Analysis of the Effects of Urban Sprawl on Social Vulnerability (Case Study: Qazvin City Districts)

Iran is a country prone to earthquakes in which so many cities have experienced earthquakes in far and near past. Although there is a high potential for earthquakes to be destructive, the level of losses and damages of them is not solely dependent on the magnitude and the location of the earthquake, or physical aspects of buildings and urban areas. In the analysis of the impacts of natural hazards, three broad categories have been defined: 1) focus on natural hazard's biophysical impacts because of the place it occurs; 2) focus on hazard's impacts on societies that experience the hazard because of the social characteristics of those societies and 3) an approach that takes into account both of impacts. This article takes the second approach to analyze the effects of natural hazards. In this approach, social characteristics of the communities and societies, in which earthquake happens, come to center stage. Social vulnerability is one of the important aspects of earthquake risks and consequences. In addition, the progress of communication and transportation technologies and an increase in agricultural production surplus because of the Industrial Revolution has caused many rural settlers to migrate to cities. The increasing population raise in cities has led to many economic, social and environmental consequences, of which excessive horizontal and leapfrog development (which is called urban sprawl in scientific literature) is one. In this article urban sprawl is defined as: "unplanned, far-from-center and automobile-accessed growth of cities which has environmental, economic and social effects and is characterized by low density, segregation of land-uses and limited accessibility". In this research, at first theoretical literature of urban sprawl and social vulnerability were reviewed and the indicators for measuring them were chosen (13 for urban sprawl and 7 for social vulnerability) and the relevant data for Qazvin was extracted by using national census data and Geographic Information System (GIS). Then explorative factor analysis for eigenvalues bigger than 1 was conducted by using SPSS software and the indicators for sprawl were categorized into 4 factors: “density”, “configuration”, “land-use” and “accessibility” (70.22% of variance explained), and the indicators for social vulnerability were grouped in 1 factor: social vulnerability (66.9% of variance explained). Then the maps for each factor of sprawl and two main topics (sprawl and social vulnerability) were made. The correlation analysis was conducted on four factors of sprawl, social vulnerability factor (which is representative of social vulnerability altogether) and sprawl as a whole. The results show that from 4 factors of sprawl, just density factor has a significant correlation (0.801) with social vulnerability. Sprawl is also significantly (although weaker) correlated to social vulnerability (0.44). In addition, regression analysis showed that four factors of sprawl can explain 67.6% of the variance of social vulnerability. The relation between social vulnerability and density/sprawl is positive/negative, i.e. by an increase in density/decrease in sprawl, social vulnerability increases. Finally, the maps of sprawl and social vulnerability in Qazvin city districts and the map of potential districts for development are shown based on the correlation of sprawl and social vulnerability.