Geography Urban cities -

what is a megacity how are they caused

population over 10 million people, a result of economic growth, rural-urban migration and high rates of natural increase.

• people migrate to the city in search of jobs, dominated by young adults

• as it grows becomes multi nuclei centres

impact of megacities

• requires new form of planning and management to cope with large sizes

• the environmental impact is greater, pollution

• increase in crime

why are megacities important

they generate wealth

in HIC’s, urban areas generate over 80% of national economic output, LIC’s 40%

how are levels of development measures

GNP per head

what functions do rural places have in development

• 1. Commercially, towns provide the market and exchange centres necessary for the conversion from subsistence to cash crops.

• 2. Industrially, towns may provide a stimulus for development – the larger the town the better it is for skilled and unskilled labour.

• 3. Politically, towns may provide a focus for nationalist feeling and also allow for ethnic, tribal and religious intermixing.

• 4. Administratively, towns provide economies of scale for health and education.

• 5. Socially, the intermixing may help weaken ties to traditional rural beliefs and customs.

what problems does economic wealth in a country lead to (deterioration manifested in)

• high rates of unemployment and underemployment, as urban labour markets are unable to absorb the growing number of job seekers

• insufficient housing and shelter, coupled with the growth of slums and squatter settlements

• overloaded and overcrowded transport systems

• air, water and noise pollution

• deteriorating infrastructure (basic services) and shortfalls in service

• delivery (public transport, waste disposal and health care)

• growing inequalities between areas or districts within a city in terms of access to infrastructure and services

• inadequate sanitation and water supplies and associated health problems

• increasing prevalence of social problems, such as rising crime rates, suicide rates, drug and alcohol abuse, family breakdown and homelessness

• a general deterioration in the perceived quality of life.

what are poor zones in a country, and where are they found

zones of deprivation, poverty and exclusion

• in developed countries in the inner-city like ghettos

• in developing countries in shanty towns that show worst conditions

how do we measure deprivation

• 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; (unemployment, disability, free school meals); proportion of lone-parent families

• economic indices – access to employment; unemployment and underemployment; levels of income

• political indices – opportunities to vote and to take part in community organization.

what is the definition of a slum

one or a group of people living under the same roof not having one or more of these conditions

1. durable housing – a permanent structure providing protection from extreme climatic conditions

2. sufficient living space – no more than three people sharing a room

3. access to improved water – water that is sufficient, affordable and can be obtained without extreme effort

4. access to improved sanitation facilities – a private toilet or a public one shared with a reasonable number of people

5. secure tenure – protection against forced eviction.

what is a formal economy

consists of

• offices,

• factories,

• commercial building,

often is foreign owned and produces goods and services for an elite population.

the civil service employs a large number of people

what is an informal economy

• servants

• gardeners

• maids

• cleaners

• taxi drivers

• prostitutes

it is small scale locally owned and labour intensive

it is often divided into two, traditional bazaar economy and street economy

what is a bazaar economy

The bazaar economy consists of small trade and service establishments, and craft workshops. Many bazaars are family enterprises employing children as well as the elderly.

• 45% of employment in city

producing cheap goods and services for low-income households. Intense competition between rivals keeps prices low and the activities normally

what is street economy

The street economy includes street hawkers, shoe-shiners, beggars, thieves and prostitutes.

• 40% of labour force

earnings and standards of living are low

exploitation of informal sector

rich are able to exploit the poor, the informal sector benefits the formal sector, since it keeps prices down.

what are some physical factors that influence urban residential areas

wealthier people can be near rivers or canals for views, or poor people when there is a risk of flooding

• in HIC’s building standards take into account the risk

• in areas of rapid growth and informal housing they may have to use any available site

what is positive segregation

an ethnic group gains advantages by being located in one place , there are enough to support services

what is negative segregation

certain groups are excluded from particular areas, because of cost, or redlining (illegal process where people prevent particular groups from locating there)

why is urban residential planning important what makes it difficult

to achieve balanced social mix of housing types dispersed around the city

rich neighbourhoods often resist development of socially affordable housing

what are four key points regarding cities in poor countries

• The rich generally live close to the city centre, whereas the poor are more likely to be found on poor-quality land, and on land that may be at risk from hazards, such as landslides and floods.

• Higher-quality land is occupied by the wealthy.

• Segregation by wealth, race and ethnicity is evident.

• Manufacturing is scattered throughout the city.

what is urbanization and cause

an increase in the proportion of people living in urban areas

caused by rural-to-urban migration, higher rates of natural increase in urban areas, reclassification of rural areas to urban areas

what is a natural increase

birth rate is higher than death rate , often occurs in cities with youthful age structure

what is rural-to-urban migration and occurrence

the movement of people away from countryside to towns and cities

it occurs because people believe they will be better off in urban areas with push and pull factors.

what is gentrification

the reinvestment of capital into inner-city areas. refers to an improvement of residential areas.

often where there are brownfield sites (eg, abandoned)

it can lead to social displacement of poor people as they can no longer afford them

what is re-urbanization or urban renewal

the revitalisation of urban areas, and a movement of people back into these areas.

what is suburbanisation

the outward expansion of towns and cities, mainly in europe, north america and australia, in thank to improved transport systems.

this grew the middle-class and residential suburbs. there were town expansions with these tram lines, declining price of farm land fro urban expansion

what is counter urbanisation

process involving the movement of population away from larger urban area to smaller urban areas, new town, new estates, on the edge or just beyond city limits.

what are some reasons people want to leave large urban areas and move to towns in rural areas

• high land prices

• congestion

• pollution

• high crime rates

• a lack of community

• declining services

what is urban sprawl

the uncontrolled growth of urban areas at their edge, suggests that urban areas grow in an unchecked fashion

green belts prevent this as they set a limit

what is urban system growth

as urban areas grow, there is an increase in demand of systems, water, sanitation, waste disposal, transport facilities, telecommunications

what is deindustrialisation

long-term absolute decline in employment in manufacturing sectors of an economy, decline in jobs not productivity.

factors:

● the exhaustion of resources

● the increasing costs of raw materials

● automation and new technology

● the introduction of a rival product

● fall in demand

● overseas competition from NICs

● rationalization

● a rise in costs

● the removal of a subsidy

● lack of capital.

what is positive deindustrialisation

occurs when industries reduce their workforce to increase productivity through mechanisation and rationalisation. This makes the industry more competitive.

what is negative deindustrialisation

occurs when particular industries decline without any compensating rise in productivity or mechanisation.

what is reindustrialisation

the growth of high-technology industries, small firms and services industries (tertiarization).

what are the two factors effecting the climate in an urban area

• The structure of the air above the urban area – more dust in the air means a greater concentration of hygroscopic particles, less water vapour, but more CO2 and higher proportions of noxious fumes from the combustion of fuel and discharge of waste gases by industry.

• The structure of the urban surface – more heat-retaining materials are used, with lower albedo and better radiation-absorbing properties. There are rougher surfaces with a great variety of perpendicular slopes facing different aspects. Tall buildings can be very exposed, while the deep streets are sheltered and shaded.

what are the resultant 6 processes

• radiation and sunshine

• clouds and fogs

• temperatures

• pressure and winds

• humidity

• precipitation

explain radiation and sunshine

• Greater scattering of shorter-wave radiation by dust, but much higher absorption of longer waves owing to surfaces and CO2, hence more diffuse sky radiation with considerable local contrasts owing to variable screening by tall buildings in shaded narrow streets.

• Reduced visibility arising from industrial haze.

explain clouds and fogs

• Higher incidence of thicker cloud cover in summer and radiation fogs or smogs in winter because of increased convection and air pollution, respectively.

• Day temperatures on average 0.6°C warmer.

explain temperatures

• Stronger heat energy retention and release, including fuel combustion, giving significant temperature increases from the suburbs into the centre of built-up areas, creating heat “islands”.

• Up to 1.5°C warmer during winter nights (snow in rural areas increases their albedo, thereby increasing the differences).

• Heating from below, increasing air mass instability overhead, notably during summer afternoons and evenings.

• Big local contrasts between sunny and shaded surfaces, especially in spring.

explain pressure and winds

• Severe gusting and turbulence around tall buildings causing strong local pressure gradients from windward to leeward walls.

• Deep, narrow streets much calmer unless aligned with prevailing winds to funnel flows along them – the “canyon effect”.

explain humidity

• Decreases in relative humidity owing to lack of available moisture and higher temperatures.

• Partly countered in very cold, stable conditions by early onset of condensation in low-lying districts and industrial zones

explain precipitation

• Perceptibly more intense storms, particularly during hot summer evenings and nights owing to greater instability and stronger convection above built-up areas.

• Probably higher incidence of thunder in appropriate locations.

• Less snowfall and briefer covers, even when uncleared.

what is urban heat island

as urban areas are warmer than the surrounding countryside average 2-4 Celsius creates heat island

• Wind speeds are lower due to the height of buildings and urban surface roughness.

• Burning of fossil fuels for domestic and commercial use can exceed energy inputs from the sun.

what is the heat island effect and effected by

the contrast between urban and rural areas is greatest under calm, high pressure conditions - city centre

• heat produced by human activity

• changes of energy balance: buildings have a high thermal capacity in comparison to rural areas – up to six times greater than agricultural land

• the effect on air flow: turbulence of air may be reduced overall, although buildings may cause funnelling effects

• the reduced number of open water bodies: this means less

  evaporation and fewer plants, therefore less transpiration

• the composition of the atmosphere: the blanketing effect of smog, smoke or haze

• the reduction in thermal energy required for evaporation and evapotranspiration: this is due to the surface character, rapid drainage, and generally lower wind speeds

• the reduction of heat diffusion: this is due to changes in airflow patterns as a result of urban surface roughness.

what is the centrifugal movement

movements of people out from the centre of the urban area.