Urban Expansion (HL IB ESS OLD COURSE - IGNORE)
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
Suburbanisation & Urban Sprawl
What is suburbanisation?
Suburbanisation is the process where people move from the dense central parts of cities (urban areas) to the less dense, peripheral areas (suburbs)
It involves the expansion of cities into nearby rural or undeveloped areas, creating lower-density residential areas
People often move to the suburbs in search of larger homes, green spaces, and better living conditions away from the congested city centre
What is urban sprawl?
Urban sprawl refers to the uncontrolled expansion of urban areas into surrounding rural land, creating spread-out developments
Urban sprawl is closely related to suburbanisation, as lower-density housing and commercial developments require more land, stretching the boundaries of the city
Sprawl often leads to longer commutes, greater car dependency, and increased demand for infrastructure such as roads and services
Causes of suburbanisation
Desire for more space:
People move to the suburbs for larger homes and gardens
Suburban areas often have more green spaces and parks than city centres
Improved transport links:
Advances in public transport and the widespread use of cars have made commuting from the suburbs to city centres easier
Suburban residents can travel to the city for work, shopping, and leisure
Perception of better quality of life:
Suburbs are often seen as safer, quieter, and better for raising families compared to crowded city centres
Suburban areas may offer better schools and lower crime rates
Rising urban costs:
High costs of housing and living expenses in city centres push people to move to the more affordable suburbs
Traffic congestion and overcrowding in city centres:
City centres are often very busy with people and congested with traffic, making commuting and living in the urban core more difficult
Environmental Impacts of Urban Expansion
Loss of agricultural land and natural ecosystems
Loss of farmland:
As cities expand, they often take over land previously used for agriculture
This reduces the amount of land available for growing food
For example, in Beijing, China, rapid urbanisation has consumed large areas of farmland, leading to concerns about food security
Deforestation:
Urban expansion can lead to the clearing of forests to make way for housing, roads, and businesses
This destroys natural habitats and reduces biodiversity
For example, the growth of São Paulo, Brazil, has resulted in the destruction of parts of the Amazon rainforest
Loss of wetlands and ecosystems:
Expanding urban areas often fill in wetlands, rivers, and lakes, reducing habitats for wildlife and affecting water systems
For example, in Florida, USA, urban sprawl has reduced the size of the Everglades, an important wetland ecosystem
Changes to water quality and river flows
Water pollution:
Increased construction and industrial activities near cities can cause pollution to rivers, lakes, and groundwater
Chemicals from factories, waste from homes, and run-off from roads can contaminate water supplies
For example, the Ganges River in India suffers from severe pollution due to urban growth and industrial waste from several major cities
Altered river flows:
Expanding cities often build dams, divert rivers, or drain wetlands, which changes the natural flow of water
This can lead to flooding or drought in nearby areas
For example, in Las Vegas, USA, the city’s rapid growth has strained the Colorado River, leading to water shortages and environmental issues
Air pollution
Increased traffic and industry:
As cities grow, they generate more air pollution from cars, trucks, and factories
This increases levels of harmful gases like carbon dioxide and nitrogen oxides, contributing to climate change and health problems
For example, Mexico City is known for having high levels of smog and poor air quality due to urban expansion and traffic congestion
Heat islands:
Urban expansion often creates urban heat islands
This is where cities become significantly warmer than surrounding rural areas
This happens because buildings, roads, and other urban surfaces absorb and retain more heat than natural landscapes like forests or grasslands
Air conditioners, vehicles, and industrial activities release additional heat into the environment
Loss of biodiversity
Habitat destruction:
Urban expansion can destroy the natural habitats of plants and animals, leading to a reduction in biodiversity
This puts species at risk of extinction
Examiner Tips and Tricks
Always try to make connections between environmental impacts. For example, urban expansion can lead to deforestation, which contributes to air pollution and loss of biodiversity.
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