İstanbul'da şehirsel saçaklanmanin ölçülmesi.

Sprawling urban development is one of the major concerns in terms of sustainable urban development. Critics of sprawl argue that urban expansion invade the agricultural land, leading to a loss of amenity benefits from open space. In addition, growth at the urban fringe is thought to depress the incentive for redevelopment of land closer to city centers, leading to decay of city centers. Under free-market conditions the decisions of individuals minimize costs and maximize profit. This is mostly in favour of conversion of rural land leading to sprawling urban development because it is easier and more profitable due to lower land values. In response to concerns about sprawl, compact development strategies have been proposed in order to alleviate the market failures and promote sustainable development. Therefore, urban planners require information related to the rate of growth, pattern and extent of sprawl to provide basic measurements to define sprawl characteristics. Measuring urban sprawl is a controversial topic among scholars who investigate the urban landscape. There have been many attempts to measure sprawl by developing quantifiable indicators. Density is considered as one of the essential components of measuring sprawl. Since density is a very complex concept and its measures vary in several ways, it is important to determine how the relationship between density and sprawl should be evaluated. The density gradient is an alternative approach to quantifying density instead of using the number of people or dwelling units per given area. The idea of a density gradient is the percentage change in density for a small change in distance from an urban center, or the density gradient of sprawl. It can be argued that the density gradient model, which generalizes urban form as monocentric, is a good fit in explaining urban dynamism as cities grow and economies develop. Using measurable indicators, researchers created a sprawl index based on factors that can be analyzed. Recently, scholars have also identified measurable characteristics of sprawl and proposed specific indicators of sprawl to characterize patterns of urban growth and land use. The other attempts involve using certain spatial simulation techniques to measure urban form both in theoretical simulations and while using empirical data. The aim of this paper is to provide a sprawl measurement methodology that contributes to the understanding of sprawl dynamics of Istanbul. In this paper, a sprawl index was calculated to measure urban sprawl in Istanbul. The information that was used in the sprawl index was assembled for each of 787 neighborhoods of Istanbul. For each neighborhood level, the built up areas of neighborhoods have been taken as the statistical units for the calculation of the sprawl index. 18 variables related to built-up areas were collected and entered into database. Using factor analysis 18 indicators were explained by three components (density, mix-use and accessibility) and then each neighborhood received density score, mix-use score and accessibility score. Since 'density' and 'accessibility' have an inverse effect in the context of urban sprawl measurement, the accessibility factor is considered as a negative component, while density and mix-use were considered as positive component in the calculation of sprawl index. Consequently, using sprawl score, Istanbul is divided into five zones ranging from the most sprawled to the most compact. The results demonstrate that the spatial development pattern of Istanbul exhibits urban sprawl characteristics. Current planning approach alone is not effective to reduce sprawl without setting certain spatial strategies by which development activity is restricted or additional requirements for new development are imposed in certain areas. This brings the compact development strategies to planners' attention as a way to control urban sprawl. For further research, it should be investigated if uncontrolled urban sprawl might feasibly be shifted from the areas where it now seems likely to occur into other areas closer to the center of the metropolitan areas. [ABSTRACT FROM AUTHOR]