Investigation of Urban Sprawl Using Spatial Planning Models in Mashhad

Introduction and Background: Urban sprawl is a key subject of interest among urban planners and policy–makers, which needs to measure and monitor in order to overcome its impacts. In fact, urban expansion, and sprawl modeling is an interdisciplinary field as it involves numerous scientific areas such as geographical information system (GIS), complexity theory, urban geography, and remote sensing. Aims: The present study aims to generate an urban sprawl model using spatial planning approaches in Mashhad city. This type of measurement of physical growth in urban districts of Mashhad city is essential to urban planners and decision–makers who immediately need updated database for planning and management purposes. For this purpose, modified relative Shannon’s entropy together with hierarchical clustering analysis was considered. Five geo–statistical variables were considered as independent input variables to measure sprawl model. Thus, to reveal probability relations between sprawl indices and aforementioned independent variables the correlation coefficients were used. The results revealed an analogous output for both relative entropy measurement and hierarchical clustering analysis through the sprawl model. On this basis, three municipality districts were categorized as prone zones of the study area in regard of sprawl expansion pattern. A direct and significant correlation between sprawl indices and informal settlements was estimated equal to 0.44 through municipality districts. Also, direct correlations (R=0.32 to 0.30) were observed between sprawl index and frequency of crimes and building parcel size. Contrarily, the result revealed a reverse correlation (R=−0.50) between sprawl index and land price index was explored based on each districts. It seems that the sprawl expansion in these districts influenced the growth of informal settlements and increase of crimes. This phenomenon could trigger negative environmental and socio–economical impacts in the study area. Hence, the urban management in Mashhad city should control the sprawl expansion in the prone districts by environmental prevention of land use change and land degradation.