Urban Sprawl And Other Effects Of Urbanization

Shifting population from rural to urban area is called urbanization and during six last decades, urbanization has proceeded rapidly. In 2017, 55 % of the world’s population lived in urban areas. The urbanization will increase to more than 66% in 2050; while in 1950, more than two-thirds of people worldwide lived in rural areas (fig.1).

Suburbanization refers to shifting the residential area to outward. Suburban sprawl demonstrates a balance between the forces that are pushing people together in cities and those pushing them out. Some researches show that suburbanization has gone so far to form new points of concentration outside the downtown (Sridhar, K. S., 2007). The urban growth often occurs by expanding around the cities peripheries. However, the cities sometimes get bigger by increasing their central densities that leads to form a compact city (also urban densification (Varma G., 2016) or urban intensification) by concentrating growth in compact walkable urban centers to avoid sprawl.

There are different factors affecting on the urban growth as economic, environmental, health and social effects. These factors make the cities to grow by different patterns. As illustrated in figure 2, five different pattern could be considered as the urban sprawl patterns (Galster et al., 2001). The urban growth management strategies (GMS) (Pollock P., 2008) is the method, which is used to manage growth rate of the cities. The important factors of the GMS can be consider as

• The amount, type, extent, rate, and quality of urban development,
• Protection of natural spaces, sufficient and affordable housing, delivery of utilities, preservation of buildings and places of historical value, and sufficient places for the conduct of business.
• Impact fees (e.g. transportation improvements, new parks, and expansion of schools
• Application of zoning to reduce the cost of service delivery such as fire protection and emergency medical response services
• Preventing suburban densities from affecting a large area
• Urbanization and urban growth could make irreversible changes. These changes can impress on biodiversity, ecosystems and urban climate, transform landscapes and degrade agricultural and natural areas.

Sustainable urban planning requires reliable land change models. Migration, communication, management of urban heritage, the urban planning projects and implementation or simulation of noise, pollution, climate change, flooding and urban sprawl are some of the purposes that tend the decision makers to work on land use models.

Urban expansion models can be considered as two main types of economic models based on the interactive use of land-transportation and spatial models, specifically the occupation change models and land use. Any of them can be classified as process-based or pattern-based model.

There are various urban growth techniques. Among them the cellular automata modeling, agent-based modeling, artificial neural network modeling and fractal modeling are the most used urban growth models and land use changes in the last two decades.

In this paper, some applications of these models are discussed. However, the micro simulation such as the agent-based and cellular automata simulation techniques offer greater potential for representing and simulating the complexity of the dynamic process, due to the increasing of computational power and greater availability of the spatial data (Dietzel and Clarke, 2004).

This paper is organized as follows; first, fractal modeling will be described in section 2. The artificial neural network modeling will be presented in section 3. In Section 4, the agent-based modeling will be defined. In section 5, the cellular automata modeling will be represented. The paper will be concluded in section 6.