What is meant by urban? There is no single definition or set of exact criteria used to identify 'urban' areas. In France, any area which has a population of over 2000 is considered urban, while in India it's over 5000. Other criteria such as the number of workers not employed in agriculture, or population density are used to determine whether a particular area is urban or not.The lack of a precise definition means that people are often cautious when discussing urban areas, and are often more general in their comments.
What functions are present in urban areas? A function simply means an activity, and compared to rural areas, there is a large difference in both quantity and variety of functions carried out in urban areas which serve the urban area's inhabitants as well as the people living in the surrounding area.Depending on the importance of the city, these functions can have national and international links. The main functions found in most urban areas will be residential, economic (such as manufacturing), commercial and retail, political and administrative and public-service related functions such as schools and hospitals, transport infrastructure and recreational. Different urban areas will provide different combinations of these functions, based on the needs of the population. We can see where this is happening by looking at land-use patterns. For example, tourism is a very prominent function in Bath and Blackpool, while manufacturing is important in the city of Belo Horizonte, Brazil.
How do economic processes affect urban land use? Where there is a free market for land, whoever offers the most money will usually end up acquiring the land. Central locations always attract the highest bids from the most wealthy bidders in the market, as it's the best position to own in an urban area, because it offers the best access to potential customers. This area becomes the city centre and is generally the hub of that particular urban area. Transport infrastructure tends to be the best in the centre and the city builds up around it, normally fairly evenly. The city centre becomes the most wealthy area of the city, and acquires specialist services, and prestige. Residential land use cannot compete financially with commercial land use, and so the residential areas are usually build further away from the centre. Many cities have grown as housing has out-bid agriculture for land on the outskirts of the urban area (Figure 1). The land value surface can be identified as a three-dimensional aspect of urban areas. It shows the general decline in land values with distance from the Central Business District (CBD) and also shows the subordinate peaks of land value. These are usually at places where general access is improved, such as at the intersection of some main roads in the suburbs of an urban area. Clusters of shops and small groups of offices can be found at locations such as this. In residential areas there are obvious differences when comparing the cost of housing, depending on a variety of factors. A general trend is that housing costs increase the further away they are from the CBD. This often leads to cheaper houses being built on the more expensive land closer to the centre, with the opposite occurring as you move further away from the centre. The reason for this is usually to do with the density at which the houses are built. The inner areas are often built at much higher levels of density, with the houses further away from the centre often being less dense. There are exceptions, where high-cost locations near the centre attract some high-value housing. For example, in London, areas like Kensington and Chelsea retain high-value residential areas because these neighbourhoods benefit from being close to the high-order functions of government and the City of London. Other areas, such as St Peter's Wharf, Sunderland, and LA Boca, in Buenos Aries, have been gentrified, which means that an influx of higher social-status groups have bought run-down properties and renovated them within the inner area of the city. The opposite can also apply, meaning that some lower value areas can be found on the outskirts of cities, usually in the form of local authority estates, such as Seacroft in Leeds.
Figure 1 - Bid rent model
Unreported World - The city with too many people This programme focuses on the city of Manila, Philippines. It is known to suffer from overcrowding, and this programme explores the causes and effects of this geographical issue.
Managing urban change