four key steps. First, a multi-stage search and screening process was carried out across multiple academic databases using the PRISMA protocol. Second, keyword co-occurrence visualization was carried out using VOSviewer software to show patterns and research emphasis in the collected review literature. Third, each collected review was assessed for thematic relevance to the six dimensions in the proposed framework (see 2. Framework and Figure 1) using a simplified 0-3 Likert scale rating system, with emphasis on the depth of discussion and thematic alignment. Finally, a thematic review was carried out in three stages: 1) evaluating each review article’s contributions to specific dimensions; 2) conducting targeted supplementary reviews where gaps were identified; and 3) synthesizing findings using a narrative review approach to identify cross-cutting challenges and opportunities in six dimensions of SC viability in China. This multi-step approach enabled a comprehensive and comparative understanding of the scholarly work on SC viability in China.

To provide greater analytical depth, the final set of review articles was examined using an inductive (a posteriori) thematic coding process. Guided by the conceptual framework (see Section 2. Framework), patterns and concepts emerged iteratively from the texts related to the six dimensions of SC viability (Environment, Economy, Governance, Urban Form, Civic Engagement, and Human Wellbeing). Key themes of challenges and opportunities in each dimension were refined through constant comparison across articles, with studies coded across multiple dimensions where appropriate. This inductive approach, anchored within the overarching conceptual framework, allowed the analysis to remain both empirically grounded and analytically structured. To enhance analytical rigor and reliability, the inductively generated themes were reviewed and discussed among the research team to reach shared agreement on theme definitions and implications.

3.1. PRISMA Protocol

The literature search was conducted on July 22, 2025, using two major academic databases: Web of Science (WoS) and Scopus. Searches in both databases employed the truncated terms “Sponge Cit” AND “Chin”** to capture all relevant variations (e.g.,, Sponge City/Cities, China/Chinese), with capitalization not affecting results. The initial search yielded 1,943 records from WoS and 755 records from Scopus, encompassing journal articles, review papers, conference proceedings, book chapters, and other document types across four languages.

The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines [29] were followed to ensure clarity, transparency, and rigor in the literature review and synthesis. Because this study adopts a review-of-reviews approach, only review articles were retained. Bibliographic records were exported to Zotero, where duplicates were identified and manually removed, resulting in 91 unique review articles (83 in English, 8 in Chinese).

Titles and abstracts were then screened to exclude studies unrelated to the viability of SC planning and practice in China, leaving 73 articles for full-text assessment. Following full-text review, 23 articles were excluded for insufficient relevance, yielding a final sample of 50 review articles (44 in English, 6 in Chinese) for analysis and synthesis. The selection process is summarized in the Adapted PRISMA Flow Diagram (Figure 2).

3.2. Keyword Co-Occurrence Visualization

To explore thematic relationships within the selected literature, a keyword co-occurrence visualization was generated using VOSviewer, a software tool for visualizing bibliometric networks [30]. Keywords were extracted from the titles and abstracts of the selected 50 review articles published between 2017 and 2025. VOSviewer was used to generate a term co-occurrence map from author keywords. Keywords appearing at least three times were included in the analysis. The software clustered related keywords and positioned them according to the strength of their co-occurrence relationships, with more strongly associated keywords located closer together.

Figure 3 shows the resulting network of 124 keywords that met the minimum occurrence threshold, drawn from a total of 1,050 keywords identified in the literature. In the network, nodes represent keywords and links represent co-occurrence relationships between them. The more often two terms appear together, the closer they are to each other on the map. Different colors indicate different clusters of related terms identified by VOSviewer. The top six keywords with the highest co-occurrence in all titles and abstracts in the review article collection were “water management,” “performance,” “floods”, “climate change,” “low impact development,” and “green infrastructure”. Terms like “Sponge City”, “China”, and other less informative, generic terms were excluded to enhance clarity and relevance.

3.3. Rating of Thematic Relevance

The Likert scale, which was first introduced by Rensis Likert in 1932 [31], served as the basis for ranking the thematic relevance in this study. Likert’s seminal work, “A Technique for the Measurement of Attitudes,” established the popular 5-point scale framework for assessing perceptions and attitudes. To assess the thematic relevance linking each review article to the six framework dimensions, a simplified Likert scale rating system with a range of 0 to 3 was adopted:

Table 1. Likert scale rating system of thematic relevance.

Scale	Ranking	Description
0	Not relevant	Not mentioned at all.
1	Weakly relevant	The dimension is mentioned with little explanation or indirect significance.
2	Moderately relevant	The dimension is explained with some interpretation or supporting data.
3	highly relevant	The dimension is the main focus of the review and is supported by thorough analysis and solid data.

Table 1. Likert scale rating system of thematic relevance.

Scale	Ranking	Description
0	Not relevant	Not mentioned at all.
1	Weakly relevant	The dimension is mentioned with little explanation or indirect significance.
2	Moderately relevant	The dimension is explained with some interpretation or supporting data.
3	highly relevant	The dimension is the main focus of the review and is supported by thorough analysis and solid data.

These ratings reflect the degree to which each review provides substantive insights into a specific dimension. To ensure consistency and reliability of the rating, the two lead authors respectively coded five of the selected review articles and arrived at similar ratings; the remaining articles were rated by the lead author. Author interpretations, study consistency, and expert judgment all influenced the evaluations, which should be understood as an organized yet interpretive assessment.

3.4. Thematic Review

The thematic review followed several steps to assess SC viability across the six dimensions of the conceptual framework. Using a simplified 0–3 Likert scale, each review article was evaluated through full-text analysis for its relevance to the corresponding dimensions. When necessary, original studies cited in narrative reviews were also examined.

Key challenges and opportunities are summarized in the Results section and analyzed in the Discussion section. It entailed synthesizing the findings of all selected review papers to identify common themes, gaps, and points of divergence. This synthesis also sought to identify cross-cutting issues that may not be apparent in individual assessments by drawing upon ideas from research across the six dimensions.

4. Results

This section highlights the key findings of this review of reviews study by examining how scholarship on China’s Sponge City (SC) initiative aligns with the six dimensions of the SC viability framework: Environment, Economy, Governance, Civic Engagement, Urban Form, and Human Wellbeing. For each dimension, the corresponding subsection foregrounds review papers rated as “highly relevant” in the thematic assessment, followed by those classified as “moderately” or “weakly relevant.” Each subsection then systematically identifies the key challenges and opportunities associated with that dimension in the literature. Bar charts in each subsection are used to visualize the frequency of themes and are color-coded to align with the conceptual framework shown in Figure 1. The sequence of this subsection is organized based on the weighted relevance scale of the thematic rating system in Table 2. The Environmental dimension ranks as the primary focus of the literature (2.9/3), followed by Urban Form (1.4/3), Governance (1.3/3), Economy (1.2/3), Human Wellbeing (0.8/3), and Civic Engagement (0.6/3).

Figure 4. Weighted scale of thematic relevance.

Figure 4. Weighted scale of thematic relevance.

4.1. Challenges and Opportunities across the Six Dimensions of the Framework

4.1.1. The Environmental Dimension

Of the 50 review articles examined, 46 were rated highly relevant (scale = 3) and four moderately relevant (scale = 2) to the Environmental dimension. The total relevance score was calculated as (46 × 3) + (4 × 2) = 146. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 2.9 on a 0–3 scale. Following an in-depth review, key themes were identified.

Figure 5 and Figure 6 present the major environmental challenges and opportunities that influence SC viability, along with their frequencies of occurrence across the reviewed articles.

• Environment: Challenges

1)

Systemic co-occurrence of urban water problems

China faces a unique water crisis as urban flooding, water scarcity, and water pollution coexist [1], interacting with each other and elevating environmental risk. Stormwater management is much more complicated than tackling any single urban water issue. Since sponge measures must function within already strained hydrologic and ecological systems, these systemic pressures directly impact SC viability. As Nguyen et al. [32] (p. 12) note, “a comprehensive understanding of urban water systems is extremely important to prevent major problems such as flooding, water pollution and water shortages.”

2)

Extreme weather exceeding system capacity

Intensified climate change has triggered a global spike in extreme rainfall events, substantially increasing the risk of urban floods [33]. Studies show that SC strategies may reduce flooding during minor events but fail under major ones [34]. “As the rainfall return period increases, the effectiveness of LID facilities in mitigating urban flooding diminishes… as the schemes gradually reach their maximum handling capacity” [35] (p. 9). Without adequate storage, conveyance, and flood-control capacity, environmental risk persists, limiting the effectiveness and long-term sustainability of SC interventions.

3)

Geographic heterogeneity

Given China’s diverse geographic conditions, from tropical areas in the south to sub-arctic zones in the north, and alpine conditions in the Tibetan regions, it is difficult to develop a universal plan for all cities [1]. Soil and topographic differences further constrain infiltration potential [36], and cold, wet regions face performance losses from freeze–thaw cycles and biological growth in permeable materials [37]. Without local calibration to these varied biophysical contexts, SC measures risk underperforming or failing. As summarized by Nguyen et al. [38] (p. 11), “some physical challenges, including climate, soil and geographical conditions are barriers to implementing a successful Sponge City.”

5)

Environmental “disservices” & bio-physical side effects

Environmental “disservices” can hinder SC viability when poorly performing measures generate new environmental burdens. Review literature reveals that certain SC facilities may increase nutrient loading or act as pollutant sinks, allowing stormwater to mobilize phosphorus, heavy metals, and other contaminants into soils, wetlands, or storage systems (e.g., [39,40]). As noted by Chikhi et al. [23] (p. 2), “the overuse of infiltration-based facilities can lead to substantial contamination of subsurface water, allowing the runoff pollutants to reach the underground water, allowing the runoff pollutants to reach the underground water” (citing [22]). Scholars also point out that green roofs may become pollutant sources with the potential to leach into runoff [39]. Additional unintended effects, such as algae and bacterial growth on permeable pavements in humid climates [37] or heightened mosquito breeding in stagnant or clogged areas [41], undermine ecological performance and increase maintenance demands.

• Environment: Opportunities

1)

Improve water quality through source control and ecological treatment

Sponge City systems can enhance environmental performance by capturing and treating stormwater at the source, thereby intercepting pollutants and reducing non-point contamination [41,42]. As Huang et al. [43] (p.1.) emphasize, SC construction is “an ideal approach to mitigate the degradation of urban water environments.” Rain gardens, in particular, can “infiltrate rainwater, intercept pollution sources, and optimize reuse” [42] (pp 1-2), while permeable pavements can increase rainwater infiltration and purify surface runoff [37]. Moreover, “constructed wetlands (CWs) can not only purify water quality, but also store and regulate rainwater” [44] (p. 1). Through these hydrologic purification processes, SC measures can restore natural hydrological pathways and improve downstream water quality, supporting long-term environmental sustainability.

2)

Enhance climate resilience

By attenuating flood peaks and moderating microclimates, SC interventions can function as climate-resilient infrastructure, enhancing urban resilience to extreme rainfall and heat, especially when deployed at scale and paired with upgraded drainage and other nature-based solutions. Studies show that such measures can help control runoff, mitigate urban flooding, and strengthen disaster prevention [33]. As Yin et al. [36] (p. 12) note, SC measures can “significantly reduce runoff volume, improve runoff quality, alleviate heat island effect, and increase groundwater recharge.” Together, these environmental benefits can support more reliable climate adaptation and strengthen overall SC viability.

3)

Restoring urban ecological functions

A key environmental opportunity for strengthening SC viability lies in the capacity of nature-based, green stormwater infrastructure (GSI) to restore degraded urban ecological processes. GSI measures, such as wetlands, green swales, permeable surfaces, bioretention systems, and expanded green networks, can enhance infiltration, support groundwater recharge, improve stormwater purification, and stabilize local microclimates [34,45]. Building on these strategies, SC approaches further promote ecological renewal by restoring habitat structure, increasing biodiversity, and reestablishing water–soil–plant interactions. They can also help address hydro-meteorological phenomena, enabling cities to recover ecological capacity and strengthen long-term environmental performance [46].

4)

Holistic management of urban water systems

By treating stormwater as a resource rather than a threat, the review literature suggests that SC strategies can potentially address multiple co-occurring water challenges, including urban flooding, water scarcity, pollution, and ecological degradation [47,48]. Urban rainwater harvesting and source-control measures are integrated solutions that combine storage, infiltration, purification, and reuse to enhance system resilience and reduce pressures on the urban water cycle [1,49]. As Zhou et al. [48] (p. 1) note, rainwater harvesting offers “an effective approach to solve comprehensive urban water problems”, while Chen and Guo [47] highlight its potential to mitigate water scarcity. These approaches, together with holistic planning and design, can help SC address interrelated water concerns more effectively and sustainably.

4.1.2. The Urban Form Dimension

Of the 50 review articles examined, five were rated highly relevant (scale = 3), 15 moderately relevant (scale = 2), and 23 weakly relevant (scale = 1) to the Urban Form dimension. The total relevance score was calculated as (5 × 3) + (15 × 2) + (23 x 1) = 68. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 1.4 on a 0–3 scale. A review of these articles further revealed key themes related to both the challenges and opportunities of Urban Form in the context of SC viability. Figure 7 and Figure 8 illustrate the key themes of urban form-related challenges and opportunities influencing SC viability, along with their respective frequencies of mention in the identified review articles.

• Urban Form: Challenges

1)

Scale mismatch and fragmented implementation

Sponge City projects in China are often implemented as fragmented, site-scale interventions rather than as part of an integrated water system with hydrological connectivity. As Jiang et al. [4] (p. 139) observe, “the initiatives across pilot cities are largely conceived and implemented as independent, standalone activities rather than systematically organized, integrated components of a program”. Many interventions prioritize local surface permeability while overlooking hydrological linkages between neighboring watersheds [23]. Tohis scale mismatch and fragmentation limit cumulative benefits and undermine system-level flood resilience.

2)

High-density land use and physical constraints

High-density urban land use with limited open space as well as physical constraints, such as unfavorable soils, steep slopes, and high groundwater tables, significantly limit the feasibility and effectiveness of sponge facilities. As Yin et al. [36] (p. 7) highlight, “rapid developments… have encroached into floodplains, lowlands, and lakeshore areas.” In built cities, sponge strategies are often downsized or excluded due to space constraints. Many older neighborhoods dominated by impervious surfaces lack the flexibility for retrofitting. J. Han et al.[7] (p. 1312) further observe, “China has a large number of urban communities that are impractical for direct renovation or reconstruction as sponge cities”.

3)

Facility degradation and loss of function

Many SC facilities, such as permeable pavements, bioretention cells, and green roofs, experience performance decline over time. Without regular inspection and maintenance, these systems are vulnerable to clogging, material aging, and vegetation decline [4,50]. In dense urban settings, inadequate upkeep can quickly reduce infiltration and hydraulic efficiency, causing well-designed SC interventions to underperform or fail. As Li and Zhang [51] (p. 5) emphasize, “regular inspection and maintenance are necessary…, as the clogging and aging of measures can reduce the runoff control capacity.”

4)

Uneven spatial distribution of SC facilities

Sponge City facilities are disproportionately concentrated in parks and large public open spaces, leaving streets, residential blocks, corridors, and blue networks overlooked. This imbalance in SC types limits their cumulative hydrological impact across the urban landscape. As N. anHanHan et al. [33] (p. 13) note, “nearly half of the reviewed studies (48.5%) concentrate on parks, whereas other forms of green and blue infrastructure… are comparatively underrepresented”. Kumar et al. [1] (p. 21) further comment, “planning of sponge cities requires several LIDs to be located in private properties… hard to convince them (property owners) to allocate considerable spaces.”

• Urban Form: Opportunities

1)

Multiple functions and benefits

SC measures embedded in urban landscapes, such as wetlands, rain gardens, permeable pavements, and green roofs, are widely recognized for their ability to deliver multiple benefits simultaneously [37,49,52]. Rather than functioning solely as drainage facilities, sponge facilities can be designed as integral components of public space and urban life, enhancing livability while addressing stormwater challenges. For example, they can support cultural ecosystem services (CES), such as recreation, aesthetics, identity, and spiritual well-being, as noted by N. Han et al. [33].

2)

Improving the water cycle through place-based design

Urban surface redesign enables runoff reduction, peak-flow attenuation, water purification, and groundwater recharge, reinforcing the role of urban form in regulating hydrological processes. The review literature shows that the hydrological performance of SC interventions depends on how design strategies respond to local conditions, particularly the physical configuration and material properties of urban surfaces (e.g., [36,44]). For example, Fang et al. [53] note that permeable pavement can effectively regulate urban rainwater runoff by promoting infiltration and storage, while Jiang et al. [54] identify LID bioretention systems as one of the key measures in SC construction, particularly when adapted to local conditions.

3)

Connectivity through systematic spatial planning

Sponge City viability can be greatly enhanced when sponge infrastructure is planned as part of an integrated blue–green network across multiple spatial scales. These elements can strengthen hydrological and ecological connectivity from the site to the city and, potentially, to the watershed level. The literature emphasizes that these benefits depend on systematic spatial planning and coordinated implementation, aligning urban form, hydrology, and infrastructure to move beyond fragmented approaches toward integrated urban water resilience (e.g., [49,55]). As stated by Li and Zhang [51], systems thinking can “enhance the connectivity between source–community–region watershed scales.”

4)

Retrofitting urban landscapes

Sponge City projects provide an opportunity to integrate green and gray infrastructures [56,57]. Rather than replacing conventional drainage systems, SC elements can be retrofitted into established urban fabrics, allowing already built-out cities to enhance stormwater performance without large-scale demolition or additional land acquisition [34,58]. J. Han et al. [7] (pp. 14-15) further note that “retrofitting existing urban communities with Sponge City features is a common practice in pilot areas.”

4.1.3. The Governance Dimension

Of the 50 review articles examined, nine were rated highly relevant (scale = 3), 14 moderately relevant (scale = 2), and eight weakly relevant (scale = 1) to the Governance dimension. The total relevance score was calculated as (9x3) + (14x2) + (8×1) = 63. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 1.3 on a 0–3 scale. Following an in-depth review, key themes were identified. Figure 9 and Figure 10 present the major governance-related challenges and opportunities influencing SC viability, along with their frequencies of occurrence across the reviewed articles.

• Governance: Challenges

1)

Institutional fragmentation and insufficient coordination

Sponge City development in China is shaped by a policy-driven planning system dictated by a centralized governance structure [33]. However, implementation is frequently fragmented across agencies, particularly due to “lack of integration between urban land policy and urban water management” as stated by Nguyen et al. [38] (p. 160). This is echoed by N. Han et al. [33] (p. 19), who note that practical implementation barriers include “fragmented responsibilities, limited cross-sectoral coordination, and bureaucratic inertia” (citing [59,60]). All of these limit effective coordination and integrated decision-making, undermining system-level outcomes.

2)

Weak legal basis and limited policy enforcement

While China’s SC Initiative is a major national policy, there is currently no national-level legislation specifically governing its implementation. The program operates primarily through central government guidelines, administrative notices, and technical standards rather than a formal law passed by the national legislature [3]. “The lack of legislation from the central government is one of the major factors that hinder the nationwide implementation of SCP in China” [3] (p. 7). As a result, SC implementation remains uneven across cities and regions, limiting scalability and long-term commitment.

3)

One-size-fits-all standards lacking local adaptability

Uniform national standards and guidelines do not account for local variations in climate, soil, groundwater, terrain, and urban form. This lack of place-based adaptability frequently leads to poor site selection and design, decreased efficacy, and implementation barriers at the local level. As Qi et al. [46] (p. 11) note, the SC pilot cities “are located in contrasting geographical areas, with terrains ranging from coastal plains to lowlands and mountains, and regional climates ranging from tropical to temperate forest, which complicates the development of overarching guidance” (citing [61]).

4)

Policy inconsistency and misalignment across governance levels

Policy conflicts and misalignment between national and local priorities create ambiguities and inefficiencies, weakening coherence and effectiveness across governance levels. According to Yin et al. [57] (p. 12), “conflicts still exist among many current policies issued by different ministries.” Policy inconsistency, such as “inadequate building codes on infrastructure and land-use planning” [34] (p. 5), disrupts alignment between national guidance and local practice, affecting coordinated execution.

• Governance: Opportunities

1)

Lateral integration and cross-sectoral governance

Sponge City viability can be enhanced by shifting toward integrated, cross-sectoral governance that connects stormwater management with land-use planning, environmental protection, and urban livability improvement, particularly through the coordination between land use planning, construction methods, and SC implementation. Such integration can help overcome fragmented responsibilities and enable system-level coordination across disciplines and administrative sectors. For example, C. Shi et al. [55] suggest that the multidisciplinary approach can integrate water management with spatial planning.

2)

Strengthening legislation and policy instruments

Relevant literature suggests that governance opportunities arise from establishing clearer laws, regulations, and mandatory policy instruments to support SC implementation (e.g., [3,52]). As J. Han et al. [7] (p. 13) advocate, “more laws and regulations can be established to facilitate the sponge city development.” Stronger legal foundations can improve enforcement, accountability, and long-term commitment, helping move SC initiatives beyond pilot-based experimentation toward institutionalized practice.

3)

Context-sensitive and locally adaptive standards

Literature reveals that a crucial governance opportunity is to replace strict, universal standards with flexible, place-based guidelines that address local climatic, hydrological, geological, and urban form constraints (e.g., [42,62]). Yin et al. [36] (p. 2) assert that the SC planning and design “should be based on the differences in the city’s climate characteristics, soil types, and zoning”. Locally adapted standards can enhance the feasibility, performance, and relevance of SC measurements across a wide range of urban conditions under climate change.

4)

Policy alignment across governance levels

Scholars emphasize the importance of policy alignment across ministries and levels of government. In particular, effective coordination among central, provincial, and local governments is essential for achieving national SC goals set for 2030 [1,56]. As Nguyen et al. [38] (p. 10) note, “the close cooperation of various levels of government administration is a vital factor for successful implementation of Sponge City.”

4.1.4. The Economic Dimension

Of the 50 review articles examined, four were rated highly relevant (scale = 3), 16 moderately relevant (scale = 2), and 17 weakly relevant (scale = 1) to the economic dimension. The total relevance score was calculated as (4x3) + (16x2) + (17×1) = 61. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 1.2 on a 0–3 scale. Following an in-depth review, key themes were identified. Figure 11 and Figure 12 present the key economic-related challenges and opportunities influencing SC viability, along with their frequencies of occurrence across the reviewed articles.

• Economy: Challenge

1)

High investment costs & fiscal pressure

Sponge City implementation necessitates substantial upfront capital investment for stormwater management system integration and construction costs. Multiple reviews, including Jiang et al. [4] and Luo et al. [42], support the findings of Li and Zhang [51] (p. 1643), “high initial construction costs and limited fiscal capacity of local governments remain major constraints for widespread implementation of sponge city projects.” Nguyen et al. [32] further underscore, “the Sponge City model requires substantial investment costs… the costs involved might exceed the value of the output.”

2)

Uncertain economic benefits & cost-benefit valuation

Several reviews report difficulty in monetizing SC benefits, such as ecosystem services, flood risk reduction, and climate resilience [22,32]. This is partially due to the unclear long-term scope and the spatially diffuse pattern of SC interventions. Benefits such as cultural ecosystem services are indirect and also difficult to monetize [33]. Additionally, life-cycle cost analysis is lacking. As Xu et al. [10] (p. 1109) note, “most studies focus on hydrological performance, while the economic benefits of low-impact development practices are difficult to quantify and remain highly uncertain.”

3)

Limited private-sector participation & financing mechanisms

Reviews highlight that weak public–private partnerships (PPPs) deter private investment, leaving SC initiatives reliant on insufficient public funding and creating a significant financing gap that local governments cannot address alone. As Jia et al. [58] (p. 21) note, “the lack of attractive profit mechanisms and clear return pathways has significantly reduced private sector participation in sponge city projects”. This challenge persisted in subsequent years, as Chan et al. [63] (p. 5) observe that “current financing mechanisms are insufficient to mobilize large-scale private capital for sponge city development.”

4)

Insufficient operation & maintenance (O&M) funding

Long-term O&M is frequently underestimated or excluded at the planning stage. Reviews emphasize that inadequate O&M funding undermines performance, reduces lifecycle cost-effectiveness, and threatens SC sustainability. As Lu et al. [45] (p. 578) discuss in their study of roadside green swales in China’s SC implementations, “one of the major challenges faced is sustaining funds for ongoing maintenance after swale construction.” Yin et al. [36] (p. 11) further emphasize that “without regular inspection and maintenance, the runoff control capacity… would be undoubtedly affected.”

• Economy: Opportunities

1)

Life-cycle efficiency and long-term savings

Several reviews, including articles by Nguyen et al. [38] and Chikhi et al. [23], suggest that although SC construction involves a higher initial investment, it can significantly lower long-term costs by reducing flood damage costs and infrastructure maintenance expenses. Xu et al. [10] (p. 1110) further emphasize that, “life-cycle cost analysis shows that low-impact development practices can achieve better economic performance over the long term compared with conventional grey infrastructure.”

2)

Economic valuation of ecosystem services and co-benefits

Sponge City systems can support multiple ecosystem services, including water purification, urban cooling, biodiversity enhancement, and recreational benefits, which can be incorporated into economic valuations to broaden the investment rationale beyond single-function flood control. Several review studies indicate that ecosystem services can be quantified using life-cycle assessment, cost–benefit analysis, and avoided damage costs [10,22], as well as benefit-transfer methods, which involve the use of existing valuation information from one context to estimate values in another [22,64].

3)

Green finance and Public–Private Partnerships (PPPs)

Several reviews identify mobilizing green finance instruments and PPPs as a potential way to diversify funding sources, reduce reliance on public budgets, and enhance the long-term financial sustainability of SC programs (e.g., [1,55]). According to Chan et al. [63], green finance refers to “local, national, or transnational financial investments from public, private, and alternative sources flowing into environmental and sustainability initiatives.” This may be a viable solution to support the construction, operation, and maintenance of SC development [63].

4)

Ecological compensation as a funding instrument

Ecological compensation policies, such as stormwater management fees, can generate funding for SC interventions. C. Shi et al. [55] (pp. 7-8) note that “by advocating for the ‘polluter-pays’ and ‘beneficiary pays’ principles, ecological compensation aims to restore and substitute ecological functions that have been impaired, thus playing a crucial role in the sustainability discourse” (citing [65,66]). These mechanisms can support public investment and enhance the long-term viability SC initiatives.

4.1.5. The Human Wellbeing Dimension

Of the 50 review articles examined, two were rated highly relevant (scale = 3), four moderately relevant (scale = 2), and 24 briefly addressed the subject of Human Wellbeing (scale = 1). The total relevance score was calculated as (2 x 3) + (4 x 2) + (24 x 1) = 38. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 0.8 on a 0–3 scale, indicating that human wellbeing receives limited attention in the review literature. Analysis of these articles further identified key challenges and opportunities related to human health and wellbeing in the context of SC viability. Figure 13 and Figure 14 summarize these themes and their frequencies of mention.

• Human Wellbeing: Challenges

1)

Insufficient flood risk protection

Intensified flood risk poses a fundamental challenge to SC viability as the protection of human life is the non-negotiable baseline of SC strategies. The literature consistently shows that climate change–driven extreme rainfall, combined with rapid urbanization, has led to flooding events that exceed the capacity of SC systems. Flooding persists as a widespread and escalating hazard, directly threatening human life, property, and public safety (e.g., [35,67]). As Zeng et al. [3] (p. 1) underscore, “The SC program in China is still insufficient to prevent flooding risks effectively. In the past eight years, 24/34 provinces have recorded flooding. Flooding caused a total of 4701 deaths… causing severe health risks to citizens.”

2)

Public health risks and disservices

Literature reveals that SC measures can create two major public-health risks when poorly maintained or overloaded: 1) exposure to polluted stormwater carrying nutrients, pathogens, or heavy metals, and 2) increased mosquito and vector-borne disease risks where stagnant or humid sponge environments support insect breeding. Stormwater overflow events can “deteriorate water quality and jeopardize human health” [23] (p. 3), and heavy metals in runoff may “accumulate in animals and plants and enter the human body through the food chain” [47] (p. 15). At the same time, high-humidity sponge environments can intensify vector exposure, as “mosquito breeding induced by the high humidity… makes it imperative to manage the mosquito problem” [41] (p. 18). These reviews warn that without health-risk-informed design, maintenance, and clogging prevention, SC systems may expose communities to long-term environmental health hazards. These public health-related challenges highlight the need for an integrated approach that puts human wellbeing at the center of resilience and livability

3)

Disturbance and public resistance

Literature reveals that SC measures can generate disruptions that contribute to public resistance. Compared with traditional stormwater drainage systems, many SC interventions are spread over large surface areas. Li and Zhang [51] (p. 9) note that “disturbance to residents’ lives during construction and operation may cause residents to resent” the SC construction (citing [68,69]). Other studies further indicate that certain facilities can encroach on urban living space, intensifying perceived inconvenience and spatial conflicts [62]. In addition, Zhou et al. [37] note that permeable pavements may be prone to weathering, potentially making road surfaces slippery and increasing driving risks.

• Human Wellbeing: Opportunities

1)

Reduce flood risk & improve public health

Sponge City measures can enhance human wellbeing by lowering flood exposure and improving water quality. For example, urban rainwater harvesting “can effectively reduce surface rainfall-runoff peak… and protect the lives and properties of urban residents” [48] (p. 9). Rainwater harvesting facilities, rain gardens, and permeable surfaces can not only help mitigate waterlogging and protect daily life but also decrease exposure to waterborne pollutants and germs [48,70] Stormwater utilization can also strengthen water security and reduce contamination risks, while cooling and evaporation features help alleviate heat-related stress [53]. These integrated benefits may contribute to safer, healthier communities, particularly in densely populated urban areas.

2)

Enhance urban livability and everyday experience

Sponge City features, such as permeable pavements, rain gardens, shading vegetation, and cooling surfaces, can create more comfortable, walkable, and livable environments. These measures have the potential to mitigate heat island effects, regulate temperature and humidity, reduce glare and noise, and improve pedestrian safety, especially in schools, campuses, and community spaces [55,71]. By softening urban hardscapes and improving microclimates, SC designs elevate the daily experience for residents and enhance the desirability and functionality of public spaces.

3)

Provide recreational, cultural, and psychological benefits

Although not a focus in most scholarly work, the review literature does note that nature-based SC landscapes, such as wetlands, green spaces, eco-corridors, and permeable plazas, can provide cultural, recreational, and psychological benefits by supporting mental restoration, educational engagement, and social interaction. These green–blue areas can enhance aesthetics, provide leisure and play spaces, and improve community wellbeing by integrating cultural ecosystem services into urban design [33,45]. Through this human-centered endeavor, SC interventions can help cultivate healthier, more connected communities.

4.1.6. The Civic Engagement Dimension

Of the 50 review articles examined, none was identified as highly relevant (scale = 3), nine as moderately relevant (scale = 2), and 14 as weakly relevant (scale = 1) to the civic engagement dimension. The total relevance score was calculated as (9x2) + (14×1) = 32. Dividing this total by the 50 reviewed articles yields an average weighted relevance score of 0.6 on a 0–3 scale, indicating that Civic Engagement receives the least attention in the review literature. Following an in-depth review, key themes were identified. Figure 15 and Figure 16 present the major civic-engagement-related challenges and opportunities that influence SC viability, along with their frequencies of occurrence across the reviewed articles.

• Civic Engagement: Challenges

1)

Low public awareness

Relevant literature, such as [36,72], reports that the public has limited awareness of SC concepts, functions, and benefits due to insufficient education and public communication [32]. As Chikhi et al. [23] (p. 11) note, “the lack of public understanding and awareness of the Sponge City concept has a negative impact on its success, as evidenced by the lack of support and low public funding for Sponge City.”

2)

Superficial public participation

Public participation is often symbolic, superficial, or limited to post-flood responses rather than embedded early in planning and decision-making. As Yin et al. [57] point out, “the public only cares about sponge city construction when flooding occurs.” Xu et al. [73] (p. 14) further note, SC “has yet to include active stakeholder engagement and is far from supporting stakeholder participation, particularly with respect to local residents.”

3)

Top-down and fragmented governance limits participation

Sponge City’s planning and design processes need cross-sector coordination and joint planning, with stakeholders co-creating knowledge around shared goals [4]. However, “the complex and fragmented structure of China’s administrative system offers less opportunity for participation and collaboration” [38]. This significantly limits stakeholder influence, cross-sector collaboration, and local initiative, constraining adaptive, place-responsive SC implementation.

4)

Lack of solid evidence to gain public trust

As Nguyen et al. [38] (pp. 257-258) report, “China currently has only limited regional data for Sponge City implementation… the lack of evidence becomes a hindrance to empowering … the public to create change and participate in public-private partnerships,” citing [69,56]. This concern is echoed by Xu et al. [10] (p. 12), who note that “in China, lack of the onsite data is the biggest challenge… few cities have monitored operation data.” Without credible, place-specific evidence on performance, SC initiatives struggle to gain public trust.

• Civic Engagement: Opportunities

1)

Early and broad stakeholder engagement

Several review studies highlight the importance of engaging residents, planners, engineers, and local stakeholders early in the process. This can support co-design and community buy-in and potentially enhance the long-term viability of SC projects. As C. Shi et al. [55] (p. 10) emphasize, the development of SC solutions is “inherently a collaborative endeavor… Engaging a broad spectrum of stakeholders early in the planning process is crucial for balancing various interests and ensuring that the proposed interventions are both effective and supported by the community”.

2)

Public awareness-raising and capacity building

Conducting education training courses can help improve public perceptions and engagement [74]. As Chikhi et al. [23] (p. 10) note, “residents may be asked to participate in decision-making processes, provide feedback, and help design these projects.” This capacity building and active participation can “foster a sense of community ownership and pride, while also raising awareness about water conservation, sustainable practices, and environmental stewardship.”

3)

Participatory tools and communication platform

Decision-support tools, participatory planning methods, and digital communication platforms can enhance transparency, knowledge exchange, and informed civic participation, helping bridge technical complexity and public understanding. According to Chan et al. [34] (p. 10), “the well-used social media… helped governmental authorities respond faster and more precisely.”

4)

Local knowledge & ancient wisdom

While not a dominant theme, a small number of SC studies draw on scholarship on ancient and local water-management wisdom. For example, Angelakis and Zheng [75] discuss lessons from historical water-management systems that may inform contemporary approaches. Notably, the review by Cun et al. [76] frames such perspectives as civic engagement resources relevant to SC implementation. “Ancient technologies are not merely historical artifacts, but workable potential models for sustainable water technologies.” Cun et al. [76] (p. 3) also note, “local residents put turtles in the ditches to keep them clean and prevent blockage” (citing [75]), reflecting a locally developed grassroots solution for maintaining drainage performance.

5. Discussion

This section synthesizes the review findings and their implications for SC viability. It begins by examining how the six core dimensions of the proposed framework are represented in the scholarly literature, revealing important imbalances in research attention. It then explores recurring themes and interrelationships across these dimensions, discusses conflicting findings regarding SC performance and impacts, and also compares scholarly priorities with practitioner perspectives.

5.1. Dimensions of SC Viability

This study reveals an imbalance in scholarly attention within the SC viability framework, with a predominant focus on environmental sciences and water resources. Other dimensions, including Governance, Economy, Urban Form, Civic Engagement, and Human Wellbeing, receive much less attention. The keyword co-occurrence analysis clearly reflects this trend, a finding echoed by scholars such as Wang and Palazzo [77] (p. 2), who note that “current assessment of Sponge City outcomes focuses on environmental performance and monitoring and it is often carried on with model evaluation” (citing [78,79]). While this emphasis is understandable given that flooding and stormwater management are primary drivers of China’s SC initiative, it may lead to a skewed understanding of SC viability by disproportionately prioritizing environmental performance metrics, such as flood control and rainwater storage, over other crucial dimensions.

Importantly, SC is inherently multidisciplinary [80]. China’s national policy explicitly frames SC as a multi-purpose strategy, aiming to enhance urban resilience, ecological capacity, and urban livability [81]. Institutional, financial, and social factors are equally important for effective SC planning and implementation. For example, Governance shapes policymaking and management at multiple administrative levels [82]. Economic factors, particularly investment structures and funding mechanisms, are crucial to scaling SC and necessitate greater private-sector involvement [58,63]. Urban Form, the spatial configuration of urban environments [83], impacts the integration of SC interventions within existing and new urban fabrics. Civic Engagement affects public awareness and community acceptance of SC projects [23,32]. Furthermore, the Human Wellbeing dimension reflects how SC solutions can shape public health, urban aesthetics, and overall livability [40]. All are essential for effective SC implementations.

5.2. Interrelated and Repeated Themes across the Six Dimensions

This study reveals that key themes within the six dimensions are highly interconnected and frequently overlap. The Environmental dimension, for example, is closely linked to Urban Form, with similar opportunities and approaches such as blue-green infrastructure and other nature-based solutions. Governance and Economic considerations shape the feasibility and funding mechanisms, such as the PPP of the SC implementations. Similarly, the “one-size-fits-all” problem and the call for place-based, locally adaptive approaches apply across multiple dimensions, such as Environment, Urban Form, and Governance. Moreover, Civic Engagement and Human Wellbeing are closely interrelated. Limited public awareness and participation in SC initiatives can affect implementation effectiveness [3,32]. Conversely, greater stakeholder involvement and community engagement can enhance public acceptance, foster a sense of community ownership and pride, ultimately improving wellbeing outcomes [23,46]. The repeated appearance of these themes suggests that SC development operates as an integrated system rather than a set of isolated components. This interconnectedness highlights the need for more holistic and systematic approaches in both research and practice, moving beyond narrow perspectives to better reflect the complexity of SC implementation and long-term viability.

5.3. Conflicting Findings in SC Review Articles

An examination of the 50 review articles finds noticeable contradictions in terms of the effectiveness and impact of SC implementation. While several studies (e.g., [3,36,84]) highlight SC’s ability to mediate urban flooding through infiltration, retention, and rainwater harvesting, some doubt its efficacy, especially under extreme rainfall circumstances, implying limited performance at the larger scale (e.g., [35,49,67]). Similarly, inconsistent reports emerge about water quality outcomes: some literature suggests that SC systems can filter and cleanse water and minimize runoff contaminants (e.g., [50,57]), while others emphasize hazards like pollutant accumulation, particularly heavy metals in soils, and potential groundwater pollution (e.g., [39,40]). Similar contradictions emerge in public health impacts: while some studies concern increased mosquito breeding in sponge environments [41], others argue that SC measures can reduce the possibility of germs and mosquitoes being deposited in low-lying areas and thus reduce public health risks [3].

Divergent recommendations also extend to potential co-benefits, such as edible plants being incorporated in SC interventions, as some studies promote vegetable planting in rain gardens [54], while others caution against pollutant retention risks in SC facilities [23]. These inconsistencies may reflect differences in local environmental conditions, methodological approaches, and underlying assumptions, as well as potential positionality bias among researchers. Collectively, they highlight the need for more context-sensitive, empirically grounded, and long-term evaluations of SC performance across multiple dimensions.

5.4. Divergence Between Scholarly Focus and Practitioner Priorities

Findings from a recent practitioner-based study by Tang et al. [20] suggest a markedly different prioritization between SC scholarship and practice. Drawing on interviews with 30 practitioners and domain experts, including national- and city-level SC specialists, the study found that governance and economic factors are perceived as the most critical determinants of SC viability [20]. See Figure 17 for comparison.

This disparity highlights a clear difference in emphasis between scholars and practitioners. While academic research primarily focuses on SC’s technical and environmental challenges, practitioners in China view its success as dependent on governance structures, funding mechanisms, and long-term management capacity [20]. This perspective underscores the central role of effective and sustainable governance in SC viability. This is echoed by three well-known Chinese SC experts, She, Xie, and Li [85], noting China’s SC construction “needs to seek institutional breakthrough with the support of national policies.”

6. Conclusion

A trillion-US dollar national program [12], China’s SC initiative is among the most ambitious global efforts to incorporate nature-based solutions into urban stormwater management. Despite its widespread adoption as a planning model across China, its effectiveness and overall sustainability remain contested. To assess the long-term viability of this major public works initiative, a systematic review of 50 review articles was conducted, and the literature was analyzed through a six-dimensional conceptual framework encompassing Environment, Economy, Governance, Civic Engagement, Urban Form, and Human Wellbeing. Findings illustrate that the literature is heavily concentrated on the environmental dimension, while other socioeconomic dimensions receive substantially less attention. This imbalance suggests that current research may capture only a partial picture of SC viability. Moreover, crucial questions pertain to the actual stormwater management capacity of SC interventions in China and the need for a more robust evidence base to assess their effectiveness across diverse urban and climatic contexts.

Given the comprehensive goals of the national initiative, SC viability and associated scholarship depend not only on optimized hydrological and ecological performance but also on effective governance, sustainable financing, integrated spatial planning, and meaningful civic engagement that support long-term environmental, economic, and social outcomes. Existing research is dominated by modeling, conceptual analyses, and short-term assessments. To establish a stronger evidence base, future research should prioritize empirical, practice-oriented investigations. Particular attention should be given to how governance factors, including policymaking, institutional coordination, funding mechanisms, and community participation, influence the long-term functionality and effectiveness of SC implementation. Moreover, the long-term success of urban stormwater management depends largely on operation and maintenance (O&M) [12]; as such, field-based research and long-term monitoring would improve understanding of how SC measures function in practice and throughout their life cycles [10], especially under changing climatic conditions, urbanization pressures, and management regimes.