Studying the factors affecting urban dispersion in mashhad metropolis

Abstract

In recent decades, urban population in the world, especially in southern countries, has exceeded rural population that has brought about urban land expansion followed by dispersion phenomenon, the result of which has created problems in environmental, economic, social, and physical aspects including increased air pollution, potential deterioration within the city, and destruction of farms and open spaces. The aim of this study is to investigate the roots of dispersion in Mashhad metropolis in order to identify solutions to control this problem. The tools used in this research were GIS software for mapping, quantitative methods of Holdren Model, urban primacy index, and area to population growth rate for review and analysis, and at first by examining area to population growth rate, Mashhad- developmental process map, Holdren model, and gross population-density dispersion model of this city was shown.Then the roots of dispersion including market failure (checking the price of land), technology, natural population-growth process, and migration were analyzed. To study the dispersion in Mashhad metropolis, Holdren model was used, according to which only 34% of dispersion is population growth, and 66% of urban growth is related to horizontal growth. This is indicative of the dispersion in Mashhad metropolis, and the most important reasons are low price of housing in the suburb, ignoring social costs arising from it, increasing percentage of car ownership, gradual population growth in Mashhad due to political priority, and the concentration of facilities in it that are the reason of increase in immigration to this metropolis. To deal with this phenomenon dispersion, it is proposed that patterns of sustainable development such as transportbased development and compact city are used. Key words : urban dispersion, technology, roots of Mashhad dispersion, the price of land, immigration