Megacity Growth in the Developing World
What is a megacity?
A megacity is a metropolitan area with a population exceeding 10 million people. In 1950 there were only 2 (New York, Tokyo); by 2025 there are 43, with most growth occurring in the Global South (Asia, Africa, Latin America). By 2050, two-thirds of the world's population will live in cities.
Global urbanisation patterns (T3.1 link)
- HICs: already highly urbanised (UK 84%, USA 83%); urbanisation is slow or stable.
- LIDCs/EDCs: rapid urbanisation driven by rural–urban migration and natural increase. Africa is urbanising fastest (~4% per year).
- Counterurbanisation occurs in some HICs as people leave cities for rural areas (push: congestion, cost; pull: improved transport, remote work).
Why do megacities grow so rapidly?
Rural–urban migration (the main driver)
- Push factors (from rural areas): agricultural mechanisation → unemployment; low wages; lack of services (hospitals, schools); drought, flooding and land degradation; conflict.
- Pull factors (to cities): higher wages and job opportunities; better healthcare and education; social networks (chain migration — people follow family/friends already in the city).
Natural increase
- Young migrants have children in cities → birth rate exceeds death rate → population grows even without net in-migration. This becomes a growing driver over time.
Case study: Mumbai, India — EDC megacity
Location and context: India's financial capital; situated on a peninsula on the west coast; population ~21 million (Greater Mumbai) and growing. Part of the state of Maharashtra.
Site and situation
- Built on a series of islands now joined by land reclamation; surrounded by sea on three sides → physically constrained.
- Deep natural harbour → historical trading significance; British colonial capital for western India.
Economic opportunities
- India's commercial hub: home to the Bombay Stock Exchange, Reserve Bank of India, Bollywood film industry.
- Major manufacturing (textiles, chemicals, pharmaceuticals) and services sector.
- Middle class of ~6 million; growing IT and financial services.
Challenges
Housing:
- Dharavi — one of Asia's largest informal settlements (slums): ~1 million people in 2.4 km² (density ~300,000/km²). Temporary/makeshift shelters; corrugated iron and plastic sheeting.
- Lack of security of tenure — residents can be evicted; investment in improvement is risky.
- Growing luxury apartment market alongside slums — extreme inequality visible.
Services and infrastructure:
- Water supply unreliable — piped water available only 3–5 hours per day in many areas; residents pay premium prices to private vendors.
- Sewage: only ~50% of waste treated; 40% of population has no toilet access → open defecation risks.
- Transport: suburban railway carries 8 million passengers/day (world's busiest); chronic overcrowding (3× designed capacity).
Employment:
- Formal employment cannot absorb all migrants → large informal economy: street vending, waste-picking (Dharavi has a $1 billion/year recycling industry), domestic work.
- Informal workers earn low wages, lack legal protections, face exploitation.
Environment:
- Air quality: vehicle emissions + industrial pollution → Mumbai regularly exceeds WHO PM2.5 limits.
- Mangrove destruction along coastline for development → reduced coastal protection.
- Flooding: monsoon rains (June–September) flood low-lying informal areas; Dharavi on low ground — 2005 floods killed >1,000 in Mumbai.
Sustainable urban management in Mumbai
- Dharavi Redevelopment Project: controversial plan to demolish and rebuild Dharavi with high-rise towers; residents to get free apartments (min 300 sq ft) in exchange for land. Critics: towers unsuitable for cottage industry; community disruption.
- BRIMSTOWAD flood management: underground storm drains and pumping stations to reduce monsoon flooding.
- Mumbai Urban Transport Project: rail expansion, bus rapid transit, increased metro lines.
- Slum Sanitation Programme: community toilets (1 per 25 families); awareness campaigns; reduced open defecation.
Comparison with Lagos, Nigeria — LIDC megacity
| Factor | Mumbai | Lagos |
|---|---|---|
| Population | ~21 million | ~15 million (official) / ~25 m (est.) |
| Country HDI | 0.644 (India) | 0.548 (Nigeria) |
| Main economy | Finance, IT, Bollywood | Oil, trade, services |
| Informal housing | Dharavi | Makoko (water slum, 100,000+) |
| Governance | Mumbai Metropolitan Region Development Authority | Lagos State Government (capacity-strained) |
| Water access | Intermittent piped water | Many without piped water; tanker dependency |
Lagos specific: sits on a low-lying lagoon; extreme flooding risk; Makoko "floating slum" — a water-based informal settlement; rapid growth of 600,000/year; government demolitions vs community resistance.
Edexcel B exam tip
The spec says "a megacity in a developing or emerging country." Choose one consistently (Mumbai or Lagos, not both mixed). Know: location, site/situation, structure, challenges (housing, services, employment, environment) and opportunities, and at least one sustainable management strategy with an evaluative comment (has it worked?).
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