characteristics of cities
centripetal movements
moving inwards towards centers; migrations into cities from smaller towns
rural push factors and urban pull factors
Rural push factors
High rates of population growth have put pressure on natural land resources such as water and energy and reduced the size of land holdings until they become unproductive. New farming technology has favoured the rich farmer but, for those at the other end of the socio-economic scale, unemployment or underemployment are typical.
Urban pull factors
Higher wages and more varied employment and education opportunities. Immigrants are willing to tolerate poor living conditions initially, in the hope for a better future. The attraction of “bright lights” are often cited as a pull factor, but the reality is that many migrants are intimidated by the urban environment and would prefer the tranquility and security of their original community.
centrifugal movements
decentralisation: outward moving populations from the centre of the city to its periphery, resulting in an expansion of the city.
Suburbanisation is the outward growth of towns and cities to engulf surrounding villages and rural areas. It is the result of rapid urban population growth and a demand for better housing and more space. Rising disposable incomes have enabled people to meet both the cost of new housing and the associated transport costs of commuting back to the city centre for work, which is global trend.
Industrial decentralisation may also occur, providing more work in the periphery. Congestion, pollution and lack of community may be the push factor.
family life cycle
A person is likely to move around different zones of the city, depending on their age and their need for a house of a certain size.
economic growth in (mega)cities
Urban economies are almost always more productive than rural ones. Most of the wealth is produced in megacities. 2% of China’s population lives in Shanghai, a city that produces 12% of the country’s output. Industrial activity is higher in cities because of greater efficiency; there will be a large, concentrated, educated, accessible, skilled workforce.
Megacities are large metropolitan areas or urban agglomerations of 10 million citizens or more.
LEDCs now hosts more megacities the MEDCs. Megacities bring together people and resources, and are able to generate wealth efficiently through economies of scale. Many would classify as world cities, global hubs for dynamic economic activity, social interaction and innovation.
Common problems include:
case study: megacity
Shanghai
measuring residential segragation
using the location quotient (LQ)
For example:
LQ < 1 means no concentration
reasons behind segragation
measuring deprivation (lack of benefits)
physical indicators — such as quality of housing, levels of pollution, incidence of crime, vandalism, graffiti
social indicators — including crime (reported and fear of), levels of health and access to health care, standards of education
economic indicators — access to employment, unemployment and underemployment, levels of income
political indicators — opportunities to vote and to take part in community organisation
why are informal economies growing?
+ pros and cons
It is an inevitable outcome of rapid urbanisation.
Informal economies employ more than 60% of the urban population in South America and Asia and more than 70% in sub-Saharan Africa.
Most of the time they are unskilled and poorly paid employees.
Advantages
Disadvantages
case study: informal economies
Dharavi, Mumbai

Its population has achieved a unique informal “self-help” urban development over years, without any external aid.
…
case study: overcoming housing problems
Mumbai and nanohomes outside cities
In conclusion, there is no easy solution to Mumbai’s housing problems.
pros:
cons:
Large cities are attractive for industries because:
main components and causes of the Brown Agenda (environemtal issues) in cities
+ the case with Mexico City
The greatest concentration of environmental problems occurs in cities experiencing rapid growth, such as Mexico City.
main components:
In the case of Mexico City, it is a basin where cool air can remain trapped by a larger layer of warm air above it: temperate inversion. The air fails to mix and vehicle emissions create intense pollution. Ozone is a byproduct, and is a strong respiratory irritant (causing discomfort).
consequences of urban heat island intensity (mircoclimate)
the difference in temperature between the urban and the surrounding rural area, which is usually 2-4°C and causes:
case study: urban heat waves
a growing problem, affecting cities irrespective of their latitude and climate type with high death rates
In the daytime, in stark contrast to rural areas, intense solar radiation heats the ground surface. The weather it typically anticyclonic — clear and calm — during heat waves.
For instance, during the Paris heatwave of 2003, a persistent anticyclone over Europe blocked rain-bearing winds from the North Atlantic, allowing hot air from North Africa to penetrate. It killed 30 000 people in Europe, most of them in cities where heating was most intense. 9 consecutive days of more than 38°C caused dehydration and cardiovascular lines, and high levels of ground-level ozone and nitrous oxides induced or aggravated respiratory problems. Most afflicted were the elderly and people with pre-existing health problems. Because intense heat never experienced by Europe, air conditioning was not common, even in hospitals. The french “heatwave emergency plan” was successful but not a long term solution over overheating cities.
causes and features of social urban stress
rapid expansion of urban populations, particularly in developing countries, overwhelms the abilitiy of cities to provide adequate and fair services like
What adds to social urban stress is:
elements of housing management
types of actors in crime
+
causes of crime and violence
Causes:

consequences of urban crime
Endemic insecurity can generate a culture of fear, leading to segregation and social fragmentation and the creation of fortified spaces. Tourist and FDI are dramatically reduced.
Gated communities
While high levels of violence do occur, anxiety generated by the perception of crime and endemic violence often outstrips the actual level of danger. Gated communities predominate where inequalities are pronounced and public security is inadequate. Most are found in North America, South Africa, and Brazil. Unfortunately, this often results in segregation along ethnic, religious or racial lines.
benefits of compact cities
vertical development and urban biocapacities
cities like Toyko, use less than the average biocapcity of 1.7 hectars per person due to vertical development - using land in several ways at the same time, in contrast to extended cities, as seen in Australia or US.