Urbanisation and mega-cities: HSC Geography 2022 Focus Area

Note: This page is part of the HSC Geography 11-12 (2022) syllabus, first examined in HSC 2025. The legacy 2009 syllabus Urban Places content is preserved as reference in the sibling urban-places/ folder.

What this sub-topic is asking

Rural and Urban Places asks you to investigate spatial patterns at different scales, identify drivers of change, and evaluate responses. Urbanisation is the dominant urban-side process at global scale; mega-cities are its most visible expression. You need a global pattern, named drivers, named challenges, and at least one developed-world plus one developing-world case study.

The answer

Urbanisation is the increase in the proportion of a population living in urban places. Mega-cities are cities with a population over 10 million (UN definition; some sources use 10 million metropolitan, others 8 million urban agglomeration).

Global spatial pattern

• 1950: approximately 30 percent of world population was urban; 2 cities (Tokyo, New York) over 10 million.
• 2020: approximately 56 percent urban; 33 mega-cities (UN World Urbanization Prospects 2018).
• 2050: projected approximately 68 percent urban; over 40 mega-cities, with most growth in Africa and Asia.

The spatial distribution shifts. Early industrialisation produced urban growth in Europe and North America. Late-20th-century urbanisation centred on East Asia (Tokyo, Shanghai, Beijing, Seoul, Manila). Current and projected growth is concentrated in South Asia (Delhi, Karachi, Dhaka, Mumbai) and sub-Saharan Africa (Lagos, Kinshasa, Cairo, Luanda).

Drivers of urbanisation

Rural-urban migration

People move to cities for economic opportunity, education, health services, escape from rural conflict or environmental degradation. The dominant driver in late-industrialising economies.

Natural increase

Birth rates in urban populations often exceed death rates, particularly where rural-urban migrants are of reproductive age. Especially significant in sub-Saharan African mega-cities.

Economic restructuring

As economies move from agriculture to manufacturing to services, the spatial logic shifts: services and high-productivity manufacturing concentrate in urban centres, pulling labour.

Reclassification

Some urbanisation is statistical: rural settlements grow to qualify as urban without people physically moving. This is a real driver in China's data.

Challenges of mega-city growth

Informal settlements (slums)

Approximately 1 billion people globally live in informal settlements (UN-Habitat). Lagos Makoko, Mumbai Dharavi, Rio Rocinha, Nairobi Kibera are flagship examples. Informal settlements typically lack secure tenure, sanitation, formal water, electricity, paved roads, and emergency services.

Infrastructure stress

Water supply, sanitation, electricity, transport and waste management struggle to keep pace with growth. The result: shortages, congestion, disease.

Liveability

Air pollution (Delhi, Beijing, Lahore among the world's worst), heat island effects, lack of green space, long commutes.

Inequity

Mega-cities concentrate wealth alongside extreme poverty, often spatially close (Sao Paulo's Paraisopolis favela borders the wealthy Morumbi suburb).

Environmental impact

Cities account for approximately 75 percent of global energy use and around 60-80 percent of CO2 emissions (varying by methodology). Mega-city emissions footprints have global climate implications.

Climate vulnerability

Many mega-cities are coastal (Jakarta, Mumbai, Lagos, Manila, New York) and face combined sea-level rise plus storm surge plus subsidence. Jakarta is partially relocating its capital function to Nusantara in Borneo, citing climate and sinking-land challenges.

Responses

National

Urban planning law, infrastructure investment, decentralisation policy (encouraging growth in second-tier cities).

City government

Master plans, public transport investment, slum upgrading programs, climate-adaptation infrastructure.

International

UN-Habitat's New Urban Agenda (2016) framework; Sustainable Development Goal 11 (Sustainable Cities and Communities); World Bank urban lending.

Civil society

Resident associations, NGOs working on slum upgrading and tenure security.

Examples in context

Example 1. Greater Sydney as a developed-world mega-city. Greater Sydney's population reached approximately 5.4 million in 2024; it is not yet a mega-city by the UN definition (10 million threshold) but is on a trajectory toward it by mid-century under current planning. Challenges include housing affordability (Sydney is consistently ranked among the world's least affordable cities relative to local income), transport pressure (Sydney Metro and WestConnex have not eliminated congestion), urban-fringe sprawl reaching the foothills of the Blue Mountains, and bushfire vulnerability on the western edge. Responses include the Greater Sydney Region Plan, three-cities strategy (Eastern Harbour City / Central River City / Western Parkland City), Sydney Metro investment, and Western Sydney Airport with the surrounding Aerotropolis. A strong response uses Sydney to show that "mature" mega-city governance has different challenges from those facing Lagos but is not free of them.

Example 2. Jakarta and capital relocation. Jakarta is sinking at up to 25 cm per year in some districts (groundwater extraction plus underlying soft soils), faces severe flooding, and is at extreme risk from sea-level rise. The Indonesian government has begun construction of a new capital, Nusantara, in East Kalimantan to relocate government functions. This is the world's largest planned capital relocation since Brasilia (1960). The case illustrates how mega-city environmental vulnerability can drive national-scale spatial policy decisions.

Try this

Q1. Define a mega-city and identify the current global mega-city count. [2 marks]

• Cue. A city of 10 million or more residents; approximately 33 mega-cities globally as of UN World Urbanization Prospects 2018 (rising to 40+ projected by 2050).

Q2. Analyse the drivers of mega-city growth, distinguishing between developed-world and developing-world contexts. [6 marks]

• Cue. Rural-urban migration; natural increase; economic restructuring; reclassification. In developing world (Lagos, Karachi), rural-urban migration plus high natural increase dominate. In developed world (Sydney, Tokyo), economic restructuring, immigration and natural increase dominate; rural-urban migration is small.

Q3. Evaluate the effectiveness of urban planning responses to mega-city challenges in a developing-world city. [8 marks]

• Cue. Pick Lagos (Eko Atlantic versus Makoko; BRT versus traffic). Or Mumbai (Dharavi redevelopment versus tenure security). Or Jakarta (capital relocation versus on-the-ground flooding). Apply scale, equity, sustainability. Reach a calibrated judgement; do not pretend any single response is sufficient.