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Volume 37, Issue 2 (2022)
GeoRes 2022, 37(2): 253-266 |
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Received: 2022/01/26 | Accepted: 2022/03/18 | Published: 2022/04/8
Received: 2022/01/26 | Accepted: 2022/03/18 | Published: 2022/04/8
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Shiripour M, Sasanpour F, Fassihi H, Shamai A. Assessing the Role of Spatial Structure of Metropolises in Environmental Resilience of Tabriz Metropolis by Fuzzy MABAC Method. GeoRes 2022; 37 (2) :253-266
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1- Department of Human Geography, Faculty of Geography, Kharazmi University, Tehran, Iran
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Introduction
In recent years, resilience has become a major concern for cities, particularly those exposed to natural hazards and potential human-induced threats. Resilience enables cities to prepare for both foreseeable and unforeseen events, to cope with and adapt to them, and to continue progressing toward long-term objectives (Motamedi & Yapang Gharavi, 2020). The global association of major cities, Metropolis, emphasizes that achieving urban resilience requires a holistic perspective on the city and a sound understanding of its systems, inefficiencies, and potential risks. Only through strengthening urban structures and improving the understanding of shocks can cities sustain development pathways and enhance citizens’ well-being (Honey-Rosés et al., 2020). For instance, the COVID-19 pandemic demonstrated that many cities lack adequate and resilient mechanisms to confront sudden events such as biological hazards (Glaeser, 2021). Patterns of mobility, activity, and coexistence within dense urban settlements significantly influence the resilience of the urban environment. Accordingly, understanding the spatial structure of cities and identifying its relationship with urban environmental resilience is of considerable importance.
Inefficiencies and functional weaknesses in spatial structure can lead to serious urban problems, making it difficult to meet citizens’ basic needs (Omidpour et al., 2020), while environmental issues increasingly affect different parts of cities. Urban dynamism and vitality are directly related to the way spatial elements are structured (Ghadami et al., 2013). Urban spatial structure also plays a decisive role in quality of life, levels of urban resilience during acute and long-term crises, environmental crises, and public health. Factors such as inappropriate land-use allocation, poor building design and construction, inefficient urban infrastructure, inadequate accessibility due to unequal distribution of facilities, outdated and inefficient transportation systems, imbalances in population and activity distribution, and unbalanced transport networks can increase risks to human settlements and undermine their resilience (Tucker et al., 1994). Moreover, the spatial structure of metropolitan areas regulates urban mobility patterns and determines dependence on motorized transportation (Hashemi, 2021). It reflects the distribution of activity and residential centers, and these spatial patterns can significantly affect environmental quality (Meshkini et al., 2017). The intensity and type of space use within cities influence environmental conditions; therefore, urban spatial structure is closely intertwined with environmental quality and urban health and, over time, shapes the urban environment.
Over recent decades, numerous studies have addressed urban resilience as well as the decline in capacity and quality of urban environments. Drawing on key research in environmental resilience and urban ecology, the present study reviews major findings and practical experiences reported in the literature. These studies inform the identification of indicators, the definition of the research methodology, and the examination of the effects of the spatial structure of Tabriz on its urban environment.
The synthesis of prior research indicates that transformations in physical elements and spatial systems lead to changes in spatial processes, replacing traditional patterns with new forms of urban life, including mobility systems and activity patterns. Where the components of urban spatial structure are aligned with the city’s ecological system, urban capacity and resilience are not only preserved but may even be enhanced. Conversely, when urban development is incompatible with ecological systems and environmental conditions, urban resilience, particularly environmental resilience, declines.
From a theoretical perspective, diverse viewpoints address what urban spatial structure is, how it is formed, and how it affects urban and environmental resilience. The diversity of theories stems from the multiple factors involved in shaping urban form. Scholars have examined spatial structure from different angles to explain the mechanisms underlying urban formation. Among quantitative approaches, spatial configuration analysis is widely used to identify urban spatial structures. In this study, space refers to geographic space at a large scale, whose structure extends beyond the scale of direct human observation (Long, 2007). The most influential framework for analyzing urban spatial structure is space syntax theory, which posits that spatial configuration and the integration of urban spaces fundamentally shape the distribution of socio-economic activities, including commercial land uses, ethnic patterns, crime distribution, and movement flows (Hillier, 2007). Key analytical parameters in this approach include spatial integration, depth, connectivity, and choice (Serra & Pinho, 2011). Another relevant perspective is Peter Hall’s theory, which interprets spatial structure through the distribution of service, commercial, tourism, and industrial land uses (Burgalassi & Luzzat, 2015). In the domain of environmental urban resilience, theories of environmental carrying capacity and urban ecology provide the basis for identifying resilience components.
Based on these theoretical foundations and empirical experiences, the present research addresses the issue that the metropolitan area of Tabriz has undergone rapid physical and population growth in recent decades, accompanied by significant transformations in its spatial structure. One of the city’s major challenges is the existence of a strong central core that concentrates supra-local and urban activities, thereby attracting extensive regional travel flows (Piri & Saremi, 2018). The current spatial structure has increased reliance on motorized transport and reduced the effectiveness of pedestrian-oriented development strategies (Environmental Role Consulting Engineers, 2016). Rapid physical expansion without a coherent and efficient structure has increased distances between residential and activity centers, resulting in environmental consequences such as pollution concentration in activity hubs, waste accumulation, and wastewater management problems in residential areas. Residents are compelled to travel long distances daily to meet their needs, leading to increased intra-urban mobility, time and cost losses, and heightened environmental pollution (Karimi Rahnama et al., 2020). Although the existing spatial patterns are largely shaped by economic considerations and historical developments, environmental capacity and urban resilience have often been overlooked. Consequently, environmental resilience is expected to deteriorate further, potentially leading to systemic urban crises in the future. Understanding the role of spatial structure in shaping urban environmental resilience can therefore challenge prevailing car-oriented, capital-driven, and growth-centered development paradigms and provide alternative theoretical explanations. Accordingly, this study aims to examine the impact of the spatial structure of metropolitan Tabriz on urban environmental resilience.
Methodology
This research was applied in purpose and descriptive–analytical in method. The spatial scope of the study was metropolitan Tabriz, and the temporal scope covered the year 2020 and the first half of 2021. Data were collected through both fieldwork and documentary sources, including the urban street network from the comprehensive and detailed plans, land-use data from the comprehensive plan, and population block data derived from the national census. To assess the environmental resilience of central urban areas, eleven resilience parameters were employed.
Data analysis methods included kernel density estimation, space syntax analysis, standard deviation ellipse analysis, and the Fuzzy MABAC multi-criteria decision-making technique. The MABAC method, introduced by Pacumar and Cirovic (2015), is a recent approach for ranking alternatives in multi-criteria decision-making. The procedure involves defining criteria and alternatives, constructing and normalizing the decision matrix, weighting the normalized matrix, determining the boundary approximation area using geometric means, calculating distances between alternatives and the boundary area, and finally computing overall scores to rank alternatives.
Study Area
The study area is metropolitan Tabriz, covering approximately 131 square kilometers. It is located between 46°11′ and 46°23′ east longitude and 38°01′ to 38°09′ north latitude, at an average elevation of about 1,340 meters above sea level, within the Tabriz plain (Environmental Role Consulting Engineers, 2016). Tabriz is the third-largest city in Iran in terms of area, following Tehran and Mashhad.
Findings
The determinants of the spatial structure of the metropolitan area of Tabriz can be summarized as follows.
Analysis of urban spatial structure using the activity-center approach.
Various theories were proposed to explain the components of urban spatial structure. Among the most influential were the approaches of Peter Hall and Hillier, which conceptualized spatial structure as a function of the distribution of activity-based land uses and the hierarchical organization of the urban street network. In Peter Hall’s framework, urban activities were categorized into five main functional groups: Administrative–financial, tourism, commercial, public services, and industrial uses. In this study, this approach was first applied to examine the spatial structure of Tabriz.
The activity-based land uses were classified into five groups, and their spatial distribution was analyzed using kernel density estimation. The results indicated that administrative uses exhibit the highest level of concentration in the central part of the city. Tourism and recreational centers were likewise predominantly concentrated in the urban core. Commercial land uses also displayed their highest density in the central area. Other public uses, such as educational, healthcare, religious, and cultural facilities, showed a similar pattern, with strong concentration in the city center. In contrast, the spatial distribution of industrial land uses differed markedly from the other activity centers, as these uses were primarily located along the urban periphery, particularly in the western and northwestern sectors. Analysis of the overall distribution pattern demonstrated that the five activity groups were generally concentrated in the central area, indicating the presence of a dominant urban core, while surrounding areas mainly function as residential zones.
Analysis of spatial structure using spatial configuration methods.
To complement the activity-based analysis, spatial configuration analysis was employed to better understand the spatial structure of Tabriz. This analysis focused on spatial integration as the core concept of space syntax, in which street segments are treated as relational spaces interconnected within a network. In addition to spatial integration, spatial depth was examined, as these two concepts are inversely related.
The results revealed that streets leading toward the city center exhibited the highest levels of spatial integration. Major east–west and north–south corridors, along with streets connecting to the historic core and central market area, demonstrated particularly strong integration values. This pattern suggested that the opening and expansion of vehicular streets around the historic core have shifted spatial integration from the traditional center toward adjacent arterial roads. Overall, the city’s main thoroughfares showed significantly higher integration than peripheral streets, while areas surrounding the central core had moderate levels of integration. The findings confirmed that the most integrated streets played a dominant role in shaping urban movement patterns and attracting activities, thereby constituting the backbone of Tabriz’s spatial structure.
Further analysis of street connectivity indicated that the highest levels of intersection connectivity are associated with the main arterial corridors, which function as the most influential elements in the spatial organization of the city. As expected, the functional heart of the city exhibits the highest degree of global spatial integration.
Analysis of spatial structure based on population distribution.
Population density and its spatial distribution constituted another fundamental component of urban spatial structure. Population concentrations evolved over time and space through interactions with technological development and socio-economic processes. Accordingly, population density distribution was used as an additional indicator for identifying the spatial structure of Tabriz. The results showed that the highest population concentrations are located around the central parts of the city, with particularly high densities in the northern districts.
Assessment of urban environmental resilience using the Fuzzy MABAC method.
To evaluate environmental resilience in key spatial elements of metropolitan Tabriz, resilience criteria were quantified based on the area of different land uses, municipal archival data (including traffic levels, estimated waste generation, and air quality), and field observation checklists (covering waste bin availability, environmental hygiene, green space conditions, and physical fabric quality). These indicators were standardized on a five-point scale, allowing the environmental resilience status of different urban centers to be assessed.
After standardization, the criteria were weighted using a fuzzy weighting approach. A normalized decision matrix was then constructed, followed by the derivation of a weighted normalized matrix. Subsequently, the boundary approximation area was calculated using the MABAC technique, and the distances of each spatial element from this boundary were determined. Based on the resulting Q values, the spatial elements were ranked according to their influence on urban environmental resilience. The results indicated that commercial centers rank highest in terms of their impact on environmental resilience, followed by industrial centers and highly integrated road corridors. Public centers exhibited a moderate level of influence, while high-density residential areas, administrative centers, and tourism centers show relatively lower levels of environmental resilience.
Environmental impacts of the spatial structure of metropolitan Tabriz.
Several environmental consequences associated with the concentrated, monocentric spatial structure of Tabriz were identified.
Air pollution: One of the most prominent consequences of a centralized urban structure was increased air pollution, particularly in central areas. The findings indicated a rising trend in air pollution levels, largely driven by the rapid growth in motorized vehicle use. The concentration of service, commercial, and administrative activities in the urban core intensified daily traffic flows, leading to higher pollutant emissions. Areas that function as primary spatial cores exhibited the highest levels of air pollution, confirming the strong relationship between spatial concentration, traffic intensity, and environmental stress. Although significant residential populations were located in northern districts, the daytime concentration of activities in the city center resulted in greater congestion and air pollution in these central areas.
Distribution of particulate matter: Management of airborne particulate matter represented a key dimension of urban environmental resilience. Analysis of fine particulate matter concentrations indicated higher levels in western parts of the city, identifying these areas as major pollution zones. While southern and northern districts showed comparatively lower concentrations, the central area still exhibited elevated levels of airborne particulates, reflecting the cumulative effects of traffic, land-use concentration, and limited environmental capacity.
Environmental sustainability: Environmental sustainability constituted another important aspect of urban environmental resilience. Using data obtained from municipal environmental management sources, the sustainability status of different urban districts was assessed. The results showed notable spatial variation in environmental sustainability levels, with some districts exhibiting relatively high sustainability values, while others, particularly the central district fell into a condition of potential environmental instability. Overall, the metropolitan area of Tabriz demonstrated a moderate level of environmental sustainability, indicating that a substantial portion of the city is environmentally vulnerable and requires targeted interventions to enhance resilience.
Discussion
In this study, the relationship between the spatial structure of the city and the environmental resilience of Tabriz was examined. To this end, the interconnected processes of urban spatial elements were considered from a systems perspective. Since the city functions as a system composed of multiple components, any change in one spatial element can affect the performance of other elements and components of the system. Urban resilience, particularly urban environmental resilience, ensures the existence and survival of the urban system. In other words, the sustainability of urban systems is closely related to the quality of the natural urban environment. Although the urban environment is often considered a part of the urban system, in this study spatial elements, including the street network, activity–service centers, and population centers were regarded as the main components of the Tabriz urban system, and the relationships among these elements and the consequences of such interactions for urban environmental quality were examined.
In pursuing the research objective and adopting a systemic view of the functioning of Tabriz, the analysis of the city’s spatial structure yielded useful results. As shown, the various components forming the spatial structure of Tabriz, including the distribution of administrative, tourism, commercial, public, and industrial centers were not evenly distributed. The highest concentration of activity and service–recreational centers, except for industrial centers, was located in the city center, with lighter concentrations in areas surrounding the central zone. In other words, the spatial structure of Tabriz, based on the selected elements, was monocentric. It should be noted that while natural ecological conditions at the city scale may function relatively uniformly, the concentration of activity centers can disrupt such environmental conditions. In this way, the concentration of residents and their activities in a single part of the city can undermine the capacity and resilience of the urban environment. As the research findings indicated, air quality, noise pollution, and the amount of green space in the city center were lower than in peripheral areas. The results of this part of the study are consistent with the findings of Sobhani et al. (2019) and Esmailnejad et al. (2015).
The results also showed that urban environmental resilience is not limited to air pollution and particulate emissions. Increased environmental sensitivity to natural environmental factors, such as surface contamination from household and industrial waste disposal, soil and water erosion, reduction of green space due to increased building density, expansion of construction activities into deeper ground layers, and contamination of subsurface soil layers has contributed to a decline in urban environmental resilience. Field study results in metropolitan Tabriz indicate that buildings located along inner-city highways and households residing in the central areas were dissatisfied with noise pollution and air quality and tend to relocate away from the city center and farther from major streets. The fuzzy MABAC ranking also showed that commercial and industrial centers, with Q coefficients of 0.442 and 0.416 respectively, had high importance in urban environmental resilience. In other words, commercial and industrial centers exhibited greater sensitivity and higher potential for pollution compared to other parts of the city. Since the coefficients of these two parameters were positive, it can be concluded that increasing the volume and density of commercial and industrial land uses leads to an intensification of urban environmental problems and a reduction in resilience in these areas. High-density population centers, administrative centers, and tourism centers, due to their negative coefficients of −0.340, −0.233, and −0.347 respectively, had a lower impact on the environmental resilience of Tabriz. This part of the study is consistent with the findings of Niazi and Mohammadzadeh (2010).
Another set of findings revealed that the highest levels of air pollution and particulate matter are found in the central parts of the city. It was also determined that environmental resilience in central areas is lower than in peripheral zones. This reflects the vulnerable condition of the urban environment due to high traffic density and the excessive concentration of activities and fine-grained land parcels. While the spatial structure analysis showed higher levels of spatial integration and concentration of activity and service land uses in the city center, urban environmental assessment models also indicated that the city center experiences the highest levels of air pollution compared to other areas. Findings from other researchers further show that in the central part of the city, despite communication spaces occupying 21.6% of the urban fabric, they have failed to connect different parts of the city in a balanced and rational manner or to facilitate smoother movement. This area, by attracting more than 40% of total urban trips, experiences slower traffic flows, prolonged congestion, air and noise pollution, and traffic accidents more than any other part of the city. These results are consistent with the findings of Niazi and Mohammadzadeh (2010), Amadeh et al. (2018), and Karimi et al. (2020).
Conclusion
The conditions and quality of the urban environment in the central areas of Tabriz and their adjacent zones are characterized by instability and low resilience. The city’s spatial structure has led to an excessive concentration of trip-attracting land uses in this area, resulting in higher levels of traffic congestion and air pollution compared to other parts of the city.
Acknowledgments: The authors would like to express their gratitude to the staff of the Geographical Research journal.
Ethical Permission: There is nothing to report.
Conflict of Interest: This article is derived from the doctoral dissertation of Mehdi Shiripour, supervised by the second and third authors and advised by the fourth author.
Authors’ Contributions: Shiripour M (first author), Introduction Writer/Statistical Analyst (30%); Sasanpour F (second author), Introduction Writer/Methodologist (30%); Fassihi H (third author), Assistant Researcher (20%); Shamai A (fourth author), Assistant Researcher (20%)
Funding: The article was prepared independently and funded personally.
In recent years, resilience has become a major concern for cities, particularly those exposed to natural hazards and potential human-induced threats. Resilience enables cities to prepare for both foreseeable and unforeseen events, to cope with and adapt to them, and to continue progressing toward long-term objectives (Motamedi & Yapang Gharavi, 2020). The global association of major cities, Metropolis, emphasizes that achieving urban resilience requires a holistic perspective on the city and a sound understanding of its systems, inefficiencies, and potential risks. Only through strengthening urban structures and improving the understanding of shocks can cities sustain development pathways and enhance citizens’ well-being (Honey-Rosés et al., 2020). For instance, the COVID-19 pandemic demonstrated that many cities lack adequate and resilient mechanisms to confront sudden events such as biological hazards (Glaeser, 2021). Patterns of mobility, activity, and coexistence within dense urban settlements significantly influence the resilience of the urban environment. Accordingly, understanding the spatial structure of cities and identifying its relationship with urban environmental resilience is of considerable importance.
Inefficiencies and functional weaknesses in spatial structure can lead to serious urban problems, making it difficult to meet citizens’ basic needs (Omidpour et al., 2020), while environmental issues increasingly affect different parts of cities. Urban dynamism and vitality are directly related to the way spatial elements are structured (Ghadami et al., 2013). Urban spatial structure also plays a decisive role in quality of life, levels of urban resilience during acute and long-term crises, environmental crises, and public health. Factors such as inappropriate land-use allocation, poor building design and construction, inefficient urban infrastructure, inadequate accessibility due to unequal distribution of facilities, outdated and inefficient transportation systems, imbalances in population and activity distribution, and unbalanced transport networks can increase risks to human settlements and undermine their resilience (Tucker et al., 1994). Moreover, the spatial structure of metropolitan areas regulates urban mobility patterns and determines dependence on motorized transportation (Hashemi, 2021). It reflects the distribution of activity and residential centers, and these spatial patterns can significantly affect environmental quality (Meshkini et al., 2017). The intensity and type of space use within cities influence environmental conditions; therefore, urban spatial structure is closely intertwined with environmental quality and urban health and, over time, shapes the urban environment.
Over recent decades, numerous studies have addressed urban resilience as well as the decline in capacity and quality of urban environments. Drawing on key research in environmental resilience and urban ecology, the present study reviews major findings and practical experiences reported in the literature. These studies inform the identification of indicators, the definition of the research methodology, and the examination of the effects of the spatial structure of Tabriz on its urban environment.
The synthesis of prior research indicates that transformations in physical elements and spatial systems lead to changes in spatial processes, replacing traditional patterns with new forms of urban life, including mobility systems and activity patterns. Where the components of urban spatial structure are aligned with the city’s ecological system, urban capacity and resilience are not only preserved but may even be enhanced. Conversely, when urban development is incompatible with ecological systems and environmental conditions, urban resilience, particularly environmental resilience, declines.
From a theoretical perspective, diverse viewpoints address what urban spatial structure is, how it is formed, and how it affects urban and environmental resilience. The diversity of theories stems from the multiple factors involved in shaping urban form. Scholars have examined spatial structure from different angles to explain the mechanisms underlying urban formation. Among quantitative approaches, spatial configuration analysis is widely used to identify urban spatial structures. In this study, space refers to geographic space at a large scale, whose structure extends beyond the scale of direct human observation (Long, 2007). The most influential framework for analyzing urban spatial structure is space syntax theory, which posits that spatial configuration and the integration of urban spaces fundamentally shape the distribution of socio-economic activities, including commercial land uses, ethnic patterns, crime distribution, and movement flows (Hillier, 2007). Key analytical parameters in this approach include spatial integration, depth, connectivity, and choice (Serra & Pinho, 2011). Another relevant perspective is Peter Hall’s theory, which interprets spatial structure through the distribution of service, commercial, tourism, and industrial land uses (Burgalassi & Luzzat, 2015). In the domain of environmental urban resilience, theories of environmental carrying capacity and urban ecology provide the basis for identifying resilience components.
Based on these theoretical foundations and empirical experiences, the present research addresses the issue that the metropolitan area of Tabriz has undergone rapid physical and population growth in recent decades, accompanied by significant transformations in its spatial structure. One of the city’s major challenges is the existence of a strong central core that concentrates supra-local and urban activities, thereby attracting extensive regional travel flows (Piri & Saremi, 2018). The current spatial structure has increased reliance on motorized transport and reduced the effectiveness of pedestrian-oriented development strategies (Environmental Role Consulting Engineers, 2016). Rapid physical expansion without a coherent and efficient structure has increased distances between residential and activity centers, resulting in environmental consequences such as pollution concentration in activity hubs, waste accumulation, and wastewater management problems in residential areas. Residents are compelled to travel long distances daily to meet their needs, leading to increased intra-urban mobility, time and cost losses, and heightened environmental pollution (Karimi Rahnama et al., 2020). Although the existing spatial patterns are largely shaped by economic considerations and historical developments, environmental capacity and urban resilience have often been overlooked. Consequently, environmental resilience is expected to deteriorate further, potentially leading to systemic urban crises in the future. Understanding the role of spatial structure in shaping urban environmental resilience can therefore challenge prevailing car-oriented, capital-driven, and growth-centered development paradigms and provide alternative theoretical explanations. Accordingly, this study aims to examine the impact of the spatial structure of metropolitan Tabriz on urban environmental resilience.
Methodology
This research was applied in purpose and descriptive–analytical in method. The spatial scope of the study was metropolitan Tabriz, and the temporal scope covered the year 2020 and the first half of 2021. Data were collected through both fieldwork and documentary sources, including the urban street network from the comprehensive and detailed plans, land-use data from the comprehensive plan, and population block data derived from the national census. To assess the environmental resilience of central urban areas, eleven resilience parameters were employed.
Data analysis methods included kernel density estimation, space syntax analysis, standard deviation ellipse analysis, and the Fuzzy MABAC multi-criteria decision-making technique. The MABAC method, introduced by Pacumar and Cirovic (2015), is a recent approach for ranking alternatives in multi-criteria decision-making. The procedure involves defining criteria and alternatives, constructing and normalizing the decision matrix, weighting the normalized matrix, determining the boundary approximation area using geometric means, calculating distances between alternatives and the boundary area, and finally computing overall scores to rank alternatives.
Study Area
The study area is metropolitan Tabriz, covering approximately 131 square kilometers. It is located between 46°11′ and 46°23′ east longitude and 38°01′ to 38°09′ north latitude, at an average elevation of about 1,340 meters above sea level, within the Tabriz plain (Environmental Role Consulting Engineers, 2016). Tabriz is the third-largest city in Iran in terms of area, following Tehran and Mashhad.
Findings
The determinants of the spatial structure of the metropolitan area of Tabriz can be summarized as follows.
Analysis of urban spatial structure using the activity-center approach.
Various theories were proposed to explain the components of urban spatial structure. Among the most influential were the approaches of Peter Hall and Hillier, which conceptualized spatial structure as a function of the distribution of activity-based land uses and the hierarchical organization of the urban street network. In Peter Hall’s framework, urban activities were categorized into five main functional groups: Administrative–financial, tourism, commercial, public services, and industrial uses. In this study, this approach was first applied to examine the spatial structure of Tabriz.
The activity-based land uses were classified into five groups, and their spatial distribution was analyzed using kernel density estimation. The results indicated that administrative uses exhibit the highest level of concentration in the central part of the city. Tourism and recreational centers were likewise predominantly concentrated in the urban core. Commercial land uses also displayed their highest density in the central area. Other public uses, such as educational, healthcare, religious, and cultural facilities, showed a similar pattern, with strong concentration in the city center. In contrast, the spatial distribution of industrial land uses differed markedly from the other activity centers, as these uses were primarily located along the urban periphery, particularly in the western and northwestern sectors. Analysis of the overall distribution pattern demonstrated that the five activity groups were generally concentrated in the central area, indicating the presence of a dominant urban core, while surrounding areas mainly function as residential zones.
Analysis of spatial structure using spatial configuration methods.
To complement the activity-based analysis, spatial configuration analysis was employed to better understand the spatial structure of Tabriz. This analysis focused on spatial integration as the core concept of space syntax, in which street segments are treated as relational spaces interconnected within a network. In addition to spatial integration, spatial depth was examined, as these two concepts are inversely related.
The results revealed that streets leading toward the city center exhibited the highest levels of spatial integration. Major east–west and north–south corridors, along with streets connecting to the historic core and central market area, demonstrated particularly strong integration values. This pattern suggested that the opening and expansion of vehicular streets around the historic core have shifted spatial integration from the traditional center toward adjacent arterial roads. Overall, the city’s main thoroughfares showed significantly higher integration than peripheral streets, while areas surrounding the central core had moderate levels of integration. The findings confirmed that the most integrated streets played a dominant role in shaping urban movement patterns and attracting activities, thereby constituting the backbone of Tabriz’s spatial structure.
Further analysis of street connectivity indicated that the highest levels of intersection connectivity are associated with the main arterial corridors, which function as the most influential elements in the spatial organization of the city. As expected, the functional heart of the city exhibits the highest degree of global spatial integration.
Analysis of spatial structure based on population distribution.
Population density and its spatial distribution constituted another fundamental component of urban spatial structure. Population concentrations evolved over time and space through interactions with technological development and socio-economic processes. Accordingly, population density distribution was used as an additional indicator for identifying the spatial structure of Tabriz. The results showed that the highest population concentrations are located around the central parts of the city, with particularly high densities in the northern districts.
Assessment of urban environmental resilience using the Fuzzy MABAC method.
To evaluate environmental resilience in key spatial elements of metropolitan Tabriz, resilience criteria were quantified based on the area of different land uses, municipal archival data (including traffic levels, estimated waste generation, and air quality), and field observation checklists (covering waste bin availability, environmental hygiene, green space conditions, and physical fabric quality). These indicators were standardized on a five-point scale, allowing the environmental resilience status of different urban centers to be assessed.
After standardization, the criteria were weighted using a fuzzy weighting approach. A normalized decision matrix was then constructed, followed by the derivation of a weighted normalized matrix. Subsequently, the boundary approximation area was calculated using the MABAC technique, and the distances of each spatial element from this boundary were determined. Based on the resulting Q values, the spatial elements were ranked according to their influence on urban environmental resilience. The results indicated that commercial centers rank highest in terms of their impact on environmental resilience, followed by industrial centers and highly integrated road corridors. Public centers exhibited a moderate level of influence, while high-density residential areas, administrative centers, and tourism centers show relatively lower levels of environmental resilience.
Environmental impacts of the spatial structure of metropolitan Tabriz.
Several environmental consequences associated with the concentrated, monocentric spatial structure of Tabriz were identified.
Air pollution: One of the most prominent consequences of a centralized urban structure was increased air pollution, particularly in central areas. The findings indicated a rising trend in air pollution levels, largely driven by the rapid growth in motorized vehicle use. The concentration of service, commercial, and administrative activities in the urban core intensified daily traffic flows, leading to higher pollutant emissions. Areas that function as primary spatial cores exhibited the highest levels of air pollution, confirming the strong relationship between spatial concentration, traffic intensity, and environmental stress. Although significant residential populations were located in northern districts, the daytime concentration of activities in the city center resulted in greater congestion and air pollution in these central areas.
Distribution of particulate matter: Management of airborne particulate matter represented a key dimension of urban environmental resilience. Analysis of fine particulate matter concentrations indicated higher levels in western parts of the city, identifying these areas as major pollution zones. While southern and northern districts showed comparatively lower concentrations, the central area still exhibited elevated levels of airborne particulates, reflecting the cumulative effects of traffic, land-use concentration, and limited environmental capacity.
Environmental sustainability: Environmental sustainability constituted another important aspect of urban environmental resilience. Using data obtained from municipal environmental management sources, the sustainability status of different urban districts was assessed. The results showed notable spatial variation in environmental sustainability levels, with some districts exhibiting relatively high sustainability values, while others, particularly the central district fell into a condition of potential environmental instability. Overall, the metropolitan area of Tabriz demonstrated a moderate level of environmental sustainability, indicating that a substantial portion of the city is environmentally vulnerable and requires targeted interventions to enhance resilience.
Discussion
In this study, the relationship between the spatial structure of the city and the environmental resilience of Tabriz was examined. To this end, the interconnected processes of urban spatial elements were considered from a systems perspective. Since the city functions as a system composed of multiple components, any change in one spatial element can affect the performance of other elements and components of the system. Urban resilience, particularly urban environmental resilience, ensures the existence and survival of the urban system. In other words, the sustainability of urban systems is closely related to the quality of the natural urban environment. Although the urban environment is often considered a part of the urban system, in this study spatial elements, including the street network, activity–service centers, and population centers were regarded as the main components of the Tabriz urban system, and the relationships among these elements and the consequences of such interactions for urban environmental quality were examined.
In pursuing the research objective and adopting a systemic view of the functioning of Tabriz, the analysis of the city’s spatial structure yielded useful results. As shown, the various components forming the spatial structure of Tabriz, including the distribution of administrative, tourism, commercial, public, and industrial centers were not evenly distributed. The highest concentration of activity and service–recreational centers, except for industrial centers, was located in the city center, with lighter concentrations in areas surrounding the central zone. In other words, the spatial structure of Tabriz, based on the selected elements, was monocentric. It should be noted that while natural ecological conditions at the city scale may function relatively uniformly, the concentration of activity centers can disrupt such environmental conditions. In this way, the concentration of residents and their activities in a single part of the city can undermine the capacity and resilience of the urban environment. As the research findings indicated, air quality, noise pollution, and the amount of green space in the city center were lower than in peripheral areas. The results of this part of the study are consistent with the findings of Sobhani et al. (2019) and Esmailnejad et al. (2015).
The results also showed that urban environmental resilience is not limited to air pollution and particulate emissions. Increased environmental sensitivity to natural environmental factors, such as surface contamination from household and industrial waste disposal, soil and water erosion, reduction of green space due to increased building density, expansion of construction activities into deeper ground layers, and contamination of subsurface soil layers has contributed to a decline in urban environmental resilience. Field study results in metropolitan Tabriz indicate that buildings located along inner-city highways and households residing in the central areas were dissatisfied with noise pollution and air quality and tend to relocate away from the city center and farther from major streets. The fuzzy MABAC ranking also showed that commercial and industrial centers, with Q coefficients of 0.442 and 0.416 respectively, had high importance in urban environmental resilience. In other words, commercial and industrial centers exhibited greater sensitivity and higher potential for pollution compared to other parts of the city. Since the coefficients of these two parameters were positive, it can be concluded that increasing the volume and density of commercial and industrial land uses leads to an intensification of urban environmental problems and a reduction in resilience in these areas. High-density population centers, administrative centers, and tourism centers, due to their negative coefficients of −0.340, −0.233, and −0.347 respectively, had a lower impact on the environmental resilience of Tabriz. This part of the study is consistent with the findings of Niazi and Mohammadzadeh (2010).
Another set of findings revealed that the highest levels of air pollution and particulate matter are found in the central parts of the city. It was also determined that environmental resilience in central areas is lower than in peripheral zones. This reflects the vulnerable condition of the urban environment due to high traffic density and the excessive concentration of activities and fine-grained land parcels. While the spatial structure analysis showed higher levels of spatial integration and concentration of activity and service land uses in the city center, urban environmental assessment models also indicated that the city center experiences the highest levels of air pollution compared to other areas. Findings from other researchers further show that in the central part of the city, despite communication spaces occupying 21.6% of the urban fabric, they have failed to connect different parts of the city in a balanced and rational manner or to facilitate smoother movement. This area, by attracting more than 40% of total urban trips, experiences slower traffic flows, prolonged congestion, air and noise pollution, and traffic accidents more than any other part of the city. These results are consistent with the findings of Niazi and Mohammadzadeh (2010), Amadeh et al. (2018), and Karimi et al. (2020).
Conclusion
The conditions and quality of the urban environment in the central areas of Tabriz and their adjacent zones are characterized by instability and low resilience. The city’s spatial structure has led to an excessive concentration of trip-attracting land uses in this area, resulting in higher levels of traffic congestion and air pollution compared to other parts of the city.
Acknowledgments: The authors would like to express their gratitude to the staff of the Geographical Research journal.
Ethical Permission: There is nothing to report.
Conflict of Interest: This article is derived from the doctoral dissertation of Mehdi Shiripour, supervised by the second and third authors and advised by the fourth author.
Authors’ Contributions: Shiripour M (first author), Introduction Writer/Statistical Analyst (30%); Sasanpour F (second author), Introduction Writer/Methodologist (30%); Fassihi H (third author), Assistant Researcher (20%); Shamai A (fourth author), Assistant Researcher (20%)
Funding: The article was prepared independently and funded personally.
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