Safe City

Safe City

Determining the Urban Region Using the Gravity Method (Measurement of Flows and Distance from the Center) and Resilience Analysis of Urban Areas (Case Study: Semnan Urban Region)

Document Type : Original Article

Authors
Askari Mojtahedzadeh 1
Zeinab Karkehabadi 2
Saeid Kamyabi 3
1 Ph.D. Candidate, Islamic Azad University, Semnan Branch.Semnan.Iran
2 Associate Professor, Islamic Azad University, Semnan Branch. Semnan. Iran
3 Associate Professor, Islamic Azad University, Semnan Branch , Semnan.iran
10.22034/ispdrc.2022.702213
Abstract
The development and expansion of urbanization in the twentieth century has led to the formation of
different spatial organizations in urban and regional patterns. Semnan city with a strategic position in the
country's communication network and proximity to the capital and industrial, mining and agricultural
potentials due to changes and implementation of political divisions in the last decade and the promotion
of small towns around Semnan to the city without paying attention to interconnections and demarcations
performance encountered. Existence of flows of goods, manpower, and interurban and peripheral services
represents a range of activities that cannot be stopped within local boundaries. This study has used the
gravity method (measurement of flows and distance from the center) to determine the boundaries of
Semnan urban area and its purpose is to determine the boundaries of Semnan urban area based on
functional relationships. From the city center of Semnan, a radius of 20 and 50 km was hit in GIS, the city
of Semnan was selected as the main city and the cities of Dargzin, Sorkheh, Shahmirzad and Mahdishahr
were selected as the surrounding cities. In the flow measurement method, the amount of population
displaced between the two cities and the amount of goods displaced were calculated and the final score
(iT) of each city was calculated by including the relevant formulas. According to calculations, the cities
of Sorkheh and Dargzin are with moderate correlation, Mahdishahr with high correlation and Shahmirzad
with very high correlation with Semnan. In the method of distance from the center to determine the
boundaries of Semnan urban area, a suitable distance for the maximum distance that Semnan city can
affect the surrounding urban areas while maintaining the nature of its city-regions (the easiest time to
reach the main city) is specified. Besides, cities that have the desired level of points are located in the
urban area using this method. From the overlap of the maps obtained from the methods of measuring
flows and distance from the center in GIS, Semnan urban area was determined based on statistical
functional relationships and the area of Semnan urban area consisting of Semnan, Dargzin, Sorkheh,
Shahmirzad and Mahdishahr cities. The total resilience level in Semnan region is equal to 3.21, lower
than the average of 3.5. As it was said before, only the social and cultural dimension is resilient and in
terms of other dimensions, especially the economic and institutional management dimensions, resilience
is at a very low level. 
Keywords
Gravity method
Measurement of flows
Distance from the center
Urban area
And resilience analysis of urban areas
Semnan
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