As urban populations increase, the tendency is for the land area devoted to urbanisation to increase as well (rather than for the city to become denser). Although this process has been strongest in the US, because of the predominance of single-household detached housing and the ubiquity of the automobile, the spread of urban areas into adjacent green spaces has also been a feature in Europe, where cities have become less compact than they used to be.
Urban sprawl has implications from different perspectives:
- the environment: sealing surfaces, emissions caused by transport, ecosystem fragmentation
- the social structure of the city: segregation, changes in lifestyle and the neglect of town centres
- the economic structure: distributed production, changes in land prices and issues of scale.
Urban sprawl can be controlled or limited by regulatory measures (e.g. spatial land use planning, restrictions on specific land use), economic intervention (e.g. trading in building permits) and institutional change and management (e.g. special agencies for urban revitalisation).
Examples of measures to limit urban sprawl are encouraging building on brownfield land (which may lead to projects aimed at giving new environmental value to derelict green areas and fringe areas), minimising sealed spaces between buildings, renovating unused buildings, dividing large building plots to allow for the construction of new buildings on the plot, promoting vertical development and improving the quality of land use (e.g. converting unused street areas into building plots).
To apply these types of measures, the administration bodies can adopt GIS tools that provide all the necessary detailed land use information to assist planners and decision makers to regulate and/or guide the development throughout the urban management process.
Another practical technique that can support the control of urban sprawl is to properly regulate the growing difference between the demand and the supply of the urban services.