3.1.2 sustainable cities

waste and slum management, urban reimaging

Why is effective waste management important for sustainable urban development?

• Environmental: Prevents land, air and water pollution, including leachate contamination and methane (CH₄) emissions.

• Social: Reduces disease transmission, improves quality of life and protects vulnerable communities.

• Economic: Reduces healthcare costs, protects tourism/property values and recovers valuable resources.

What causes increasing waste generation in developed cities?

• Population growth and urbanisation → more waste generated.

• Rising affluence → greater consumption and disposal.

• Single-use culture → more packaging waste.

• Globalisation and e-commerce → increased packaging.

• Planned obsolescence → frequent replacement of electronics → e-waste.

• Food waste → excessive consumption and strict food standards.

Why is waste management difficult in developing countries (LDCs)?

• Insufficient government funding → inadequate waste collection.

• Rapid urbanisation → waste generation exceeds collection capacity.

• Poor infrastructure → inaccessible informal settlements.

• Weak governance → illegal dumping and open burning.

Consequences: Waste accumulation → pollution, disease transmission and environmental degradation.

How does the Payatas Dumpsite, Philippines, illustrate problems of waste mismanagement?

• 2000: Garbage landslide killed over 200 people.

• Open dumping → soil and water pollution.

• Informal waste pickers depended on the dumpsite for income despite hazardous conditions.

• Poor communities disproportionately exposed to environmental and health risks.

Evaluation: Demonstrates environmental injustice and the trade-off between livelihoods and environmental protection.

What are the advantages and disadvantages of landfills?

Advantages:

• Relatively cheap and simple.

• Can accommodate large waste volumes.

Disadvantages:

• Leachate → groundwater contamination.

• Organic decomposition → methane emissions.

• Large land requirements.

• Waste takes decades/centuries to decompose.

How does informal recycling contribute to sustainability? Use the Zabbaleen, Cairo.

• Informal collectors collect, sort and sell recyclable materials.

• Zabbaleen recycle approximately 80% of collected waste, compared with 20–25% for many Western collection companies (notes).

• Environmental: Reduces landfill waste and conserves resources.

• Economic: Creates jobs and income.

Limitation: Poor working conditions and vulnerability to government policies.

How does Curitiba's Green Exchange Programme promote sustainable waste management?

Residents exchange recyclable materials for surplus food.

• Environmental: Encourages recycling and reduces waste.

• Social: Improves food security for low-income residents.

• Economic: Supports local farmers.

Evaluation: Integrates environmental, social and economic sustainability.

How does Waste-to-Energy (WTE) incineration work, and what are its trade-offs?

Waste burned at high temperatures → heat → steam → turbines → electricity.

Advantages:

• Reduces waste mass by 80–85%.

• Reduces waste volume by 95–96%.

• Generates electricity and reduces landfill demand.

Disadvantages:

• Toxic emissions/heavy metals.

• High construction and operating costs.

• Residual ash requires disposal.

• May discourage recycling.

How does Singapore manage solid waste sustainably?

• Incineration reduces waste volume and generates electricity.

• Recycling recovers valuable materials.

• Semakau Landfill receives incineration ash and non-incinerable waste.

Statistics from notes:

• 38% incinerated for electricity.

• 60% recycled.

• 2% sent directly to landfill.

Evaluation: Effective for land-scarce cities, but waste reduction remains necessary.

How does Copenhagen use economic incentives to promote recycling?

• Waste taxation → encourages households and industries to reduce waste.

• Bottle deposit-return system → residents receive refunds for returned containers.

• Recycling increased from 26% to 61% between 1987 and 1996 (notes).

Evaluation: Financial incentives encourage behavioural change and resource recovery.

What is the waste management hierarchy?

Most to least preferred:

1. Prevention

2. Reuse

3. Recycling

4. Energy recovery

5. Incineration

6. Landfilling

Principle: Preventing waste is more sustainable than disposing of waste after generation.

What is the difference between linear and circular urban metabolism?

Linear: Take → Make → Use → Dispose

• High resource consumption.

• High waste generation.

Circular: Reduce → Reuse → Recycle → Recover

• Resources remain in use longer.

• Reduces waste and resource depletion.

• Promotes long-term sustainability.

What are slums and their main characteristics?

Slums are urban areas characterised by substandard housing, overcrowding, poverty and deprivation.

Characteristics:

• Inadequate clean water and sanitation.

• Poor housing quality.

• Overcrowding.

• Insecure land tenure.

• Limited basic services.

Why do slums develop in developing countries (LDCs)?

Rapid rural–urban migration:

• Push: Agricultural mechanisation, rural poverty and unemployment.

• Pull: Better jobs, wages, healthcare and education.

Migration → population growth exceeds affordable housing supply → informal settlements.

Other causes:

• Poor governance and urban planning.

• Insufficient funding for housing.

• Informal employment → low incomes.

• Political instability and natural disasters → displacement.

Why do slums develop in developed countries (DCs)?

• Economic inequality → poorer groups cannot afford formal housing.

• Lack of affordable housing → substandard housing and overcrowding.

• Poor urban planning → inadequate infrastructure.

• Social exclusion/discrimination → concentration of marginalised communities.

What are the environmental, social and economic impacts of slums?

Environmental:

• Poor sanitation → water contamination.

• Poorly built housing → fire/flood vulnerability.

Social:

• Overcrowding → disease transmission.

• Inadequate healthcare and sanitation → poor health.

• Insecure tenure → eviction risks.

Economic:

• Informal jobs → unstable incomes.

• Poor education and health → reduced productivity.

What is slum clearance, and what are its advantages and disadvantages?

Slum clearance = demolition of informal settlements, often followed by redevelopment or relocation.

Advantages:

• Removes unsafe housing.

• Enables infrastructure development.

• Improves living conditions if rehousing is adequate.

Disadvantages:

• Disrupts livelihoods and communities.

• Relocation increases commuting costs.

• May cause displacement and social exclusion.

Why was Singapore's slum clearance and public housing programme successful?

• Housing and Development Board (HDB) established in 1960.

• Large-scale public housing replaced slums and squatter settlements.

• Central Provident Fund (CPF) supported homeownership.

• Housing integrated with transport, schools and amenities.

Success factors:

• Strong government support.

• Long-term planning.

• Adequate funding.

• Affordable housing provision.

Why was the Cingapura Project in São Paulo, Brazil, relatively unsuccessful?

• Began in 1992 to relocate favela residents into apartment buildings.

• Only 14,000 units built against 100,000 proposed.

• Residents struggled to afford rent.

• Small apartments and relocation disrupted lifestyles.

Evaluation: Slum relocation may fail when affordability and residents' needs are neglected.

What is slum upgrading, and why is it often preferred to clearance?

Slum upgrading = improving existing settlements without necessarily relocating residents.

Measures:

• Improve water, sanitation and drainage.

• Upgrade roads, electricity and housing.

• Provide healthcare and education.

• Strengthen land tenure security.

Advantages:

• Preserves communities and livelihoods.

• Reduces displacement.

• Improves quality of life.

Limitations:

• High costs.

• Difficult coordination.

• May not solve overcrowding.

How does land tenure security improve slum conditions? Use Rio de Janeiro, Brazil.

• Residents given opportunities to formally register ownership of their homes.

• Qualifying residents could claim ownership after five years of occupation under Brazilian law.

Benefits:

• Reduces eviction risks.

• Encourages investment in home improvements.

• Increases residential stability.

Limitation: Rising land values may increase pressure on poorer residents.

How does community participation improve slum conditions? Use Rocinha and Kibera.

Rocinha, Brazil:

• Self-help housing → residents improve homes using their own labour and resources.

• Improvements include stronger structures, electricity and sanitation.

Kibera, Kenya:

• Wheelbarrow ambulance transports patients through narrow streets.

• Improves emergency healthcare accessibility.

Evaluation: Bottom-up approaches address local needs but require financial and institutional support.

Why do slum improvement strategies fail?

• Lack of community involvement → local needs ignored.

• Insufficient funding → incomplete infrastructure.

• Forced evictions → displacement and livelihood loss.

• Weak governance/corruption → poor implementation.

• Environmental hazards → continued flood/landslide risks.

• Persistent poverty → residents cannot afford improvements.

Evaluation: Long-term success requires good governance, affordable housing, secure tenure and community participation.

What is urban reimaging and why is it necessary?

Urban reimaging = strategies to change an urban area's image and identity to attract residents, tourists, businesses and investors.

Economic reasons:

• Population loss → reduced tax revenue.

• Business closures → unemployment.

• Abandoned infrastructure → declining property values.

Social reasons:

• Crime and deprivation.

• Negative perceptions and stigma.

Aim: Reverse urban decline and promote regeneration.

How is the success of urban reimaging evaluated?

Economic:

• Investment and business growth.

• Employment and tourism.

• Property values and occupancy rates.

Social:

• Population growth and social inclusion.

• Community participation.

• Heritage preservation and improved amenities.

Environmental:

• Green initiatives.

• Reduced pollution.

• Increased biodiversity.

Evaluation: Economic growth does not necessarily mean socially equitable development.

What are city branding and place branding? Give examples.

City branding: Creating a distinctive city identity to attract investment, tourism and residents.

Place branding: Promoting a place's unique cultural, historical or environmental identity.

Examples:

• Amsterdam — I amsterdam: Inclusive, vibrant city image.

• Dubai — Be My Guest: Luxury and hospitality.

• Malaysia — Truly Asia: Cultural diversity and natural attractions.

How did Bilbao's Guggenheim Museum promote urban reimaging?

• Bilbao suffered industrial decline and unemployment.

• Guggenheim Museum opened in 1997.

• Iconic architecture transformed Bilbao into a cultural tourism destination.

Success:

• Increased tourism.

• Attracted investment.

• Improved international image.

• Stimulated surrounding regeneration.

Limitations:

• High costs.

• Unequal distribution of benefits.

• Potential gentrification.

How did London Docklands redevelopment promote regeneration, and what were its limitations?

• London Docklands Development Corporation established in 1981.

• Former industrial docklands converted into commercial, residential and financial districts.

• Docklands Light Railway (DLR) improved accessibility.

• Employment increased from 27,000 to 90,000 (notes).

Success: Investment, employment and environmental improvements.

Limitations:

• New jobs required skills many locals lacked.

• Expensive housing excluded original residents.

• Social inequality and community tensions.

How do mega-events promote urban reimaging? Compare London 2012 and Rio 2016 Olympics.

London 2012:

• Regenerated East London.

• Improved transport, housing and sporting infrastructure.

• Queen Elizabeth Olympic Park provided a long-term legacy.

Rio 2016:

• High costs and underutilised facilities.

• Displacement and socioeconomic inequalities.

• Environmental and governance problems.

Evaluation: Mega-events can enhance global visibility but do not guarantee sustainable regeneration.

How does urban greening contribute to sustainable urban reimaging?

Environmental:

• Reduces urban heat island effects.

• Improves air quality and biodiversity.

Social:

• Provides recreational spaces.

• Improves health and well-being.

Economic:

• Attracts tourism and investment.

• Improves city attractiveness.

Limitation: Rising property values may cause green gentrification and displacement.

How has Singapore used urban greening to improve sustainability?

• Gardens by the Bay: Tourism, greenery and city image.

• Bishan–Ang Mo Kio Park: Naturalised river, recreation and flood management.

• Punggol Waterway Park: Recreation and waterfront greenery.

• Skyrise Greenery: Rooftop and vertical vegetation.

• Park Connectors: Connect parks and encourage walking/cycling.

• Nature Ways: Improve biodiversity and ecological connectivity.

Evaluation: Integrates environmental sustainability, liveability and urban attractiveness.

Why might urban reimaging strategies fail?

• Top-down planning → local needs ignored.

• Gentrification → displacement of low-income residents.

• Unequal benefits → investment benefits wealthier groups.

• High costs → financial burden.

• Poor governance → ineffective implementation.

• Lack of community participation → weak local support.

Overall evaluation: Sustainable reimaging requires economic revitalisation alongside social inclusion, environmental improvement and community participation.