Theory

• Urban sprawl is the spread of an urban area into the countryside. This is one of the main causes of wildlife habitat loss and causes more air pollution and an urban heat island effect. This also means there is an impact on water quality and quantity with an increased flood risk.
• Population density tends to be high in urban areas and one of the consequences of this is a shortage of accommodation, leading to the presence of large areas of informal and inadequate housing - develop on edge of cities, prone to hazards such as flooding and landslides. (2017 - 900 million, 25% of urban population - 2030 - 1 in 4 in an informal settlement)
• In the UK, the rising demand for accommodation in cities has led to a dramatic increase in both house prices and rental costs (increased 70% between 2010 and 2019 in London), fuelled by in-migration, gentrification and by wealthy investors purchasing properties.
• Financial restraints in lower-income countries can result in a lack of basic services such as water and electricity. Maintenance of infrastructure such as roads, sewers and drainage is also limited, resulting in traffic congestion, polluted watercourses, flooding and the rapid spread of disease.
• Since a high proportion of people who move to cities are relatively young, there is considerable pressure to create sufficient job. Under-employment refers to a situation in which a person is not doing work that makes full use of their skill and abilities, often occuring due to migration.
• The processes of urbanisation and suburbanisation have led to increased traffic in cities across the world, creating more congestion and pollution, damaging human health and wasting billions of pounds in lost productivity.