Primate city: a city that dominates the urban system, government, economy and culture of a region or country. Primate cities are much larger than the second-ranking urban centres.
Mega-cites are defined by the United Nations as those cities with a population exceeding 8 million people.
While size is the easiest criteria by which to define a mega-city, it is not a good measure of a city’s economic, cultural and political importance. Eg London is ranked 25th in terms of population but is a world city. The largest cities are no longer the most important cities in the global economy.
Mega-cities experience overurbanisation , that is, there are more urban residents than the economies of the cities can support. This is caused often by an influx of migrants. Overurbanisation occurs when large cities cannot provide enough jobs or raise enough revenue (via taxation) to provide the services that people need, eg access to freshwater.
The Challenges of Living in Mega-Cities
The challenges include: high rates of unemployment and underemployment; lack of adequate housing and shelter; health and nutrition problems; inadequate sanitation and water supplies; air, water and noise pollution; municipal budget crises; rising crime; a general deterioration of perceived quality of urban life; and damage to the ecosystem and cultural heritage.
High levels of unemployment and underemployment are characteristic of all the developing world’s mega-cities. According to the World Bank, about ¼ of the urban population in developing countries live in absolute poverty.
Because there are so few jobs in the formal economy, many of the urban poor are forced, or choose, to create their own employment within the informal sector. The informal economy plays an important role in the economy of the mega-cities. With such a large surplus of labour, the potential for exploitation is great, for example wages can be kept low and working conditions poor. The exploitation of child labour often takes place in the informal sector.
Population growth – both from natural increase and from rural-urban migration – is always ahead of the housing supply. As a result, the poor are forced to crowd into already squalid slums or squatter settlements. In Mexico city over 50% of the population live in slums or squatter settlements.
Strategies for meeting the housing needs of the urban poor include:
- Site-and-service projects . Schemes of this type involve the provision of tracts of urban land, which are divided into plots and provided with basic supporting services eg water, drainage and electricity. The plots are then either sold or leased to those who wish to build their own home on them.
- Upgrading projects . These schemes are usually designed for areas of the city that are already built up. The objective here is to transform areas that, although frequently developed illegally, provide shelter close to employment opportunities. Emphasis is placed on the installation of infrastructure, such as water and sewers, electricity, street paving and schools. An example would be the installation of a water pump for a small community to use.
- Core housing projects . These involve the construction of a simple concrete structure with water and toilet facilities. The occupants then complete the house themselves.
The advantages of these projects include the preservation of:
- Existing economic systems and opportunities
- Low cost housing stock in accessible locations
- Community and family support structures
The alternative – resettlement – is socially disruptive, usually occurs at a less accessible location and reduces access to informal employment.
Water and Sewage Problems
Sewage facilities are often ancient and inadequate. The proportion of the metropolitan population connected to the sewerage system in Manila is just 11%. Some cities are better off in this regard, eg 80% in Mexico City. Very little of the sewage collected is treated and is left to flow, untreated, into local waterways.
Solid-waste disposal services are also often inadequate. The proportion of sold waste collected in Mexico City is between 70% and 80%. In many cities the recycling of solid waste has become and important source of income for the very poor. In Beijing, the urban poor search through piles of waste in search of any recyclable material, earning approximately US$50 a month.
Providing the infrastructure for the collection and treatment of solid and liquid waste is often beyond the resources of many mega-cities. Initiatives promoting the recycling of waste materials not only contribute to a reduction in solid waste but provide a source of income for the urban poor.
Health and Nutrition Problems
Infectious and parasitic diseases associated with deficiencies in the physical environment, such as flimsy, overcrowded housing; air pollution; uncollected garbage; and dangerous workplaces.
Overcrowding is associated with the transmission of infectious diseases, such as colds. Lack of privacy can lead to mental health problems, contributing to stress, depression and a number of other psychological disorders. Food contamination associated with poor food preparation conditions and storage leads to the occurrence and transmission of infectious diseases. Food contamination leading to diarrhoea contributes to the premature death of children.
Rats, fleas and the bubonic plague (associated with rat infestations) are another factor in urban environmental health. The Black Plague occasionally exists in the developing world’s mega-cities.
Air, Water and Noise Pollution
One of the major challenges for developing world mega-cities is to clean up the pollution resulting from years of uncontrolled, unregulated industrial pollution. Such air pollution is commonly associated with acute and chronic illnesses, such as asthma.
One approach to mega-city development – especially programs designed to reduce pollution and health problems – is “knowledge-based development”, or city development that is more intentional, more planned, better coordinated and more purposeful. The people also play a vital role, in the form of self-help programs.
Responses to Challenges
The major needs for the future, according to the UN, are:
- To strengthen local government and to make it more effective
- To implement new approaches for alleviating poverty through local job promotion
- To develop supporting communities
- To make cities more environmentally friendly
Community based approaches, utilising the expertise and experience of nongovernmental organisations (NGOs), will be central to any sustained improvements. In parts of Karachi (Pakistan) 700,000 residents benefit from NGO efforts to provide water pipes, septic tanks and sewage systems in unauthorised (squatter) settlements.