تبیین سیاست ‏های مستقیم دولت در زمین شهری بر الگوهای رشد پیراشهری کلان‏ شهر (مطالعه موردی: شهرهای شرق تهران)

الگوی رشد شهر، ازآنجاکه با یکی از محدودترین منابع در دسترس انسان یعنی زمین سروکار دارد، از موضوعات مهم در برنامه‏ریزی شهری است. بررسی مراحل رشد و توسعه کالبدی کلان‏شهرهای جهان از گذشته تا به امروز نشان می‏دهد که سیاست‏های مستقیم وغیرمستقیم دولت درتغییرات الگوهای رشد،به‏ویژه در مناطق کلان‏شهری،بسیار مهم بوده واین سیاست‏ها در سایر تغییرات از جمله تغییرات تکنولوژیک موثر باعث رشد فیزیکی سریع شهرها و تبدیل شهرهای فشرده به شهرهای گسترده شده است. مطالعه الگوهای رشد کلان‏شهری ناشی از سیاست‏های دولتی در بسیاری از کشورهای درحال‏توسعه و توسعه‏یافته با توجه به شرایط خاص اقتصادی اجتماعی کشورها نشان می‏دهد که مدیریت و برنامه‏ریزی علمی باید براساس درک مناسبی از فرایندهای فضایی زمانی رشد شهری باشد. کلان‏شهر تهران،به‏عنوان مهم‏ترین شهر کشور،از شروع تحولات اقتصادی–اجتماعی سده حاضر سکونتگاه‏های پیرامون خود را تحت تاثیر قرار داد و این سکونتگاه‏ها به صور مختلف از تغییرات فیزیکی اقتصادی و اجتماعی موجود در تهران تاثیر پذیرفتند؛ این امر سبب شد الگوهای رشد متفاوت متاثر از سیاست‏های زمین شهری در پیرامون کلان‏شهر تهران شکل یابد. این مقاله با هدف تبیین الگوهای رشد شهرهای پیرامون کلان‏شهر تهران با تاکید بر سیاست‏های مستقیم دولت بر زمین شهری تدوین شده است. تحقیق حاضر از نوع توصیفی تحلیلی استو شیوه جمع‏آوری اطلاعات مطالعات کتابخانه‏ای است. در این مقاله به بررسی سیاست‏های مستقیم دولت در دو شهرشرقی کلان‏شهر یعنی رودهن و پردیس پرداخته‏ شده و سپس با استفاده از مدل سلول‏های خودکار نوع تغییرات در هر شهر ناشی از سیاست‏ها ترسیم شده و همچنین رشد آتی این شهرها الگوسازی شده است. نتایج حاصل نشان داد فرایندها و الگوهای فضایی زمانی رشد شهری در مناطق کلان‏شهری شرق تهران بازنمایی فضایی ساختارها و سازوکارهای اجتماعی اقتصادی و سیاسی حاکم بر جامعه بوده واین سیاست‏ها در شکل‏دهی الگوهای متفاوت رشد در شهرهای پیرامون نقش اساسی داشته است.

explaining impacts of state land use policies on physical growth of metropolitan suburbs (case study: pardis and rudehen)

introductionurban physical growth and its pattern is one of the key issues in the field of urban planning because of its relation to the management of land as a scarce resource in cities. analysis of urban physical expansion in metropolitan regions around the world shows the important direct and indirect impacts s of state policies on the city expansion. with regard to the city expansion, two different patterns are recognizable, including sprawl and compact (or continuous) expansion. state land use policies, along with rapid transformations in technology (i.e. transportation and information) have stimulated urban sprawl significantly in these regions. to explain the impacts s of state land use policies on metropolitan physical growth entails a spatiotemporal framework of analysis. in this article, we are to evaluate these impacts s in the tehran metropolitan region. the city of tehran as the centre of the region has experienced significant sociopolitical transformation over the past century, resulting in different social and economic changes in its surrounding settlements. these intensifying centresurrounding relationships have led to shaping a particular pattern of physical expansion of cities in the region. this article aims to explain the pattern of city physical expansion in the surrounding area in relation to state urban land use policies.methodologyas noted above, this article as a descriptiveanalytical study attempts to analyze the impact of state urban land policies on the eastern cities of the tehran metropolitan region, including rudehen and pardis. to do this, it analyses legal urban land use regulations and satellite data to explain, predict and simulate how these cities expand spatially in the region. discussionrapid urbanization is an influential force to change the face of the earth. then, it is necessary to explore and manage the spatial pattern of urbanization, especially in metropolitan regions. in recent years, there is an increasing interest to investigate land use change, urban expansion and related socioeconomic processes in the tehran metropolitan region. the city of tehran has experienced a variety of socioeconomic changes after the modernization period in iran. especially, after the 1970s when continuous expansion of tehran has replaced with sprawl, sociospatial landscape of its surrounding cities such as rudehen and pardis has also changed significantly. diffusion of growth from the centre, i.e. from tehran to its periphery, i.e. to its surrounding cities took place without any integrated, comprehensive regional planning. during 19661996, there were only two cities, including tehran and karaj, where the processes of urban land use and urban expansion were being managed through master plan. this article argues that while the region was experiencing rapid process of urbanization and physical expansion during this period, there was no will to manage and plan it regionally. the physical growth of both rudehen and pardis is a function of macro policies of urban land use in the region. pardis as a new town was established by state regulations to facilitate decentralization of population from the city of tehran to its surrounding region. pardis is, in fact, the embodiment of maximum intervention of the state into the production of the metropolitan region to the extent that the whole of urban planning process, from designing to selling, is essentially led by the state. the state is the owner of the city, and then it facilitates its physical expansion and growth because of economic benefits from land business. in the case of rudehen, two different forces are working to stimulate urban physical expansion: first, lowincome immigrants who are not able to reside in the city of tehran because of highvalue rent decide to reside in rudehen; second, highincome immigrants who are seeking natural landscapes for pleasure find it a suitable place. the former creates the spaces of slums while the latter spaces of second homes. in general, we can interpret growth of the two cities as a reaction to socioeconomic forces of the city of tehran itself. rudehen is expanded at both sides of tehran road. in the case of rudehen, its growth follows sprawl expansion, and tehran road acts as a local force to control the pattern of urban sprawl. in other words, the urban sprawl decreases with increase in distance from the road. the northern part of the city has experienced more expansion than the southern part. with respect to pardis, three different stages of physical growth are recognizable. first, the city continued to expand in a compact pattern of expansion until 1987. during this stage, pardis, like rudehen, expanded along tehran road in a linear pattern. at the second stage, i.e. from 1987 to 2003, the expansion of the city gradually shifted towards sprawl pattern. tehran road conditions this kind of expansion too. the city, at the third stage, has expanded along two main axes. one runs along the southnorth corridor, the other along eastwest corridor. the former axis shows the compact pattern of expansion while the latter axis exhibits sprawl. analysis of data showed that in both cities, the dominant geographical orientation of expansion is similar. in other words, the dominant geographical orientation of the expansion is toward the west, i.e. toward the city of tehran. furthermore, the western part of the two cities is more compact than their eastern part, indicating the powerful gravity of the city of tehran on the physical growth of its surrounding cities. conclusionresults showed that the physical growth of cities (i.e. rudehen and pardis) in the tehran metropolitan region follows a different and complicated pattern in comparison with premodern urbanization of the region. this article argues that the spatiotemporal processes and patterns of peripheral urban expansion are a spatial reaction to dominant socioeconomic structures and relations of the city of tehran itself. analysis of spatial and temporal trends of urban physical growth enables planners to prevent or reduce urban sprawl in the region. for this, strategies related to urban land use should be modified to shift from maximum intervention of the state to its minimum intervention. this entails that urban growth strategies should encourage public participation in the process of urban land use planning