Green-Gray infrastructure is an innovative approach that combines natural ecosystems with traditional engineering solutions to address environmental and infrastructure challenges. This integrated model enhances resilience against climate impacts while promoting sustainable development. Read here to learn more.
Adapting to the escalating impacts of climate breakdown particularly for coastlines facing sea-level rise and stronger storms requires changing our infrastructure.
The Decent Work in Nature-Based Solutions (NbS) Report was launched at COP 16 of the United Nations Convention to Combat Desertification (UNCCD) and talks about how the adoption of green-gray infrastructure could generate 20–32 million new jobs by 2030.
The report was jointly presented by the International Labour Organization (ILO), the United Nations Environment Programme (UNEP), and the International Union for Conservation of Nature (IUCN).
Green-Gray Infrastructure
- Green Components (Nature-Based Solutions):
- Mangroves, wetlands, and seagrasses: Protect coastlines from storm surges, reduce erosion, and absorb carbon dioxide.
- Forests and vegetation: Provide natural water filtration, stabilize soil, and regulate local climates.
- Coral reefs and oyster beds: Act as natural barriers, dissipating wave energy and protecting shorelines.
- Gray Components (Traditional Engineering Solutions):
- Concrete seawalls and dams: Offer structural support and flood prevention.
- Stormwater systems: Manage urban water runoff and prevent flooding.
- Levees and dikes: Protect inland areas from rising water levels.
- Integration:
- Green and gray elements are strategically combined to amplify their collective strengths. For example, mangroves (green) can be planted alongside seawalls (gray) to enhance coastal protection while fostering biodiversity.
By the numbers
$94 Trillion
An estimated US$ 94 trillion will be spent on infrastructure globally in the next 20 years.
70% of emissions
Roughly 70% of global greenhouse gas emissions come from carbon-intensive gray infrastructure such as power plants, buildings and transportation.
2x by 2030
By 2030, the number of people impacted by floods will double worldwide, urban property damaged by riverine floods will increase threefold, and property damaged by coastal storm surges and sea level rise will increase tenfold.
Green Infrastructure vs. Gray Infrastructure
Green Infrastructure |
Gray Infrastructure |
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Definition |
Natural systems and features that deliver environmental, social, and economic benefits, while promoting ecosystem health. |
Man-made engineered systems are designed to manage specific challenges such as water supply, transportation, and urban development. |
Examples |
Forests, floodplains, wetlands, grasslands, mangroves, urban parks, and soils. |
Dams, seawalls, roads, bridges, pipes, levees, and water treatment plants. |
Key Benefits
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Applications
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Benefits of Green-Gray Infrastructure
- Climate Resilience: Combats rising sea levels, storm surges, and floods by combining the flexibility of ecosystems with the reliability of engineered solutions.
- Environmental Sustainability:
- Enhances biodiversity by conserving and restoring natural habitats.
- Promotes carbon sequestration through vegetation like mangroves and seagrasses.
- Economic Efficiency:
- Cost-effective: Natural systems can reduce the need for expensive repairs or upgrades to gray infrastructure.
- Provides ecosystem services such as fisheries, tourism, and clean water.
- Social Impact:
- Protects vulnerable communities by reducing disaster risks.
- Supports livelihoods dependent on healthy ecosystems.
Examples of Green-Gray Infrastructure
Beira in Mozambique, named one of the world’s cities most threatened by climate change, is showing how other cities in the country and across Africa can combine innovative green approaches and conventional gray infrastructure to protect residents and assets from climate hazards while enhancing ecosystems and services.
Coastal and Flood Management
- Living Breakwaters Project, USA:
- Location: Staten Island, New York
- Combines constructed oyster reefs with concrete breakwaters to protect against storm surges while restoring marine ecosystems.
- Benefits: Reduces wave energy, fosters biodiversity, and improves water quality.
- Room for the River Program, Netherlands:
- Uses widened riverbanks, floodplains, and engineered dikes to manage flood risk.
- Balances gray structures with restored natural river ecosystems.
- Mangrove Rehabilitation, Philippines:
- Combines mangrove reforestation with seawalls to reduce storm surge impacts.
- Restores critical habitats while protecting vulnerable coastal communities.
Urban Stormwater Management
- Sponge Cities, China:
- Locations: Pilot cities such as Wuhan, Chongqing, and Shenzhen.
- Features include permeable pavements, green roofs, artificial wetlands, and underground reservoirs to manage urban flooding.
- Aims to capture and reuse 70% of rainwater.
- Portland Green Streets Program, USA:
- Location: Portland, Oregon
- Uses bioswales, rain gardens, and natural water retention systems to manage stormwater runoff.
- Reduces pressure on sewer systems while greening urban spaces.
Ecosystem Restoration and Infrastructure
- Coral Reef Revitalization in Seychelles:
- Restored coral reefs combined with submerged artificial structures to protect against coastal erosion.
- Enhances fish stocks and protects tourism-dependent economies.
- Bamboo Barriers, Bangladesh:
- Location: Coastal regions of Bangladesh
- Uses bamboo fences alongside engineered dikes to reduce tidal wave impacts and prevent erosion.
- Encourages sediment deposition and mangrove growth.
Water Supply and Quality
- Guangzhou Greenways, China:
- Location: Guangdong Province, China
- Integrates wetlands with water treatment plants to purify water and recharge aquifers.
- Connects urban areas with green corridors, promoting recreation and ecosystem services.
- Green Roofs in Berlin, Germany:
- Green roofs are installed across buildings to reduce stormwater runoff and improve water quality.
- Helps regulate urban temperatures while managing rainwater sustainably.
Climate Adaptation and Heat Mitigation
- Urban Forest Program, Melbourne, Australia:
- Urban forests combined with stormwater systems to mitigate heat islands and improve water retention.
- Enhances biodiversity and air quality in urban environments.
- Chennai Wetland Restoration, India:
- Restores degraded wetlands as natural water retention basins alongside conventional drainage systems.
- Reduces urban flooding and enhances local biodiversity.
Agricultural Landscapes
- Tidal Marsh Restoration, San Francisco Bay, USA:
- Restores tidal marshes alongside levees to buffer agricultural lands from flooding.
- Improves carbon sequestration and provides wildlife habitats.
- Contour Farming and Terraces, Kenya:
- Combines gray terracing with natural vegetation to prevent soil erosion and improve water retention in agricultural regions.
Challenges and Considerations
- Initial Costs: High upfront investments may deter adoption despite long-term benefits.
- Maintenance and Monitoring: Requires ongoing efforts to manage both natural and engineered components effectively.
- Policy and Collaboration: Calls for interdisciplinary approaches and cooperation among governments, engineers, environmentalists, and local communities.
Blue Infrastructure
Blue infrastructure refers to natural or man-made water-related systems designed to manage, conserve, and utilize water resources effectively.
It focuses on the sustainable management of water bodies, such as rivers, lakes, wetlands, and oceans, while integrating them into urban and rural development to enhance ecosystem services and resilience.
- Natural Water Systems: Rivers, streams, lakes, ponds, wetlands, estuaries, and oceans.
- Engineered Solutions: Man-made canals, reservoirs, dams, rainwater harvesting systems, and drainage systems.
- Urban Integration: Green roofs with water capture, permeable pavements, bioswales, and stormwater retention ponds.
- Coastal and Marine Systems: Mangroves, coral reefs, sea grasses, and sustainable aquaculture systems.
Benefits of Blue Infrastructure
- Climate Resilience:
- Helps mitigate urban flooding by managing stormwater.
- Supports adaptation to rising sea levels and extreme weather events.
- Water Quality Improvement: Reduces water pollution through natural filtration in wetlands and vegetation buffers.
- Biodiversity Conservation: Provides habitats for aquatic and terrestrial species.
- Economic Benefits:
- Enhances fisheries, tourism, and recreation industries.
- Reduces costs associated with gray infrastructure (e.g., traditional drainage systems).
- Urban Livability: Creates aesthetically pleasing and multifunctional spaces, improving mental and physical well-being.
Examples of Blue Infrastructure Projects
- Urban Wetlands: Restored wetlands in cities like New York’s Jamaica Bay improve flood management and biodiversity.
- Rainwater Harvesting: Singapore’s Active, Beautiful, Clean Waters program integrates blue infrastructure into urban design to collect rainwater and enhance public spaces.
- Coastal Defense: Mangrove restoration in Vietnam to combat coastal erosion and provide storm protection.
- Green-Blue Corridors: London’s Lea River Park connects urban areas while managing stormwater and improving biodiversity.
Role in Sustainable Development
Blue infrastructure aligns with Sustainable Development Goals (SDGs):
- SDG 6: Clean Water and Sanitation.
- SDG 11: Sustainable Cities and Communities.
- SDG 13: Climate Action.
- SDG 14: Life Below Water.
By promoting water-sensitive urban design and integrating ecosystems into planning, blue infrastructure serves as a cornerstone for building resilient, sustainable communities.
Conclusion
By blending the best of nature and engineering, green-gray infrastructure represents a forward-thinking approach to building resilient, sustainable, and adaptive communities in the face of global environmental challenges.
Frequently Asked Questions (FAQs)
Q. What is an example of gray infrastructure?
Ans: Gray infrastructure is traditional stormwater infrastructure in the built environment such as gutters, drains, pipes, and retention basins.
Q. What is an example of green infrastructure?
Ans: On the local level, green infrastructure practices include rain gardens, permeable pavements, green roofs, infiltration planters, trees, and tree boxes, and rainwater harvesting systems.
Q. What is natural infrastructure?
Ans: Natural infrastructure, also referred to as green infrastructure, uses existing natural areas (and engineered solutions that mimic natural processes) to minimize flooding, erosion, and runoff. Additional benefits can include increased recreational opportunities and wildlife habitat, as well as cleaner water.
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-Article by Swathi Satish
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