Mega-Cities: Comprehensive Study Notes

Global Population & Urbanisation Trends

• World population currently rising by 86\,\text{million} people per year; momentum will keep growth positive for several decades because large cohorts have not yet reached child-bearing age.
• Distinct regional patterns:
  • Developed regions: population has stabilised and is projected to fall slightly in the next century.
  • Developing regions: population is rapidly increasing (see Fig. 1 – growth curves for “Developed regions” vs. “Developing regions”).
• Urbanisation (share of people living in towns/cities):
  • Between 1990 and 2025 the urban population is expected to double from 2.5\,\text{billion} to 5\,\text{billion}.
  • 90\% of this increment will occur in Africa and Asia.

Definition & Evolution of Mega-Cities

• Mega-city = urban agglomeration whose population exceeds 8\,\text{million}.
• Historical milestones (Table 1):
  • 1950: only 2 mega-cities – New York & London.
  • 1990: 20 mega-cities, 14 in the developing world.
  • 2000 (projection): 25 mega-cities, 19 in the developing world.
• Growth comparison: although mega-cities are huge, the fastest percentage growth usually occurs in “million-cities” (population 1–10\,\text{million}).

Spatial Distribution: Coastal vs Non-Coastal Cities (Table 2)

• 108 coastal cities (population 1–10\,\text{million}) vs 159 non-coastal in 1995.
• Among settlements >10\,\text{million}, coastal locations dominate (no exact count given, but described as “disproportionate”).
• Implication: coastlines experience high environmental pressure – habitat loss, biodiversity decline, erosion of natural storm-protection systems.

Current Urban Growth Rates (Selected Examples)

• Dhaka 7\%\;\text{yr}^{-1}
• Lagos 5.6\%\;\text{yr}^{-1}
• Delhi 4.6\%\;\text{yr}^{-1}
• Anticipated African national urban population growth: Kenya 6.2\%, Tanzania 6.0\%.
• Latin American mega-cities show a marked slow-down (Fig. 2) with annual growth falling in successive decades for Buenos Aires, Mexico City, Lima & Rio de Janeiro.

Environmental Challenges in Developing-World Mega-Cities

• Water access: >1\,\text{million} residents in Jakarta lack piped water/wells; 30\% depend on an over-drawn aquifer → land subsidence.
• Air quality: Jakarta exceeds WHO particulate limits for 8 months per year; similar chronic pollution in Mexico City, São Paulo, Calcutta & Bombay.
• Waste & sanitation:
  • Lagos, Jakarta, Lima: worst solid-waste collection records.
  • Bangkok, Manila, Dhaka: acute sewage-disposal problems.
  • Mexico City: aquifer over-abstraction has caused 7.5\,\text{m} subsidence in 100 yrs; aquifer also contaminated by sewage.
• Coastal siting exacerbates ecosystem degradation (mangroves, coral, wetlands).

Environmental & Resource Issues in Developed-World Mega-Cities

• Primary concern shifts from local shortages to massive per-capita resource consumption and resulting regional/global impacts (GHG emissions, ecological footprint).
• Air pollution still a direct health issue (e.g.
  Los Angeles, Tokyo), but often better regulated than in developing cities.

Common Social Problems

• Violence, crime, drug abuse present in both rich and poor mega-cities; not strictly proportional to size but influenced by inequality and governance.
• Dual-city phenomenon: pronounced class segregation → elite enclaves vs vast low-income zones.
• Multi-jurisdictional governance: no Latin-American mega-city has a single all-city authority; coordination is weak.

Nine Key Drivers of Mega-City Growth

1. Colonial foundation of coastal cities by European powers (e.g.
   Lima, Buenos Aires, Rio de Janeiro 1763).
2. Port & trading functions for specific commodities (Shanghai – cotton/silk; São Paulo – coffee).
3. Capital-city designation or administrative reassignment (Dhaka: population jump from 0.43 M in 1950 to 2.3 M in 1975, now growing 7.25\%\,\text{yr}^{-1}).
4. Post-independence industrialisation & import-substitution favouring major urban nodes (Mexico City, Rio, Buenos Aires, Indian metros).
5. Post-war modernisation (1930s Great Depression & WWII) stimulated local industry and wealthy domestic markets in Latin America.
6. Declining urban & rural mortality through public-health advances raised natural increase and lengthened life expectancy.
7. Rural-to-urban migration under classic push–pull forces:
   • Lack of land, agrarian mechanisation, conflict, famine (push).
   • Jobs, services, perceived higher living standards (pull).
     Example: contributed 50.8\% of Argentina’s urban growth 1947–1960.
8. Settlement laws (e.g.
   China’s household registration – “Entitled” urban vs “Non-Entitled” rural) created privileged urban status → migration pressure.
9. Globalisation & foreign direct investment concentrate in biggest cities: Bangkok 86\% of Thailand’s GNP in finance/real estate, 74\% of manufacturing; Lagos hosts 40\% of Nigeria’s highly-skilled labour though only 5\% of population.

Advantages of Mega-Cities (Table 3)

• Agglomeration economies: clustering of industries/finance gives ready markets, labour, external linkages.
• Infrastructure & services usually superior to rural areas (roads, power, piped water, education, health, family planning).
• Health outcomes: urban infant-mortality lower, life expectancy higher (Brazil 75.4/1000 urban vs 107.5/1000 rural in 1986; Peru 57.9/1000 vs 104.1/1000).
• Informal sector offers entrepreneurial niches and absorbs surplus labour.
• Auto-construction/self-help housing allows incremental expansion & rental income.
• Dense social/employment networks in shanties underpin informal economy.
• Grass-roots governance potential – e.g.
  Bombay’s chawls; service privatisation (supported by World Bank) can relieve public budgets.
• “Concentrated de-concentration” policies push firms to city edge to develop peripheral sub-centres (Buenos Aires example).

Disadvantages Intensified by Size

• Migrant magnet effect outpaces job creation & infrastructure (e.g.
  Lagos as Nigeria’s primary city).
• Unequal service distribution: in São Paulo 40/54 public hospitals located in wealthy districts → poor health outcomes for majority.
• Severe environmental hazards (water, air, waste, land subsidence, coastal habitat loss).
• Informal sector often harassed, lacks credit/support, and adds little to national revenue.
• Urban sprawl via motor-car use & spontaneous settlement (favelas, pueblos jóvenes, bustees) undermines formal planning, inflates land prices (São Paulo).
• Hazardous land occupation: landslides in Rio’s Rocinha; flooding in Calcutta.
• Administrative fragmentation complicates metropolitan governance.
• Social dualism – polarised wealth & spatial segregation reinforce inequality.

Case Study 1: Bombay (Mumbai)

• Population trajectory (Fig. 3): >13\,\text{million} in 1994; projected 15\,\text{million} by 2000.
• Physical setting: 180\,\text{sq mi} formed by reclaiming 7 islands; Western Ghats crossed by rail (1850s).
• Historical growth: English deep-water port (received 1661); cotton export to Lancashire after 1850.
• Present social fabric:
  • \approx50\% residents live in slums/chawls; many homeless by UK standards.
  • Dharavi: <1\,\text{sq mi}; \sim700,000 people; 77\% households average 5.3 persons/room.
• Economy: vibrant informal industries – jewellery, pottery, cloth & a major recycling sector.
• Infrastructure deficits:
  • 2\,\text{million} people without sewers; city produces 5,000\,\text{t} rubbish/day.
  • 550\,\text{million gal} drinking water piped 100\,\text{mi} daily.
  • Untreated sewage discharged into Arabian Sea; industrial pollution → respiratory/skin diseases.

Case Study 2: Shanghai

• Early development: regional port; 1.2\,\text{million} by 1910.
• Japanese occupation 1937–1949 caused foreign exodus.
• Communist era: anti-urban & anti-foreign trade policies; many industries relocated; nationalisation.
• Household registration system: “Entitled” urban residents received subsidies → migration surge; crackdown in late 1950s.
• Cultural Revolution forced youth/skills to rural areas → under-urbanisation.
• Post-Mao reform (1978 on): foreign investment welcome; population growth 3.8\% p.a. (1985–1993).
• “Floating population”: large, often illegal, unregistered migrants complicate housing & service planning.
• Economy: 67\% industrial-output growth 1990–1993 but low-skill factories relocating outward; unemployment 15–20\%; 40\% families lack basics.

Case Study 3: São Paulo

• MASP = 39 municipalities; \sim17\,\text{million} residents; delivers 30\% of Brazil’s GNP; \frac{1}{3} of labour force in manufacturing → 2nd-largest industrial city worldwide.
• Historical stages:
  • Founded 1554; minor until late 19^{\text{th}} century (Rio dominant).
  • Coffee boom → annual growth 13.9\%; social stratification via employer-provided housing.
  • 1910–1930 elite moved to Higienópolis; Haussmann-style boulevards displaced poor to periphery.
  • Import-substitution industries 1920–1930; further industrialisation 1960s–1980s plus nationwide transport upgrades.
  • 1980s: major banks relocated from Rio; but economic crisis triggered industrial de-concentration.
• Four core–periphery dynamics (mid 20^{\text{th}} century):
  1. Falling density: 110\rightarrow24.5 persons/ha (1914\rightarrow1960); peripheral growth 10\%\,\text{yr}^{-1}.
  2. Class segregation: wealthy centre vs poor periphery.
  3. Rising home-ownership overall (19\% → 53.8\% 1920\rightarrow1970) via self-build in periphery & condos in core.
  4. Dual transport: buses for poor, cars for rich.
• Economic crisis metrics (Table 4): unemployment rose from 12.4\% (1985) → 15.4\% (1993); absolute unemployed 0.8\,\text{M} → 1.224\,\text{M}.
• Housing: \approx\tfrac{2}{3} of homes in favelas by 1992.
• Environmental stress:
  • WHO particulate & CO limits breached \ge6 months/yr.
  • 800\,\text{t} raw sewage plus industrial effluent enter River Tietê daily.
  • 28\% homes lack piped water; 50\% not sewered.

Synthesis: Towards Sustainable Mega-Cities

• Essential policy thrusts:
  • Community participation (Shanghai, Guangzhou) for planning legitimacy.
  • Legalise informal settlements; extend tenure security to encourage upgrading.
  • Facilitate micro-credit & recognise informal enterprises to integrate them into formal economy.
  • Invest in basic urban services (water, sanitation, waste, mass transit) before further outward expansion.
  • Narrow urban-rural and intra-urban income gaps to temper migration “pull”.
  • Apply stricter environmental standards (vehicle emissions, industrial effluent) & protect coastal ecosystems.
  • Promote “concentrated de-concentration” / polycentric development to share growth regionally.
  • Strengthen metropolitan governance frameworks to coordinate across multiple municipalities.

Key Figures & Tables Recap

• Fig. 1: World population growth 1750–2150 showing divergence of developed vs developing regions.
• Table 1: Evolution of >8\,\text{M} cities 1950, 1970, 1990, 2000.
• Table 2: Coastal vs non-coastal >1\,\text{M} cities (1995).
• Fig. 2: Latin-American city growth rates by decade 1950–1990.
• Table 3: Advantages & disadvantages of mega-cities.
• Figs. 3–5: Population growth curves for Bombay, Shanghai & São Paulo respectively; Table 4 unemployment data for São Paulo.

Ethical & Practical Implications

• Equity: spatial segregation fosters social exclusion → moral imperative to create inclusive service delivery and economic opportunity.
• Health: uncontrolled pollution violates right to health; policy must balance growth with public-health safeguards.
• Environmental justice: poorest groups often inhabit hazard-prone land yet contribute least to pollution – call for remedial infrastructure & land-use planning.
• Global responsibility: developed-world mega-cities’ consumption patterns drive worldwide ecological impacts (climate change) – need for sustainable lifestyles & technology transfer.