Vulnerability Analysis of Facilities Against Flood with Emphasis on AHP Fuzzy Method (Case Study: Khorramabad City)

جغرافیا و مخاطرات محیطی

Article 6, Volume 14, Issue 1 - Serial Number 53, March 2025, Pages 99-122   

Document Type: Research Article

DOI: 10.22067/geoeh.2025.89239.1506

Authors

Amir Rahimi¹; Mahin Nastaran^{* 2}

¹Master of Urban Planning, Faculty of Architecture and Urban Planning, Art University of Isfahan, Isfahan, Iran

²Associate Professor, Department of Urban Planning, Faculty of Architecture and Urban Planning, Art University of Isfahan, Isfahan, Iran

Abstract

Floods are known as one of the most common and destructive natural disasters due to their widespread destruction and huge economic losses. Khorramabad city is one of the cities at risk of flooding due to its experiences of floods in recent years, its location in a valley, heavy rains, the presence of rivers in the city (Khorramrod and Karganeh), and manipulation of the boundaries and beds of rivers. Therefore, investigating flood vulnerability plays an important role in reducing the damages and risks caused by floods.
One of the methods for investigating and analyzing flood vulnerability and urban facilities exposed to floods is the use of the fuzzy analytic hierarchy process (FAHP) to identify flood-prone and flood-vulnerable areas. Therefore, in this research, the fuzzy analytic hierarchy process method was used to prioritize the criteria. In this research, 12 criteria (worn texture, population density, road network, land use, height, slope, direction of slope, geology, distance from the river, soil science, land subsidence, and rainfall) were used to prepare a map of flood-prone and vulnerable areas.
The results of the analysis in this research showed that 38.17% of urban facilities are exposed to high and very high vulnerability, and administrative, commercial, and educational facilities have the highest level of vulnerability compared to other land uses to flooding. To reduce vulnerabilities, especially those of facilities to flooding, suggestions include improving the physical quality of urban facilities and buildings, organizing and improving the quality of river beds and boundaries, improving the condition of drainage, and using smart and advanced technologies to predict and warn of floods in order to reduce vulnerabilities.
Extended Abstract
Introduction
Floods are among the most catastrophic natural hazards that can cause huge economic losses, damage to infrastructure and natural ecosystems, as well as death. Therefore, investigating flood vulnerability plays an important role in reducing the damages and risks caused by floods. A flood is a sudden flow of water that flows at high speed in a short time and causes destruction along with financial and human losses.
Khorramabad city has experienced floods 12 times from 1976 to 2005. One of the largest floods in Lorestan province is the flood of 2019, with the initial estimate of flood damage in Lorestan province exceeding 15 trillion rials. Fifteen people lost their lives and about 256 people were injured, and the city of Khorramabad had a huge share of these damages and casualties. Khorramabad city is one of the cities at risk of flooding due to its experiences of floods in recent years, its location in a valley, heavy rains, the presence of rivers in the city (Khorramrod and Karganeh), and manipulation of the boundaries and beds of rivers.
Considering the experiences of flood risk in Khorramabad city and despite numerous studies conducted in the field of flooding in regions and cities, no research has been conducted so far on the vulnerability analysis of urban facilities, especially using the FAHP (Fuzzy Analytic Hierarchy Process) method. Therefore, the purpose of the present study is to analyze the vulnerability of facilities through the FAHP method and then to describe the application of the FAHP method in hazards and crises in order to reduce vulnerabilities.
Material and Methods
This paper is a descriptive-analytical study. This research was conducted in ArcGIS 10.5 and Expert Choice 11 software. Data collection methods included library methods (books, articles, information on the 2019 detailed plan of Khorramabad city, meteorological information, and data from the Iranian Geological Organization and the Natural Resources Administration) and field methods (questionnaire and observation).
The criteria effective in flood vulnerability were selected through library studies and urban experts according to the location and characteristics of Khorramabad city, which include 12 criteria (worn texture, population density, road network, land use, height, slope, slope direction, geology, distance from the river, soil science, land subsidence, and rainfall). After the criteria are determined by experts, the Analytic Hierarchy Process (AHP) method is used. The AHP is one of the most comprehensive methods designed for decision-making with multiple criteria. This method allows the problem to be formulated hierarchically. This method is based on three basic steps:

Creating a pairwise comparison matrix,
Calculating the weights of the criteria, and
Estimating the compatibility ratio.

Additionally, in this research, the fuzzy logic method was used to standardize the criteria. The fuzzy logic method is used to standardize the criteria in cases where the units of measurement have different ranges with ranges of similarity from 0 to 1.
Results and Discussion
After preparing the maps of the information layers, questionnaires were distributed among the experts, in which a pairwise comparison of the criteria was made based on the value (importance) in the numerical range between 1 and 9. Finally, after completing the questionnaire, a matrix was prepared in the Expert Choice software and the summary of the experts' opinions was added to that matrix. The output of the Expert Choice software analysis shows the weight of each criterion, and according to the AHP, the higher the weight of the criterion, the greater the importance and value of that criterion, and vice versa. According to the software output, population density, rainfall, distance from the river, height, and land use were the most important and scored.
The Geographic Information System (GIS) provides a wide range of spatial analysis, regional analysis, and network analysis capabilities on various thematic layers. In the present study, the AHP method was used to weight the criteria and determine the criteria in priority (importance) and standardization with the fuzzy logic method.
After preparing the weighted maps of the criteria (layers), by combining the weighted layer maps through ArcGIS software, using the SUM fuzzy operator, the map of vulnerable areas was determined in 5 vulnerability classes: very low, low, medium, high, and very high. By overlapping the distribution map of each facility with the flood vulnerability zoning map, all facilities can be analyzed for flood vulnerability.
With the analyses conducted, the vulnerability of facilities was determined in 5 levels of vulnerability, according to which, 9.66% and 28.51% of facilities are in the very high and high vulnerability range, respectively, and a total of 38.17% of facilities are exposed to high and very high vulnerability. According to the analyses conducted, using the percentage and total area of facilities exposed to flood vulnerability and considering the area of each facility, the vulnerability value of each facility was calculated.
Furthermore, with the analyses conducted, it can be concluded that administrative, commercial, and educational uses have the highest vulnerability to flooding with 39.47%, 12.78%, and 11.78%, respectively, and religious and cultural uses have the lowest vulnerability to flooding with 0.84% and 0.38%, respectively.
Conclusion
The results of the analysis of this research showed that 38.17% of urban facilities are exposed to high and very high vulnerability, and administrative, commercial, and educational uses have the highest level of vulnerability compared to other uses to flooding. To reduce vulnerabilities, especially reducing the vulnerability of facilities to flooding, suggestions can be made such as:

Improving the physical quality of urban facilities and buildings,
Organizing and improving the quality of river beds and boundaries,
Improving the condition of drainage, and
Using smart and advanced technologies to predict and warn of floods in order to reduce vulnerabilities.

Finally, by achieving the research objectives in order to explain the application of the FAHP method, other applications of this method in reducing vulnerabilities can be mentioned, such as:

Identifying zones and areas prone to vulnerability to crises,
Correct location of emergency services to provide services during crises,
Identifying and analyzing traffic nodes in times of crisis and correct routing in order for people to escape from crises and provide rapid services to people,
Locating and identifying temporary accommodation, parking lots, and safe shelters during crises, and
Correct location of urban facilities and residential areas to reduce vulnerabilities.

Previous research on the flood in Khorramabad city has addressed issues such as:

Investigating the cause of the Khorramabad flood incident,
Zoning of the entire city and villages, agricultural lands and roads, as well as
Examining the role of floods in changing river beds and their impact on rural communities.

The difference between the present research and other research conducted is in analyzing the vulnerability of Khorramabad city facilities to flooding. Moreover, the research conducted so far has not examined facilities because the issue of urban facilities is considered an important issue in the field of urban planning. Similarly, in this research, the combined method of FAHP, which is a relatively new method, was used. One of the applications of this method is the analysis of risks and crises.
 

Keywords

FLOOD VULNERABILITY; FUZZY AHP (FAHP); ARCGIS; KHORRAMABAD CITY; URBAN FACILITIES; RISK ASSESSMENT; SPATIAL ANALYSIS

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