An Exploration of the Relationship between Illegal Land Use Change and Spatial Structure of Tehran, Using Spatial Regression Analysis

Illegal land use change or unauthorized use of buildings is one of the major building contraventions in Tehran reported numerously to the Tehran municipality during two recent decades. The decisions which have been adopted by the municipality that is responsible for construction and building control through the legal boundaries of the city, and other urban authorities who are responsible for the control and direction of urban development, have not been successful in alleviating Tehran’s building contraventions and even have led to more number of building contraventions and have become an intolerable matter for most of developers. The important role of urban land use policies and proper execution of urban land use regulations in the order and balance of urban development make the prevention of such contraventions necessary. In this paper, it has been presumed that the spatial distribution of building contraventions through Tehran is related to the social, economical, physical structure of the city and distribution of the different land uses in the city. Evaluating of the presumption as one of the possible solutions for decreasing land use contraventions in Tehran was addressed through spatial regression, which is a kind of spatial analysis. In other words, understanding the factors affecting the occurrence of building contraventions will help planners to recognize building contravention opportunities and to use such information to increase the efficiency of urban plans, urban guidelines and policies they present. According to the spatial distribution of the level of land use contraventions (the contraventions reported to “Article 100 Commission” of Tehran municipality as the legal authority for investigating the building contraventions), such contraventions have been mostly concentrated in central districts and two marginal districts located in northeastern and southeastern of Tehran. In order to find the relationship between indicators describing Tehran’s structure including social indicators (population density, average floor area of residential units, percentage of ownership, percentage of rental units, persons per household), economical indicators (average building price and rental price, household income, car ownership ratio), physical indicators (average floor, average FAR, average area of land parcels, percentage of durable building, percentage of non-resistant building) and land use distribution indicators (commercial area, transport network area, official area, green space area, residential area) and the level of land use contraventions reported to “Article 100 Commission” of Tehran municipality, spatial regression analysis was applied for the Municipality Districts No. 1 to No. 20. As the result, the total level of land use contraventions (area of the illegal land use change) in the districts was correlated with the average floor area of residential units in the districts, land and building price, car ownership ratio, the average area of land parcels, floor ratio and the total area devoted to the official land use at 99% and 95% confidence intervals. In other words, land use contraventions have mostly occurred in the districts with more average floor area of residential units, higher floor area ratio, larger size of land parcels, less rental units and more areas devoted to official land use.