عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Metropolitan regions are one of the emerging phenomena of the 20th century which have turned to a dominant pattern of urbanization at the beginning of third millennium. Although the metropolitanization phenomenon has been formed as a result of economic and spatial rules and interactions at the global level, and continue their evolution process, but lack of adequate research and strategic studies at the metropolitan area scale has resulted in non-formation of required institutions at the level of metropolitan areas. These Metropolitan Regions which have experienced transformation in role and functions, evolution in form and structure and changes in the meaning and concept, due to various forces and factors, have followed a certain process and mechanism in formation, evolution and transformation temporally and spatially, and in both the developed and the developing countries.
It was hoped that the introduction and implementation of decentralization and rural development policies would result in decreasing the social, economic and spatial inequalities in developing countries. After two decades, however, the cities, specially the metropolises have been turned into engines of growth and economic development. The globalization phenomenon and the competition between large metropolises, on the other hand has resulted in introduction of policies that emphasize the roles and status of metropolitan areas in their national urban system. Therefore, the accelerated expansion and the management system of these metropolitan areas need a special attention.
The main objective of this study is to analyze the formation, evolution and transformation of Tehran Metropolitan Region. To achieve this objective, the concept of metropolitanization and its processes have been discussed; theories and models related to the process and stages of growth and expansion of metropolitan areas have been studied. In the section of the paper, the formation process and the evolution of spatial organization of metropolitan regions has been discussed. Suburbanization, the process of changes in urbanization and the formation of the metropolitan regions and also the conclusion are presented at the latter parts of the paper.
The present study shows that the formation, evolution and transformation of metropolitan regions are an outcome of simultaneous interaction of two effective processes named concentration and de-concentration. These two processes have led to a dynamic organization of the metropolises and metropolitan regions that can be named Continuity and Discontinuity. In the concentration process, all high-order and global functions and services have basically concentrated in central business districts of the metropolitan areas. In contrast, according to the de-concentration process, a given part of activities and their related services and population will move into the other urban centers of the metropolitan region.
In fact the metropolitanization phenomenon is a result of the processes that have evolved during the evolution and transformation period. These metropolitan regions in the process of expansion and concentration, by increasing the agglomeration costs push some of their activities and functions to surrounding areas and a result create large fringe areas. In this process the search for housing and employment opportunities in these fringe areas are one of the most important factors in the formation and expansion of these metropolitan areas. The results of this study also shows that the development and expansion of cities and metropolitan areas in the future would follow a definite and identified concept which could be called "de-concentrated concentration".