Blue-Green Infrastructure for Climate Resilience and Urban Multifunctionality in Chinese Cities

Overview

  • Article: Blue-Green Infrastructure for climate resilience and urban multifunctionality in Chinese cities.
  • Authors: Stephanie A. Siehr, Minmin Sun, José Luis Aranda Nucamendi; Journal: WIREs Energy and Environment, 2022.
  • Core idea: Blue-Green Infrastructure (BGI) combines hydrological (blue) and vegetated (green) elements to bolster climate resilience and urban multifunctionality in high-density Chinese cities.
  • Context: BGI is deployed in new developments, retrofits, and revival of ancient water infrastructure; major focus on Sponge City Initiative designed to address pluvial flooding.
  • Evidence base: Literature shows progress in stormwater management and some rainwater reuse; social, ecological, and energy-related co-benefits documented; but significant design, governance, and data gaps remain.
  • Key goals: Integrate ecological and social functions to deliver carbon-neutral, climate-resilient infrastructure, improved air/water quality, ecosystem regeneration, and enhanced urban quality of life.
  • Core frameworks referenced: ICLEI-EU, UNESCO-IHE, IWA climate adaptation framework; Arup City Resilience Index; Meerow & Newell multicriteria GI planning.
  • Definitions introduced: BGI is a type of nature-based solution that blends hydrological and vegetative elements; related terms include GI, green stormwater infrastructure, LID, water-sensitive urban design, sustainable drainage systems, and NBS.
  • Box 1 (types and functions): outlines BGI types and their functions; graphics show integration of BGI in urban design (Figure 1).
  • Location context: Chinese Sponge Cities Initiative (launched 2013) to address severe pluvial flooding; concept rooted in ecological civilization and traditional hydrological practices.
  • Main takeaways: BGI offers eight resilience qualities and multiple functions, but reaching robust, inclusive, and truly transformative outcomes requires integrated planning, data, governance reform, and public engagement.

Introduction

  • Central problem: Rapid urbanization in China increases impervious surfaces, disrupts water cycles, and threatens water supply, flood risk, and ecological health; climate disruption exacerbates these issues.
  • Urbanization pace: Urbanized land has grown at a 12% average annual rate since 1990, outpacing population growth; leads to pollutant runoff and loss of lakes/wetlands.
  • Water-related hazards linked to urbanization and climate change:
    • Flooding (pluvial and fluvial) and coastal erosion; increased runoff and pollution from peri-urban industry/agriculture.
    • Water scarcity due to pollution and reduced precipitation in parts of China; drought risk, especially in arid north.
    • Sea-level rise and coastal hazards in deltas/floodplains.
  • Public health and social implications: Impervious surfaces reduce urban ecology, fragment communities, degrade air/water quality, and increase heat island effects, contributing to health issues (respiratory, cardiovascular, heat-related illnesses).
  • Research questions and approach:
    1) What climate/urbanization hazards affect Chinese urban infrastructure? Context via water cycle impacts using ICLEI-EU/UNESCO-IHE/IWA framework.
    2) How can BGI provide climate resilience and urban multifunctionality? Use resilience concepts (Arup City Resilience Index) and multicriteria GI planning model (Meerow & Newell).
    3) What BGI types are used in Chinese cities, and what is progress/potential?
  • Box 1: Blue-Green infrastructure—types and functions (highlights that any BGI type can deliver multiple functions and that BGI works best as an integrated network with gray infrastructure).
  • Illustrative BGI components (Figure 1): Rain gardens, parks-as-detention basins, bioswales, green roofs, green walls, rainwater harvesting, wetlands, etc.
  • Sponge City context: BGI is central to China’s Sponge City Initiative (2013) to address pluvial flooding; rooted in ancient hydrological practices and ecological modernization.
  • Terminology note: In this literature, terms like ecological civilization, new urbanization, and sponge city are used frequently; resilience and multifunctionality are increasingly linked to BGI analysis.
  • Framing of resilience and multifunctionality: BGI is viewed as a living infrastructure with potential to transform vulnerability and enhance social equity.

BGI for climate resilience and urban multifunctionality

Box 1: Blue-green infrastructure—types and functions

  • Types of BGI and their functions (examples and notes):
    • Urban forests and trees: Individual trees are beneficial; forests provide multiple functions.
    • Parks and ponds: Vegetated parks; detention basins (dry ponds) and wet ponds for water retention; flood prevention and public health benefits.
    • Rain gardens: Small vegetated areas enabling detention, filtration, infiltration, habitat, and enjoyment.
    • Green roofs, facades, balconies: Vegetated surfaces providing stormwater detention, cooling, air quality benefits, and public health advantages.
    • Bioswales and stormwater boulevards: Vegetated channels along paved surfaces to detain, filter, and convey water; protect water quality and infrastructure.
    • Wetlands and riparian zones: Constructed or restored; protect urban services and biodiversity.
  • Water flow functions: Detention, conveyance, evaporation, rainwater harvesting, groundwater recharge (infiltration).
  • Water quality functions: Pollutant removal via filtration/sedimentation.
  • Ecological functions: Biodiversity support, habitat, soil fertility, pollination, erosion control, nutrient cycling.
  • Temperature control: Cooling via shading, higher albedo, evapotranspiration; reduces urban heat island effects.
  • Air quality: Pollutant removal and smog reduction.
  • Carbon sequestration: Bio-based carbon uptake by vegetation.
  • Economic enhancement: Attract investment, tourism; increases property values; protects infrastructure.
  • Public health and social cohesion: Noise reduction, recreation, stress reduction, access to nature, education, cultural activity.

Box 1 takeaway on resilience and multifunctionality

  • BGI functions best when integrated across watershed scale with both green and gray infrastructure.
  • In a dense city, BGI supports multiple services simultaneously—stormwater management, water supply augmentation, cooling, habitat, and quality of life.

City resilience definition and the eight resilience qualities (Table 2)

  • City resilience definition used: Arup (2017) — The capacity of cities to function so that people can survive and thrive regardless of stresses or shocks; emphasizes well-being and equity for the most vulnerable.
  • Expanded view for BGI: Includes nonhuman actors (flora, fauna) in urban resilience and eco-civilization framing.
  • Eight resilience qualities of BGI for Chinese cities (Table 2):
    • Flexible
    • Inclusive
    • Integrated
    • Multifunctional
    • Reflective
    • Regenerative
    • Resourceful
    • Robust
  • How these qualities map to indicators: Reduction in runoff, pollutant loads, and nutrient loads; geospatial co-benefits; and social indicators.
  • Quantitative and qualitative indicators used: Stormwater performance metrics, geospatial co-benefits, and social indicators (e.g., accessibility, equity).
  • Conceptual note: Resilience is not just risk reduction; it includes transforming systems for greater adaptability and social justice.

How BGI provides multifunctionality in high-density cities

  • Core idea: In dense urban contexts, BGI should deliver multiple benefits from the same footprint (multifunctionality).
  • How multifunctionality works: Shade trees along transit routes; permeable pavement; bioswales connected to parks; retention basins; cooling, pollutant removal, and climate adaptation functions in one network.
  • Economic and operational considerations: BGI is often less expensive than large gray infrastructure; integrated planning across city services yields higher resilience.
  • Integrated planning concept: Watershed-scale planning connecting BGI with gray infrastructure to meet hydrological, ecological, and social needs over long time horizons; requires cross-agency coordination (water, energy, transport, environment, social/economic sectors).
  • Governance note: Chinese governance is highly vertical (tiao-tiao kuai-kuai); horizontal integration across agencies remains a challenge for BGI integration.
  • Data and evaluation: Need for better data and models to quantify multifunctionality and inform planning.

Progress on BGI in Chinese Cities

Context and historical development

  • Early origins: Garden City and Eco-Garden City programs (1990s); ecological urbanism work (Peking University) (1990s); Eco-City programs (2000s); Low-Carbon City programs (2007–2008); eco-civilization concept (2007).
  • Policy milestones: National Climate Adaptation Plan; Sponge City Initiative (2013); New Urbanization Plan (2014).
  • Targets: The Sponge City Initiative aimed for absorption/usage of at least $70\%$ of rainwater in $80\%$ of urban areas by 2030 (central policy objective).
  • Pilot phase: 2015–2016, 30 Sponge City pilots selected by MOHURD to address flood risk and water scarcity; pilots combine rain gardens, bioswales, bioretention ponds, green roofs/walls, permeable pavement, tree planting, and rainwater harvesting (cisterns/groundwater).
  • Reported progress: Increased infiltration and reduced runoff; flood prevention; reduction in stormwater pollutants; some progress in rainwater harvesting for nonpotable uses (irrigation, sanitation, industrial use).
  • Limitations: Heterogeneous data across Sponge Cities; quantification across cities remains challenging; extreme weather events test robustness of both gray and BGI systems designed for historical climate ranges (1-in-30-year event vs 1-in-1000-year).

Representative city examples (Table 3) – BGI types, functions, and resilience qualities

  • Olympic Park, Beijing (Beijing region): Sponge City design with sunken green spaces/underground detention; permeable pavement; water storage cisterns; overflow to separate sewer; new development; functions include flood prevention, groundwater recharge, stormwater utilization, ecosystem regeneration; resilience qualities: Multifunctional, Resourceful.
  • Tianjin University, Tianjin: 3-zone design (new development) with green roofs and bioretention lake; inner ring bioswales/wetland, outer ring eco-corridors; connected to canals/rivers; flood prevention, reduced runoff, stormwater purification, recreation and social gathering, ecosystem regeneration; resilience qualities: Flexible, Integrated, Multifunctional, Regenerative.
  • Xi’an and Xixian New Area, Shaanxi: Rain gardens, roadside bioswales, grassland, constructed lake, permeable pavement (retrofit + new development); rainwater harvesting; flood prevention; stormwater purification; resilience qualities: Resourceful, Multifunctional.
  • Ganzhou, Jiangxi: Ancient water doors within city walls; network of constructed ponds and parks; Fushou ditch system with underground drainage tunnels; fluvial/pluvial flood prevention; stormwater drainage and storage; public amenities; resilience qualities: Reflective, Resourceful.
  • Hangzhou, Zhejiang: Eco-City with extensive tree canopy, green roofs, rain gardens, and wetland restoration; cooling, flood prevention, air/water pollutant reduction; reduced wind speeds; resilience qualities: Resourceful, Multifunctional.
  • Ningbo, Zhejiang: Eco-corridor of woodlands and wetlands (retrofit + revival of ancient BGI); flood prevention; stormwater purification; water storage; ecosystem regeneration; public health and recreation; resilience qualities: Reflective, Regenerative.
  • Zhengzhou, Henan: Sponge City retrofit with green corridors, bioswales, rain gardens, permeable pavement, constructed wetlands, artificial lake, connected to drainage tunnels; flood prevention; rainwater harvesting; cooling of UHI; resilience qualities: Resourceful, Integrated.
  • Huangshi, Hubei: Green corridors, urban trees, parks and rain gardens, permeable pavement, lake/wetland restoration, water storage (retrofit); flood prevention; water/soil pollution reduction; rainwater harvesting; ecological regeneration; resilience qualities: Reflective, Regenerative.
  • Regional/climate note: China’s seven regions; Koppen climate zones represented (e.g., Cfa, Cwa, Bsk).

Concrete examples and outcomes

  • Tianjin Peiyang Campus (Northern coastal region): Sponge City design integrated into new campus; features green roofs, permeable pavement, bioswales, a central bioretention lake, inner ring wetlands, outer buffer eco-corridors; opened 2015; performed well during the 2016 Tianjin storm with no campus flooding; demonstrates regenerative design that protects campus ecosystems.
  • Hangzhou (East Zhejiang): Early adoption (since 2005) leading to >60% tree canopy by 2019; restored wetlands (e.g., Xixi National Park) with significant biodiversity gains (bird species from 79 to 181); improvements in air and water quality; urban cooling effects documented (temperature reductions 4–6°C in some areas).
  • Ningbo (East Zhejiang): Ancient water infrastructure revived as eco-corridors; local guidelines (2014) to address five water issues and leverage Sponge City; focus on woodlands, wetlands as flood buffers; adaptation to dense urban form with native species for nutrient removal; indicates a balance between revival and modernization.
  • Zhengzhou (South Central): Sponge City investments (~US$8 billion) including green corridors, bioswales, green roofs, permeable pavement, wetlands, and tunnels; 2021 cloudburst delivered 778 mm in 1 day; 293 deaths; 500+ trapped; 1 million displaced; ~US$18B in damages; event exceeded 1-in-30-year design, hitting 1-in-1000-year extremes; underscores need for more robust design and social adaptive capacity.

Lessons for success

  • National attention and funding accelerate local action.
  • Greater multifunctionality achievable in new construction and university partnerships; retrofits are important but more challenging.
  • Revival/updates of ancient water infrastructure yield Chinese-specific BGI approaches (e.g., flood strategies, canal networks).

Governance, financing, and maintenance insights

  • Financing: Central government funded much of Sponge City initial investments; current financing model envisions 10% public sector, 50% private sector via PPP, 40% local government; ongoing operation and maintenance, monitoring, and adaptation require sustained funding.
  • Public engagement: Public education and community engagement are essential for broader acceptance and long-term success.
  • Data gaps: Monitoring data insufficient for robust cross-city comparisons; need standardized metrics and longer-term performance tracking.

Challenges and Potential for BGI in Chinese Cities

Challenges

  • BGI for very large, high-density cities: Urban form with >1 million residents; need vertical infrastructure (green walls/roofs, underground storage) to achieve infiltration; plan for habitat regeneration and ecosystem support in compact spaces.
  • Extreme weather and climate change: Current designs focused on 1-in-30-year events; increasingly frequent extremes require robustness to 1-in-1000-year events; need flexible and adaptive design.
  • Top-down governance and fragmented engineering practices: Limited ecologist/sociologist involvement; governance tends to be vertical (tiao-tiao kuai-kuai) with weak horizontal coordination across agencies; integration of land and water management remains a challenge.
  • Financing, monitoring, operation, and maintenance: Centralized funding has shifted to PPP and local contributions; long-term maintenance and performance monitoring require more robust data collection and governance.
  • Data limitation: Insufficient baseline and post-implementation data to quantify performance and to calibrate models; need standardized indicators for multi-functionality and resilience.
  • Public engagement and social equity: Public education and inclusive processes are not consistently integrated into MOHURD guidelines; inclusive design and ecosystem health require active community involvement.

Potential for BGI

  • Expand climate/hazard coverage beyond pluvial flooding: Use BGI to address extreme heat, sea-level rise, habitat fragmentation, energy demand, and air/water quality more comprehensively.
  • Multifunctionality and integration: Design BGI to function across multiple city services (water, energy, transport, health); align with watershed planning to optimize resource use and reduce reliance on gray infrastructure.
  • Inclusive and regenerative approaches: Target disadvantaged neighborhoods for enhanced cooling, habitat restoration, and access to nature; support ecological regeneration and community benefits.
  • Technological and policy innovations: Green roofs and biosolar roofs, coastal wetland protection, delta habitat maintenance, and interconnected eco-corridors can enhance resilience across hazards.
  • Data-driven planning: Develop standardized metrics for hydrology, ecology, social benefits, and resilience outcomes to guide investment and policy.

Conclusion

1) Hazards and impacts: The review summarises climate and urbanization hazards affecting Chinese cities (Table 1). Pluvial flooding and water scarcity are prominent concerns; extreme heat and sea-level rise require more attention, especially under future climate scenarios like 1.5°C and beyond. Climate change risks are already evident, and future risks are likely to intensify, underscoring the need for forward-looking designs.

  • Key quantitative notes: 81% of major Chinese cities exhibit urban heat island effects; 0.25°C per decade warming since 1965; 1.5–2.0°C warming scenarios imply greater drought and water stress in northern regions; heavy rainfall events can cause significant damages (e.g., Zhengzhou 2021). By 2030, Sponge City aims to absorb ~70% of rainwater in ~80% of urban areas.

2) BGI as climate resilience and multifunctionality: BGI provides eight resilience qualities and supports urban multifunctionality in high-density cities. It helps mitigate heat, improve air/water quality, provide water management, and create social and ecological co-benefits. Revival of ancient water infra combined with contemporary BGI technologies shows promise for culturally appropriate, locally adapted solutions. However, robust, inclusive, and robust (Robust) resilience remains under-realized relative to Flexible, Inclusive, Integrated, Multifunctional, Reflective, and Regenerative capacities.

3) Progress and potential in large Chinese cities: There is growing adoption of BGI and Sponge City initiatives, with some measurable benefits in infiltration, runoff reduction, rainwater harvesting, and cooling. Yet, data gaps and vulnerability to extreme events indicate the need for more robust design and monitoring. Integrated, cross-sector planning and public engagement are essential to broaden BGI’s benefits and to address a wider range of hazards (heat, sea-level rise, habitat fragmentation).

Final takeaway

  • To maximize resilience and multifunctionality, Chinese cities should pursue: (a) more robust BGI designs capable of withstanding extreme events; (b) cross-sector, integrated planning across water, energy, transport, environment, and social sectors; (c) inclusive governance and community engagement to ensure equitable distribution of benefits; (d) ongoing data collection and evaluation to quantify co-benefits and guide adaptive management.

References and notes

  • The article compiles evidence from multiple sources (e.g., Loftus et al., 2011; Jiang et al., 2018; Nguyen et al., 2019; Chan et al., 2022; Tang et al., 2018) and uses Box 1 for typologies, Table 1 for climate/urbanization hazards, Table 2 for resilience qualities, and Table 3 for city examples.
  • Key numerical details include:
    • Sponge City target: 70%70\% of rainwater absorbed in 80%80\% of urban areas by 2030.
    • UHI prevalence: 81%81\% of major cities affected.
    • Temperature trends: 0.25∘C0.25^\circ\mathrm{C} per decade since 1965; future extreme heat projections in South China showing up to a threefold increase in extreme heat events (South China region).
    • Economic damages from Zhengzhou 2021: nearly US$18 billionUS\$18\text{ billion} in damages; 293 deaths.
    • Rainfall event severity: 1-in-1000-year event; planning for 1-in-1000-year extremes remains inadequate in some cases.
  • Equations and formulas used in notes are presented in LaTeX format where appropriate, e.g. the climate hazard-risk framing: extVulnerability=f(extExposure,extSensitivity,extAdaptiveCapacity)ext{Vulnerability} = f( ext{Exposure}, ext{Sensitivity}, ext{Adaptive Capacity}) (IPCC definition).
  • For further study, consult the cited references in the article (Jiang et al., 2018; Tang et al., 2018; Chan et al., 2022; Nguyen et al., 2019; Ramboll, 2016; Arup, 2017).