The growing population and increasing urbanization have caused a phenomenon known as urban sprawl in major cities of the world. This issue has imposed much economic and environmental consequences on cities. According to this review, it is necessary to recognize and assess this phenomenon. This study ...
The growing population and increasing urbanization have caused a phenomenon known as urban sprawl in major cities of the world. This issue has imposed much economic and environmental consequences on cities. According to this review, it is necessary to recognize and assess this phenomenon. This study is a theoretical-practical research in terms of objectives and a descriptive-analytical one in nature. Today, landscape metrics and spatial data are used widely throughout the world to measure and evaluate urban sprawl. In the present study, to measure urban sprawl in Urmia, the spatial-temporal data and landscape metrics are used for the first time to measure urban sprawl in Iran. In this regard, satellite images related to the years 1991, 2001, 2011, and 2015 were collected. Then, the data was classified into two categories of constructed and unconstructed lands using artificial neural network. Afterwards, changes were detected by ENVI4.8 software program and the urban sprawl in Urmia was assessed applying landscape metrics (shape index, fractal dimension index, contiguity index, number of patch index, largest patch index) using the Fragstats4.2 software program.
Investigation of shape index indicates the sprawl trend in Urmia. During 1991-2011, this index continuously declined, indicating the reduction of sprawl trend in the Urmia during this period. From 2011 onward, the trend has taken an uptrend that shows the increase of sprawl trend in the city. This points to the irregularly made patches that lead to random growth and unplanned development of urban areas.
Fractal dimension describes the complexity and fragmentation of each patch by perimeter to area ratio. Increased complexity and fragmentation causes increased perimeter and thus increased fractal dimension. Therefore, increased fractal dimension shows an increase in the urban sprawl intensity. During 1991-2011 in Urmia, the intensity of sprawl was declining partially. However, during 2011-2015, the phenomenon of sprawl and developments in suburb areas intensified in the city.
The high value of Contiguity Index means more compaction. This index had a balanced trend during 1991-2011 and maintained its existing compaction. However, during 2011-2015, this index transformed and went through a significant downtrend, showing the tendency for sprawl in the city.
Number of Patches Index intensifies when the extent of sprawl increases. The investigation of this index in the study area indicates the reduction of sprawl area during 1991-2011, so the intensity of sprawl reduced to some extent. But, after this interval, i.e. from 2011-2015, sprawl intensified in Urmia.
The investigation of this index in the study area shows an oscillating trend in a way that the trend reduced during 1991-2001 and, thus, the sprawl intensity in the region reduced. During 2011-2011, the value of this index increased and the studied area tended more intensely toward urban sprawl. Finally, sprawl intensity in Urmia increased significantly during 2011-2015.
The results of the present study show that urban sprawl in Urmia has followed a descending trend during 1991-2011 and an ascending trend ever since.