پهنه‌بندی ناپایداری دامنه‌ها با استفاده از روش‌های تصمیم‌گیری SWARA و CRITIC در محدودۀ شهر تبریز

Extended Abstract 
Introduction
Landslide hazard zoning is a fundamental instrument for risk management and strategic decision-making in environmental planning, a task of particular importance in mountainous regions with complex and dynamic terrain. The metropolis of Tabriz, constrained by its geomorphological and topographical conditions, has historically pursued a sectoral development model. This growth strategy has driven the extensive construction and expansion of satellite towns around the city’s periphery. Many of these newly developed settlements—most notably Eram Town—are located in close proximity to the active fault line north of Tabriz. This precarious location exposes them to multiple natural hazards, including earthquakes, flash floods, and diverse forms of mass movements. These factors are widely acknowledged as critical indicators in geomorphological hazard assessments, a concern further compounded by the fact that many of these settlements are built on unstable slopes composed of weak and erodible lithology.
Due to the city’s mountainous topography and the prevalence of clay-rich, unstable soils, Tabriz is highly susceptible to diverse types of slope movements, from shallow landslides to deep-seated instabilities. Accordingly, this study pursued two main objectives: (1) to assess and zone slope instability within the metropolitan area of Tabriz, and (2) to develop a robust, generalizable model for systematic landslide hazard zoning. The proposed model is designed for application not only to Tabriz but also to neighboring areas with comparable geomorphological characteristics. To this end, the evaluation integrated nine key causative factors and employed two multi-criteria decision-making (MCDM) methods—Step-wise Weight Assessment Ratio Analysis (SWARA) and Criteria Importance Through Intercriteria Correlation (CRITIC)—to derive precise weightings.
 
Methodology
SWARA is a MCDM technique designed to determine the relative weights of criteria and sub-criteria.

Step 1: A decision model is developed based on the interrelationships among parameters. The criteria used to construct the slope instability zoning map are then ranked in descending order according to their perceived importance.
Step 2: The weights of the criteria are calculated as follows: beginning with the second criterion, the evaluator specifies the relative importance of criterion j in comparison with the preceding criterion (j-1). This procedure is repeated sequentially for all remaining criteria.

In contrast to many other approaches, the CRITIC method does not rely extensively on expert judgment. Indeed, its independence from subjective expert assessments is regarded as one of its principal strengths. The method evaluates data by measuring the degree of contrast and correlation among criteria. Each criterion is represented as a vector characterized by statistical parameters, including the standard deviation, which captures the variability in its values.
 
Results and Discussion
To assess the potential for slope movements, nine key factors were identified as critical triggers of instability in the region: slope gradient, aspect, lithology, land use, precipitation, proximity to faults, proximity to rivers, and proximity to roads.
The historic urban core of Tabriz was established on relatively flat terrain with gentle slopes. However, rapid urban expansion has extended development onto adjacent steep slopes, particularly in newly established satellite towns. These towns are predominantly located in the northern and southeastern sectors of the city, both of which are characterized by steep terrain. The most erosion-prone geological units include marl, shale interbedded with sandstone, and recent fluvial alluvium. By contrast, sandstone and red marl units display comparatively higher resistance to erosion, contributing to the rugged topography and elevated relief of the basin.
The eastern and northern sectors of the city are especially prone to landslides because of their distinctive geological composition. The prevalence of highly saturable marl and clay layers in these areas creates conditions that are highly conducive to slope instability. Precipitation intensifies slope instability through the combined effects of hydrological and mechanical processes. These effects are further amplified in areas characterized by steep gradients, erosion-prone lithology, and sparse vegetation cover. Zones located near fault lines are particularly vulnerable owing to concentrated tectonic stresses, intensified rock fracturing, and an elevated probability of micro-seismic activity.
The rapid physical expansion of the city has also generated severe traffic congestion. To address this issue, beltways were constructed to divert transit traffic beyond the urban limits, leading to the development of two major highways in northern and southern Tabriz. Although originally designed exclusively for transit purposes, these corridors have progressively acquired urban functions as the city expanded along their axes.
 
Conclusion
A careful comparison of the final hazard map with the landslide distribution map confirms the reliability of this study, as the high-risk zones correspond closely with historically recorded landslide events. Therefore, the methodology and model proposed in this study offer an effective framework for urban landslide hazard zoning. In particular, areas within the neighborhoods of Silab, Malazinal, Yousef Abad, Valiasr Alley, Baghmisheh Town, Golpark Alley, Shahid Yaghchian Town, Fajr Town, Khavaran Town, and Sayyad Shirazi Town fall within very high- and high-risk zones. Conversely, the southern and western sectors are largely classified as safe zones, whereas substantial portions of the northern and eastern sectors are designated as low-risk areas.
Considering the ongoing physical and structural expansion of Tabriz, along with its increasing population, urban development requires careful management. Specifically, uncontrolled urban expansion into areas affected by the North Tabriz Fault System has heightened the city’s susceptibility to earthquakes and related geomorphological hazards, including slope instability. To mitigate future hazards, long-term urban planning should impose restrictions on development within high-risk zones. Furthermore, policymakers are advised to establish incentive programs that encourage at-risk residents to relocate to safer locations, thereby reducing their exposure to landslides and other geological hazards.
 
Funding
Tabriz Metropolitan Islamic Council Research Center.
 
Authors’ Contribution
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
We are grateful to all the scientific consultants of this paper. This article is the result of research conducted at the University of Tabriz with financial support from the Islamic Council of Tabriz Metropolitan Research Center. The authors hereby sincerely thank the efforts of the Technology Management of the University of Tabriz, especially Dr. Nadiri and Mr. Hessami, the Director of the Islamic Council of Tabriz Metropolitan Research Center, Dr. Rouhollah Rashidi, and the Deputy Director of Research, Dr. Ahad Ebrahim Pour-Lanbaran, as well as the scientific supervisors of the project, Dr. Morad Ali Shafaghi and Dr. Roghieh Salek.
ABSTRACT
Slope instability represents one of the most severe natural hazards, leading to substantial economic damage and human casualties each year, while also posing considerable challenges for infrastructure development. This study seeks to identify the key factors driving slope instability and to outline preventive strategies within the metropolitan area of Tabriz, a case of particular significance for environmental and urban planning. The research applied the SWARA and CRITIC multi-criteria decision-making methods to weight and evaluate the selected criteria, and subsequently produced a hazard zonation map using ArcGIS. The analysis considered multiple criteria, including slope, aspect, elevation, proximity to faults, rivers, and roads, as well as lithology, land use, and precipitation. Following the weighting process, the criteria were standardized and converted into thematic layers. These layers were then integrated and overlaid to generate the final zonation map identifying areas susceptible to slope movements. The results indicate that the unstable zones delineated by both models largely correspond to locations of previously recorded landslides. Specifically, neighborhoods such as Silab, Malazināl, Yusefabad, Kuy-e Valiasr, and Kuy-e Golpark, along with residential districts including Baghmesheh, Yaghchiyan, Fajr, Khavaran, and Sayyad Shirazi, are located within very high- and high-hazard zones. By contrast, the western, northwestern, and southwestern sectors of the city are classified as safe zones, whereas the central and eastern sectors are predominantly categorized as low-hazard.
Extended Abstract 
Introduction
Landslide hazard zoning is a fundamental instrument for risk management and strategic decision-making in environmental planning, a task of particular importance in mountainous regions with complex and dynamic terrain. The metropolis of Tabriz, constrained by its geomorphological and topographical conditions, has historically pursued a sectoral development model. This growth strategy has driven the extensive construction and expansion of satellite towns around the city’s periphery. Many of these newly developed settlements—most notably Eram Town—are located in close proximity to the active fault line north of Tabriz. This precarious location exposes them to multiple natural hazards, including earthquakes, flash floods, and diverse forms of mass movements. These factors are widely acknowledged as critical indicators in geomorphological hazard assessments, a concern further compounded by the fact that many of these settlements are built on unstable slopes composed of weak and erodible lithology.
Due to the city’s mountainous topography and the prevalence of clay-rich, unstable soils, Tabriz is highly susceptible to diverse types of slope movements, from shallow landslides to deep-seated instabilities. Accordingly, this study pursued two main objectives: (1) to assess and zone slope instability within the metropolitan area of Tabriz, and (2) to develop a robust, generalizable model for systematic landslide hazard zoning. The proposed model is designed for application not only to Tabriz but also to neighboring areas with comparable geomorphological characteristics. To this end, the evaluation integrated nine key causative factors and employed two multi-criteria decision-making (MCDM) methods—Step-wise Weight Assessment Ratio Analysis (SWARA) and Criteria Importance Through Intercriteria Correlation (CRITIC)—to derive precise weightings.
 
Methodology
SWARA is a MCDM technique designed to determine the relative weights of criteria and sub-criteria.

Step 1: A decision model is developed based on the interrelationships among parameters. The criteria used to construct the slope instability zoning map are then ranked in descending order according to their perceived importance.
Step 2: The weights of the criteria are calculated as follows: beginning with the second criterion, the evaluator specifies the relative importance of criterion j in comparison with the preceding criterion (j-1). This procedure is repeated sequentially for all remaining criteria.

In contrast to many other approaches, the CRITIC method does not rely extensively on expert judgment. Indeed, its independence from subjective expert assessments is regarded as one of its principal strengths. The method evaluates data by measuring the degree of contrast and correlation among criteria. Each criterion is represented as a vector characterized by statistical parameters, including the standard deviation, which captures the variability in its values.
 
Results and Discussion
To assess the potential for slope movements, nine key factors were identified as critical triggers of instability in the region: slope gradient, aspect, lithology, land use, precipitation, proximity to faults, proximity to rivers, and proximity to roads.
The historic urban core of Tabriz was established on relatively flat terrain with gentle slopes. However, rapid urban expansion has extended development onto adjacent steep slopes, particularly in newly established satellite towns. These towns are predominantly located in the northern and southeastern sectors of the city, both of which are characterized by steep terrain. The most erosion-prone geological units include marl, shale interbedded with sandstone, and recent fluvial alluvium. By contrast, sandstone and red marl units display comparatively higher resistance to erosion, contributing to the rugged topography and elevated relief of the basin.
The eastern and northern sectors of the city are especially prone to landslides because of their distinctive geological composition. The prevalence of highly saturable marl and clay layers in these areas creates conditions that are highly conducive to slope instability. Precipitation intensifies slope instability through the combined effects of hydrological and mechanical processes. These effects are further amplified in areas characterized by steep gradients, erosion-prone lithology, and sparse vegetation cover. Zones located near fault lines are particularly vulnerable owing to concentrated tectonic stresses, intensified rock fracturing, and an elevated probability of micro-seismic activity.
The rapid physical expansion of the city has also generated severe traffic congestion. To address this issue, beltways were constructed to divert transit traffic beyond the urban limits, leading to the development of two major highways in northern and southern Tabriz. Although originally designed exclusively for transit purposes, these corridors have progressively acquired urban functions as the city expanded along their axes.
 
Conclusion
A careful comparison of the final hazard map with the landslide distribution map confirms the reliability of this study, as the high-risk zones correspond closely with historically recorded landslide events. Therefore, the methodology and model proposed in this study offer an effective framework for urban landslide hazard zoning. In particular, areas within the neighborhoods of Silab, Malazinal, Yousef Abad, Valiasr Alley, Baghmisheh Town, Golpark Alley, Shahid Yaghchian Town, Fajr Town, Khavaran Town, and Sayyad Shirazi Town fall within very high- and high-risk zones. Conversely, the southern and western sectors are largely classified as safe zones, whereas substantial portions of the northern and eastern sectors are designated as low-risk areas.
Considering the ongoing physical and structural expansion of Tabriz, along with its increasing population, urban development requires careful management. Specifically, uncontrolled urban expansion into areas affected by the North Tabriz Fault System has heightened the city’s susceptibility to earthquakes and related geomorphological hazards, including slope instability. To mitigate future hazards, long-term urban planning should impose restrictions on development within high-risk zones. Furthermore, policymakers are advised to establish incentive programs that encourage at-risk residents to relocate to safer locations, thereby reducing their exposure to landslides and other geological hazards.
 
Funding
Tabriz Metropolitan Islamic Council Research Center.
 
Authors’ Contribution
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none.
 
Conflict of Interest
Authors declared no conflict of interest.
 
Acknowledgments
We are grateful to all the scientific consultants of this paper. This article is the result of research conducted at the University of Tabriz with financial support from the Islamic Council of Tabriz Metropolitan Research Center. The authors hereby sincerely thank the efforts of the Technology Management of the University of Tabriz, especially Dr. Nadiri and Mr. Hessami, the Director of the Islamic Council of Tabriz Metropolitan Research Center, Dr. Rouhollah Rashidi, and the Deputy Director of Research, Dr. Ahad Ebrahim Pour-Lanbaran, as well as the scientific supervisors of the project, Dr. Morad Ali Shafaghi and Dr. Roghieh Salek.