@2024 Afarand., IRAN

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ISSN: 2538-4384    Geographical Researches 2020;35(4):293-306

Background
The evaluation of the vulnerability in a city is a kind of prediction of the possible damages in case of an earthquake.
Previous Studies
The urban vulnerability has been assessed from various vie points. Dadbood & Zangiabadi (2019) analyzed the vulnerability of Gorgan's physical fabric using AHP, ANP, and Vikor models. Isalou et al. (2017) analyzed the vulnerability of district 1 in Tehran using population density, land uses risks, buildings quality, buildings age, and access to emergency centers. Ma & Ohno (2018) evaluated the vulnerability of Tianjin city using the indicators of buildings height, abundant entrances of the neighborhoods, the width of the passages, buildings condition, infrastructure conditions, and enclosure of the passages. Bahraini et al. (1996) used various indicators for land use planning.
Aim(s)
This study aimed to evaluate the vulnerability of the physical fabric of Hashtgerd new city against the earthquake.
Research type
This is an empirical study carried out using the descriptive-analytical methodology.
Research society, place and time
The current research is carried out in Hashtgerd city using the elite opinion.
Sampling method and number
10 elites were chosen to express their opinion in the current research.
Used devices&materials
The questionnaire was used for data collection, GIS software was used for the determination of the endangered zones, and the AHP method in Expert Choice software.
Findings by Text
According to the previous studies in the field of urban fabric vulnerability, the indicators of population and buildings density, buildings age, materials quality, land uses risks, access to the emergency centers, access to the green spaces, passages condition, distance from the faults, slope, and buildings and infrastructures condition were the most frequent ones and can be considered as the important and influential ones. To select the most important ones from the mentioned indicators, the importance ranking in the Likert spectrum was used to show the elites' opinions. Finally, eight indicators were chosen (Table 1). To weight each indicator and show its importance in the urban crisis maps, they were compared in pairs using the AHP method in Expert Choice software. The comparison was done according to the elites' score and the abundance of the indicators in the previous studies (Figure 1). To prepare the urban physical vulnerability layers, each chosen indicator (distance from the fault, access to the green space, population and buildings density, land use, and passages) were classified in five levels of vulnerability (very low, low, medium, high, and very high). Access to the green space: Hashtgerd new city has an array of gardens and farms as well as parks. Fashand village in the northern part of the city has a lot of outdoor space [Paykade Consulting Engineers, 2010]. Because of the scattered constructions in the city, there is numerous space to change them into green space. Such spaces are not facilitated to provide the needed facilitates such as water and fuel tanks in case of earthquakes. The green space density was estimated to evaluate the urban fabric flexibility to assess the vulnerability of the city in terms of access to the green space. The green space and the outdoor space are of great importance in the reduction of the vulnerability in time of the earthquake. According to the map in Figure 4, shows a high proportion of the city (73.47%) does not have enough green space. The current total available green space in Hashtgerd new city is 88223〖km〗^2 [Paykade Consulting Engineers, 2010]. There is a population of 15736 people in the city. As everyone needs 2m^2 space after the disasters [Zhang, 2019], the residents of Hashtgerd new city need almost 31482m^2 after the earthquake. Then there is enough green space in the city but it is not distributed fairly. Population and buildings density: Hashtgerd city is getting more populated gently. There are lots of empty buildings and some of the residents have left the city due to the lack of enough facilities [Yaran & MohammadiKhoshbin, 2012]. However, there is more population around the main entrance of the city that is more facilitated (Figure 5 & Figure 6). To prepare the maps, the density of the population and the buildings were calculated. According to the maps, this city is in good condition in terms of the population and buildings distribution. Less than 1% of the city is in levels of high and very high vulnerability. Land use: industrial land use and urban infrastructures are incompatible with most of the available urban land uses [Bahraini et al., 1996]. Then, the land uses density was calculated to prepare the urban vulnerability map [Figure 7]. According to the map, the most incompatible land uses are located in block number 4 (Mehr housing) of Hashtgerd new city. Distance from emergency centers: the more distant from the emergency centers, the more vulnerable and vice versa. Then the distance of all parts of the city from the emergency centers was calculated (Figure 8). According to the results, the city is in good condition in terms of the distance from emergency centers. However, the shortage of hospitals and crisis management organizations should be taken into consideration. Passages condition: the passages' width and the distance from them are influential in the city's vulnerability. The more distant from the passages, the more vulnerable. Since it is less possible to run away, evacuate the injured and killed people. To evaluate the vulnerability, the distance of all parts of the city from the passages is calculated (Figure 9). The passages' width shows their capacity to move and help people. The wider the passages, the less vulnerability (Figure 10). According to the evaluations, Hashtgerd is not in good conditions in terms of the passages' width (especially in Blocks 5 and 7), while the distribution of the passages is good. Distance from the fault: there are two faults in Hashtgerd new city. One of them crosses the city center with the most population density and the other one is located in the northern east (near Block 2) with the most building density (Figures 5, 6, and 11). The distance of all parts of the city from the fault is measured to prepare the vulnerability map (Figure 11). According to the results, Hashtgerd is in critical conditions in terms of the distance from the fault. More than half of the city (Blocks 1, 2, 4, and 5) are adjacent to the faults and are densely constructed. Crisis zoning: the crisis zoning map was prepared by overlaying the vulnerability layers of access to the green space, population density, building density, land use, access to the passages, distance from the faults, and passages' width with significance factors of 0.1, 0.76, 0.74, 0.60, 0.56, 0.83, and 0.60, respectively (Figure 12). According to Table 2, the vulnerability of 81.4% of the city is in good and medium conditions. Various measures can be taken to resolve the current vulnerabilities. The city is new and it is a good opportunity to solve the problems and manage the situation. However, blocks 1, 2, 3 and some parts of block 4 are in critical conditions in time of the earthquake.
Main comparison to the similar studies
The green space bad condition is problematic in some other new cities. The green space per capita in Andishe new city is not enough for the population living there [Farhadkhah et al., 2016]. The population settled in this city is more than the primary predictions [Ghanavati et al., 2010]. Lack of enough attention to the optimal placement of incompatible land uses in Andishe new city is also another problem [Ghanavati et al., 2010]. Despite the environmental safety and crisis management policies that pay special attention to the possible natural and artificial disasters in new cities, the placement of new cities faces severe problems [New Towns Development, 2017]. The results of the current research are consistent with the results of Isalou (2017). According to their results, the northern part of district 1 of Tehran is one of the most vulnerable and dangerous spots because of the narrow passages, dense population, northern fault of Tehran, dangerous land uses such as the gas stations in residential zones, and lack of enough access to the emergency centers. Bhattarai & Conway (2010) achieved similar results about the evaluation of the urban fabric vulnerability. They believe the narrow passages, dense constructions and unfair distribution of public transport are the most factors leading to more vulnerability in Nepal.
Suggestions
There is no suggestion reported.
Limitations
There is no limitation reported.
Conclusions
The preparations for the earthquake determines the city's condition after the earthquake. Passages condition, population and buildings density, the faults, and the available green space are the most influential factors in the evaluation of the vulnerability. Setting proper priorities is of great importance to make better decisions in time of disaster. According to the mentioned indicators, blocks 1, 2, 3, and some parts of block 4 which are located around the main entrance of the city are vulnerable, while blocks 5 and 7 and Baghshahr are less vulnerable.
Acknowledgments
We tend to thank our interviewees at Shahid Beheshti University.
Conflict of interest
None
Ethical Permissions
None
Funding Sources
This article is extracted from Atousa Hasani M.A. thesis at Shahid Beheshti University under supervision of Dr.Fallah. This paper is carried out on personal expense of the second author.

TABLES and CHARTS

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