The analysis of permeability coefficient of the urban texture with an emphasis on non-operating defense (case Study: Gorgan City)

Many Iranian cities are located on areas with moderate and high risk of urban crises. Gorgan city is one of the most vulnerable cities to earthquakes, drift, landslides, and etc. The geostrategic situation, the location of a part of the city on a steep slope, inattention to standards and norms in the radius of access to permeability indicators, inertial growth and inappropriate distribution of services in the city, inadequate access to the passage network and inadequate physical structure are the factors that necessitate to address the permeability of the urban texture of Gorgan city in the face of possible damage.The present study is an applied study with a descriptive-analytical method.In order to achieve the research goal, permeability indicators were extracted from relevant experts according to available resources and field studies through a hierarchical analytical method and data banks. In addition, the permeability of the indicators was measured based on non-active defense principles.Considering the different effects of the indices, the AHP-FUZZY method was used in the GIS environment to evaluate and prepare the permeability map of the city. Using the ARC GIS10.3 software, urban texture permeability of Gorgan was prepared through the overlap of final Raster Fuzzy. According to the findings of the research, about 50.40% of the Southern and marginal areas of Gorgan are exposed to low permeability and high vulnerability due to a large slope, low vacancy spaces, and a shortage of passageways, high density of bays and the density of bridge bridges against emergencies and possible urban damages.