پویش جمعیتی و الگوهای پوشش زمین در منطقه کلان‌شهری اصفهان

ABSTRACT
The rapid growth of the urban population and its increasing concentration in metropolitan areas is one of the most obvious developments in the settlements of contemporary Iran. Spatio-temporal population movements have led to complex changes in land cover patterns. This article aims to investigate and analyze the spatial-temporal changes in the urban population and the resulting land cover patterns in the last few decades in the metropolitan area of Isfahan. The research method in this research is descriptive-analytical, and by using the analysis of census data and statistics of urban blocks, as well as the method of classification of Landsat satellite images, it has been done. The findings of the research show that during recent decades, the absolute increase of the urban population has reached the area of 35 km to the area of 25 km of Isfahan city. The results show that the spatial-temporal movement of the urban population in the Isfahan metropolitan area is in the stage of centralization and extensive development. According to the spatio-temporal movement of the urban population, the land cover pattern has also undergone extensive changes. The most important pattern of urban growth resulting from demographic changes in the metropolitan area of Isfahan indicates that the semi-centralized pattern of this region in the 1981s turned into a centralized pattern and was pushed in the 2011s.
Extended Abstract
Introduction
The rapid growth campaign around Isfahan took various forms, such as the expansion of surrounding cities, the transformation of villages into cities, the destruction of some villages, the creation of new cities, and the development of countless industrial towns. As a result of these developments, firstly, the urban centers around Isfahan expanded greatly, and secondly, with the extensive development of the extra-urban communication network, the economic, social, and physical-spatial relations between Isfahan and the neighboring cities entered a new stage in which finally led to the formation of the metropolitan area of Isfahan.
 
Methodology
The data for the study of population changes in Isfahan metropolitan area are the data of the general population and housing census of Iran, which was collected from 1956 to 2016 on a ten-year basis. The present research method is based on the developmental-applicative goal and descriptive-analytical methodology based on library studies and field investigations. This research aims to investigate the spatial-temporal developments of population growth and urban development in the metropolitan area of Isfahan from 1986 in a period of thirty years to 2016. Land cover maps have been produced using TM and ETM + satellite images in 1986 and 2016, and ENVI software has been used for pre-processing, processing, and subsequent calculations. After classifying the images into four main classes, including built-up land, barren land, vegetation, and water, a visual method was used to improve the classification results. The results showed that the overall accuracy of classification results of satellite images in 1986 and 2016 is 88% and 91%, respectively.
 
Results and discussion
The investigation of spatial-temporal patterns of land cover in Isfahan metropolitan area shows that in 1986, built-up lands with an area of about 130 square kilometers (13000 hectares) covered 0.42% of the area. The main focus of the lands built in 1986 was in the metropolis of Isfahan. In 2016, with the passing of 30 years, considerable changes are taking place in the metropolitan area of Isfahan. The built-up area has increased significantly to more than 617 square kilometers, which is 2.01% of the Isfahan metropolitan area, and compared to 2016, it has experienced an almost 5-fold growth. The absolute increase of the built lands in this period was 486.28 thousand square kilometers. This is while the area of Isfahan city was 76 square kilometers in 1986, which reached 175 square kilometers in 2016 and grew 2.5 times. The most significant number of changes in the metropolis of Isfahan and the surrounding cities have mostly occurred in continuous and radial growth in the axis of the western, northern, southern, and southwestern cities.
 
Conclusion
The results of spatial analysis based on the standard deviation ellipse for the absolute changes in the urban population and the growth rate of the urban population in the metropolitan area of Isfahan in the period from 1956 to 2016 show the formation of centralized, semi-centralized, and decentralized population patterns. Therefore, in 1956, about 79 percent of the region's population was concentrated in a radius of 21 kilometers from the center of Isfahan city. With time, the radius of concentration of the population in the metropolitan area of Isfahan has increased so that in 1986, about 92% of the population of the region was scattered in a wider radius towards the west of the region. This situation shows the transition from a semi-centralized pattern to a decentralized pattern in the spatial distribution of the region's urban population. This is while in 2016, the radius of the population concentration area within 25 km of Isfahan city was formed again, and 76% of the population concentration of the region was created in a narrower radius than the previous period. This situation shows the transition from the decentralized model to the centralized model and the return of concentration in the spatial distribution of the region's urban population in 2016. Spatial-temporal developments of urban population growth rate show a different situation with absolute population changes, so the radius range of the population growth rate of each period is wider than the previous period and shows a higher population concentration. In the 1951s, the pattern of urban growth in the metropolitan area of Isfahan was concentrated, and in addition to Isfahan, 4 cities of Khomeini Shahr, Najaf Abad, Zarin Shahr, and Shahreza had significant populations. In the 1981s, the pattern of urban growth in the Isfahan metropolitan area continued as semi-concentrated growth, and in addition to the formation of new cities, some cities in the region experienced the highest population growth rates compared to previous and subsequent periods. In the 2011s, the pattern of urban growth in the metropolitan area of Isfahan experienced concentrated growth, and in this era, the intensity and speed of the formation of built-up areas were accompanied by a compact, continuous, and radial development, and Isfahan city overcomes itself with more dominance and development. The main factors shaping this centralized urban spatial pattern should be summarized in the excessive development of the province's industrial sector, the location of industrial towns, and the development of communication routes in the region. The formation of intense migration waves within the province and city is another factor in expanding the regional centralization process. Changes in land cover in the recent period show that more than 58 percent of the built-up lands in the region belonged to the Isfahan metropolis and its surrounding area of influence. In this period, the scope of expanding industries extends to 10 km of Isfahan city. The initial concentration of urban areas, following the establishment of major job centers in the western and northern sectors of the region, has gradually been accompanied by the concentration of urban areas within 20 to 40 kilometers of Isfahan city.
 
Funding
There is no funding support.
 
 
Authors’ Contribution
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
 We are grateful to all the scientific consultants of this paper.