تحلیل پویش فضایی شهرهای منطقه ای در گذار به کلانشهر؛ مورد مطالعه: شهر رشت (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
شهر در طی حیات خود تحت تأثیر عوامل درونی_بیرونی، در بستر مکان و در گذر زمان دستخوش تغییرات فراوانی قرار گرفته و به رشد و توسعه خود در جهات مختلف شکل و ابعاد بخشیده است. بنابراین، توجه به الگوی رشد و گسترش شهر، پایش تغییرات کاربری و پوشش زمین در شهرهای بزرگ، برای مدیریت رشد و پایداری اکوسیستم شهری امری حیاتی است. بر این اساس، پژوهش حاضر با هدف تحلیل پویش فضایی شهرهای منطقه ای در گذار به کلانشهر(مورد مطالعه: شهر رشت) و با روش توصیفی_تحلیلی انجام شده است. داده های حاصل از پژوهش با روش اسنادی و با استفاده از تصاویر ماهواره ای لندست جمع آوری شده است. برای پردازش داده ها از مدل دیویس، تصاویر ماهواره ای(ایجاد نقشه های کاربری و پوشش اراضی شهر رشت در چهار کلاس) و همچنین کاربست متریک های فضایی در سطح کلاس، با استفاده از نرم افزار FRAGSTATS استفاده شده است. یافته های کیفی پژوهش نشان داد پویش فضایی شهر رشت، پویش فشرده و مبتنی بر گذار سریع بوده است. این پویش، تحت تأثیر عوامل مختلفی همچون نیروها و توان های طبیعی، مؤلفه های سیاسی، سیاست های اقتصادی و طرح های توسعه ای، توسعه زیرساخت ها و نظام ارتباطات، ادغام پدیده های فضایی پیرامونی در محدوده کالبدی شهر، گسترش اسکان غیررسمی و همچنین جریان های مهاجرتی، همواره دستخوش تحول و دگرگونی شده و بازتاب هایی را به دنبال داشته است. از جمله مشخصه های عینی و بازتاب های آن می توان به تغییرات نظام کاربری و پوشش زمین، پراکنده رویی شهری، عدم تعادل در سازمان فضایی شبکه و سلسله مراتب شهری، خدماتی شدن و گسترش بنیادهای اقتصاد شهر اشاره نمود. یافته های کمی پژوهش نیز مؤید افزایش سطوح کلاس کاربری شهری از چهار هزار و 915 هکتار به نُه هزار و 960 هکتار و در مقابل کاهش پوشش کشاورزی از 29 هزار و 504 به 28 هزار و 233 هکتار و آهنگ کاهشی مشابه در پوشش شالیزار و مناطق جنگلی طی سال های 1398-1372 است. همچنین نتایج متریک های فضایی بیانگر افزایش 103 درصدی مناطق شهری و گسیختگی زمین های کشاورزی و شالیزارهاست که آهنگ پرشتاب پویش فضایی شهر به پراکندگی کالبدی را به دنبال دارد.Analysis of the spatial dynamics of regional cities in the process of transition to metropolis: Rasht
Highlights
The trend of spatial dynamics in the city of Rasht, Iran has been intensive and based on rapid transition.
Rasht has experienced many spatial reflections in the process of transition to a metropolis.
Rasht has been influenced by various forces and factors in its transition to a metropolis.
Introduction
It is believed that the city, a living, dynamic entity influenced by internal-external factors through time and space, is subject to change and transformation, and its growth and development are affected by different aspects. Therefore, given the pattern of growth and expansion of the city, continuous monitoring and forecasting of land use changes and land cover in large cities is critical for management of the growth and sustainability of the urban ecosystem. Accordingly, the present study aimed to analyze the spatial dynamics of regional cities in the process of transition to a metropolis, focusing on the city of Rasht, Iran.
Theoretical Framework
Urban development is a long-term process of interaction between human activities and land. During this process, numerous changes may be brought about from various fields, such as ones in land use conditions, road network upgrades, population migration, and industrial structure optimization. Since the needs of societies and human groups are constantly changing and transforming due to their inherent dynamics, the built spaces are also subject to gradual change as spatial systems. Therefore, urban dynamics are representations of changes in urban spatial structures over time, which embody a myriad of processes at work in cities on different but often interlocking time scales ranging from life cycle effects in buildings and populations to movements over space and time as reflected in spatial interactions. City formation and development have occurred in different ways in different regions of the world and at different times, driven by diverse political, economic, social, and cultural processes )Bruns-Berentelg et al., 2020: 2( and technological changes (Pacione, 2005). Technological innovations have allowed flows of information, knowledge, and money to circulate across the world quickly, helping to intensify the ongoing, but previously slow, process of compression between time and space (Harvey, 1989). This has supported the processes of economic decentralization and globalization, enabling the emergence of new geographies where physical and political boundaries are not as important as before (Sassen, 1991; Castells, 1997). These shifts have contested usual concepts such as scale and territoriality, resulting in new forms of spatiality )Borges, 2010). According to Berg et al. (1982), cities evolve in a clearly defined sequence of stages that can be conceptualized in a model of urban development based upon population changes in urban regions as a whole and upon shifts of population within these regions )Clark, 2003: 61(.
Methodology
The research method was descriptive-analytical. Therefore, it sought to answer the following questions. What is the process of the spatial dynamics of Rasht in the transition to a metropolis? What are the forces and spatial reflections of this city’s drive to join millions of metropolises? In order to answer the research questions, the research data were collected using the documentary method and Landsat satellite images. The main data were extracted from US Geological Survey (USGS), taking into account MSS, TM5, and OLI sensor images of the Landsat satellite with a resolution of 60 by 30 meters from 1993, 2003, 2011, and 2019 (June, July, and August without clouds). Land use maps were generated in the four uses of urban and built-up areas, water and paddy areas, forests and agricultural lands, and gardens. In this research, the cycle and spatial dynamics of Rasht were studied, and demographic information was collected from statistics, censuses, and the website of the Statistics Center of Iran using historical data and the Davis model. To investigate the trend of land use change (1993-2019), spatial metrics were used through preparation of a time series of land use maps and land cover in Rasht and measurement of its urban sprawl.
Results and Discussion
The findings demonstrated that the trend of spatial dynamics in Rasht has been intensive and based on rapid transition. Unlike what the general model of urban life cycle stated, this city has experienced population and land use and cover instability in the growth stage, like other large cities. These dynamics are constantly evolving and exhibit repercussions and consequences under the influence of various factors such as natural forces and capabilities, political components, economic policies and development plans, infrastructure and communication system developments, peripheral spatial phenomenon integrations within the physical boundaries of the city, informal settlement expansions, and immigration flows. As far as the objective characteristics and reflections are concerned, one can point out the changes in the land use system and land cover, urban sprawl, imbalance in the spatial organization of the network and urban hierarchy, service-rendering, and expansion of the city’s economy foundations. The outcomes of the above reflections are evident in the rise in urban land use levels and disastrous effects of land and cover resource instability, the increase in the growth of urban areas and vulnerability and rupture of agricultural lands and paddy fields, the gaps in the urban network, and the ever-increasing service-rendering, political-administrative, and physical-spatial development of Rasht. Overall, the results on the changes in land use and land cover confirmed the rise in urban land use levels from 4915 hectares in 1993 to 9960 hectares in 2019. Along with the growth of land use in urban areas, agricultural land coverage has experienced a declining trend in the same period. The results on the spatial metrics also demonstrated that urban areas have increasingly grown, and numerous urban plots have been developed. Concurrently, agricultural lands and paddy fields have lost their spatial cohesion and integrity and have been disintegrated into numerous plots, which implies the fast-paced urban spatial dynamics into physical dispersion.
Conclusion
The city of Rasht is in the process of transition to a metropolis and has undergone fundamental changes in its spatial-physical boundaries along with the instability of land cover resources, the disastrous consequences of which are also the main concern about the city and the urban ecosystem today. Thus, spatial urban management through short-term land cover transformation, on one hand, and infill development policy strategies, i.e. redevelopment and new development, on the other hand, are very important to stabilize growth and slow down transition into a metropolitan area.
Acknowledgment
This article is derived from the doctorate thesis of the first author with the guidance of the second author and the advice of the third author who defended the thesis in September 2020.
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