IB Geography 1.2.2 Consequences of Megacity Growth Notes

Megacity Growth Reaches Individuals and Societies in Different Ways

1. For an individual, growth changes income, housing, travel time, health and personal safety.
2. For a society, it changes the demand on infrastructure, service budgets, land prices, governance and the shared environment.
3. The two do not move in the same direction at the same time.
   1. A migrant can raise their own earnings while adding to a traffic load that every commuter pays for.
   2. A city can raise its output while the households producing that output live without a legal water connection.

Individuals Gain Income and Choice While Paying in Time, Health and Risk

1. What Individuals Gain
   1. An urban labour market is larger and more varied, so a worker has more employers to choose between.
   2. The World Bank's 2023 Lagos diagnostic estimates that Lagos holds about 8 percent of Nigeria's population while generating between 15 and 30 percent of national GDP.
   3. About 3.2 million micro, small and medium enterprises employ roughly two-thirds of the state's working population.
   4. Those totals show where economic activity is concentrated rather than proving that every migrant gains a secure income.
   5. Schools, clinics, piped water and electricity cost less per household to deliver where households sit close together.
   6. Finance, trade, transport, ICT, manufacturing and entertainment provide work that is less available in many rural areas.
2. What Individuals Pay

1. New arrivals reach the city faster than legal housing is built, so they rent or build in informal settlements.
2. Residential density in Mumbai peaks in the middle of the island city, around Marine Lines and Bhuleshwar, rather than at the southern tip in Colaba and Fort.
3. Housing keeps spreading north and east along the suburban rail lines, which lengthens the daily journey for each new cohort of arrivals.
4. Indian Railways plans that network to a super-dense crush load of 14 to 16 standing passengers per square metre.
5. The Government Railway Police recorded 2,468 deaths on the network in 2024, including 1,151 people crossing the tracks and 570 who fell from moving trains.

Housing Runs Short First, and Residents Build the Response Themselves

1. The UN's Sustainable Development Goals report of 2024 counted 1.12 billion people living in slums or informal settlements in 2022, which was 24.8 percent of the world's urban population.
2. Informal does not mean unbuilt, because these are dense districts with shops, workshops, rented rooms and landlords.
3. What residents lack is legal recognition of the land they occupy.
   1. Insecure tenure means one eviction can remove a household's home and its workplace together.
   2. It also discourages a household from improving a structure it could lose.
   3. Utilities often refuse a connection to an address with no legal holding number, so residents buy water and power from intermediaries.
4. Residents organise, negotiate and build rather than wait to be provided for.
   1. In Mumbai, the federation of SPARC, the National Slum Dwellers Federation and Mahila Milan has built 366 community toilet blocks holding 6,952 toilets since 1993, serving more than 350,000 people.
   2. Those blocks are designed and managed by the residents' own organisations.
5. Informal districts also carry part of the city's productive economy.
   1. Dharavi occupies about 2.4 square kilometres of central Mumbai between two suburban rail lines.
   2. Its workshops handle recycling, leather work, pottery and garment stitching.
   3. They supply firms in the formal economy, so the district is a supplier to the city rather than a separate enclave.

A Megacity Concentrates the Gains and Spreads the Costs

1. What A Society Gains
   1. Firms cluster where suppliers, customers and skilled workers are close, which raises output per worker.
   2. A megacity therefore contributes a larger share of national output than of national population.
   3. Density lowers the cost per household of a water main, a bus route or a fibre line.
   4. Tax revenue concentrates in the same place, which gives government the means to build.

1. What A Society Pays
   1. Roads, drains, pipes and treatment plants are built on a slower timetable than population arrives on.
   2. The World Bank reports that 98 percent of trips in Lagos use roads, while commuters spend an average of four hours a day in traffic.
   3. Time lost in congestion reduces earnings, care time and productivity for both households and firms.
   4. Air quality falls where vehicle exhaust, construction dust and brick kilns concentrate in one airshed.
   5. World Bank estimates link ambient air pollution in Lagos to about 11,200 premature deaths in 2018.
   6. Where public networks cover a minority of households, families must pay vendors, drill boreholes or rely on packaged water.
   7. The World Bank's 2023 Lagos diagnostic estimated that only 35 percent of residents had access to the public water supply.
   8. The same diagnostic estimated that only 5 percent were connected to the public sewerage system.
   9. Poor drainage and dumped waste block channels, so intense rainfall can turn a service gap into a flood hazard.
   10. Land prices rise fastest where access is best, which pushes low-income households to the edge or into informal districts.
   11. One city can hold several different service standards at once, so inequality becomes a feature of the built environment.
2. What Government Faces
   1. A megacity usually crosses several municipal boundaries, so no single authority governs the whole built-up area.
   2. Planning, transport, water and policing can each sit with a different body at a different scale.
   3. Coordination failure then shows up as duplicated projects and as districts nobody is accountable for.

Lagos: Economic Growth Outpaces Housing, Water and Transport

1. Scale And Speed
   1. UN World Urbanization Prospects 2025 estimates that Lagos grew from 7.9 million people in 2000 to 12.8 million in 2025 and projects 16.2 million by 2050.
   2. The 2025 revision uses a harmonized Degree of Urbanization method, so its city series should not be joined to the older urban-agglomeration estimates used in the 2018 revision.
   3. Across the 2000 to 2025 series, the UN calculates an average annual growth rate of 1.92%.
   4. A World Bank diagnostic reported Lagos State growth of 3.2% a year, but the wider state boundary is not directly comparable with the UN city series.
   5. At 1.92% annual growth, a population would double in about 36 years if the rate stayed constant.

1. Housing, water and transport must therefore expand while demand is still accelerating.

1. Why The Megacity Keeps Growing
   1. Natural increase adds population because Nigeria's young age structure produces more births than deaths.
   2. Rural-to-urban and urban-to-urban migration add people seeking jobs, education and services.
   3. Lagos attracts migrants as Nigeria's main centre for finance, trade, ports, manufacturing, ICT and entertainment.
   4. The World Bank estimates that the informal sector contributes about one-third of the Lagos economy.
   5. Informal work creates entry-level livelihoods but often provides unstable income, weak legal protection and no social insurance.
2. Named Districts Under Pressure
   1. Lagos Island, Marina, Victoria Island and Ikoyi contain major offices, banks and higher-income housing at the economic core.
   2. Apapa concentrates port activity, jobs and freight traffic, so queues of trucks add to road congestion and air pollution.
   3. Makoko is a lagoon-side informal settlement where insecure tenure and limited water and sanitation increase household risk.
   4. Ikorodu combines rapid peripheral growth with steel plants, a dumpsite, blocked drains and recurrent flooding.
   5. Olusosun is the city's largest overloaded dumpsite, linking weak waste collection to smoke, odour and contaminated runoff.
   6. Lekki represents fast formal expansion along a low-lying coast exposed to urban flooding and coastal erosion.
   7. Metropolitan growth extends toward neighbouring Ogun State, so journeys and housing markets cross the boundary of Lagos State.

Where Lagos's Growth Outran Housing, Water and Transport

1. Housing, Water And Flood Risk
   1. The World Bank's 2023 diagnostic estimated a housing deficit of about 3.3 million units.
   2. It estimated that 50 to 75 percent of residents lived in informal housing.
   3. Only 35 percent of residents had access to the public water supply, so households often depended on vendors, boreholes or sachet water.
   4. Only 5 percent were connected to public sewerage, which left most waste to septic tanks, informal disposal or untreated discharge.
   5. The diagnostic estimated annual damage from river and urban flooding at almost US$4 billion.
   6. It estimated a further US$1.7 billion a year in coastal damage.
   7. Waste collection reached only 20 to 30 percent of the waste stream in the same assessment.
   8. Discarded plastic and solid waste block drains, which increases flood exposure in low-lying districts.
   9. The losses are shaped by planning, housing quality and service access rather than population size alone.
2. Transport And Air Pollution
   1. Road transport carries 98 percent of trips, while commuters spend an average of four hours a day in traffic.
   2. A World Bank study estimated that ambient air pollution caused about 11,200 premature deaths in 2018.
   3. Illness and premature deaths from that pollution cost about US$2.1 billion, equal to 2.1 percent of Lagos State's GDP.
   4. Road vehicles, industrial emissions and diesel generators are major sources, with open burning and illegal waste dumping adding more particles.
   5. Low-income households bear more of the cost because they have less choice over housing location, water source and exposure to polluted roads or drains.
3. What The City Has Built In Response
   1. Lagos opened a 22-kilometre bus rapid transit corridor in March 2008, the first dedicated BRT route in sub-Saharan Africa.
   2. The initial system used 220 buses and carried more than 200,000 passengers a day.
   3. The Blue Line was inaugurated in 2023 and the first 37-kilometre phase of the Red Line was inaugurated in February 2024 with seven stations from Agbado to Oyingbo.
   4. These corridors expand capacity, but they do not remove the housing, water, sewerage and drainage deficits across the whole metropolitan area.

Who Gets Harmed Depends on Position, Not Only on Exposure

1. Two households in the same megacity can meet the same hazard and come out of it differently.
2. Exposure is the physical fact of standing in the path of a flood, a fire or polluted air.
3. Vulnerability is the social position that decides whether a household can avoid, absorb or recover from it.
   1. A tenant without legal tenure cannot claim compensation for a house the city does not recognise.
   2. A daily wage earner loses income on a day spent at home, which a salaried worker does not.
   3. A household with a piped supply is not exposed to the price a water vendor sets after a failure.
4. Treating urban risk as purely physical leads to policy that moves people, when the problem is often what those people are entitled to.
5. The same reasoning explains why a benefit is distributed unevenly.
   1. A metro line raises access for households within reach of a station and leaves the rest of the city where it was.
   2. Rising land values pay owners and raise rents for tenants.