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Volume 38, Issue 2 (2023)
GeoRes 2023, 38(2): 203-210 |
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Received: 2023/03/29 | Accepted: 2023/05/6 | Published: 2023/06/18
Received: 2023/03/29 | Accepted: 2023/05/6 | Published: 2023/06/18
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Ravandoost M, Khademolhoseini A, Saberi H, Abbasi A. Physical Expansion Pattern of Bushehr City, Iran. GeoRes 2023; 38 (2) :203-210
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1- Department of Urban Planning, Faculty of Geography, Najafabad Branch, Islamic Azad University, Najafabad, Iran
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Introduction
The irregular pattern of urban growth, resulting from the random process of urbanization, is the most apparent impact of development on the urban system. As the trend of unrelenting urbanization and its subsequent consequences accelerate worldwide, particularly in the cities of developing countries such as India, this issue has increasingly drawn the attention of climatologists and urban geographers.
Urbanization is a socio-spatial process which, in addition to transforming social relations and increasing urban population, has dramatically altered the land use, size, and spatial extent of cities, thereby affecting the lives of people residing within and around them [Jaeger et al., 2010]. Urban growth, especially in developing countries, has caused extensive land-use and land-cover changes. Such excessive urban expansion has led to inefficient land use, severe traffic congestion, and a variety of environmental challenges [He et al., 2018]. It can be argued that urban growth is a key driver of landscape transformation in many parts of the world, particularly in developing nations. This phenomenon has become a primary cause of permanent landscape alteration and habitat loss, which directly affects the integrity of ecological systems and biodiversity [McGarigal et al., 2018].
Proper urban development is achieved only when land is utilized in accordance with its capabilities. Accordingly, identifying the potential of land prior to urban settlement and the allocation of uses and activities is of paramount importance. Otherwise, city development and the expansion of settlements may occur in ways constrained by natural and ecological limitations, leading to the discontinuity of activities and ultimately wasting much of the investment made [Mokhtari Hashi & Rahimi, 2016]. Thus, land and its constraints in urban areas have made the optimal utilization of land a crucial concern, especially when it serves as a key resource for settlement expansion [Sanders & Clark, 2010].
Urban physical development refers to the spatial expansion of the built-up areas of cities, which results in the conversion of other types of land use to urban and industrial ones. Therefore, analyzing land-use patterns and identifying spatial distributions of land use and land cover in a given region are essential [Karimi Firozjaei et al., 2018]. Urban physical expansion is a dynamic and continuous process through which the physical boundaries and built environment of a city increase both vertically and horizontally, in terms of quantity and quality. Today, unbalanced urban expansion is one of the major challenges in land-use management. Such expansion typically extends the city outward into its periphery.
Urban growth and development manifest in two forms: horizontal and vertical. Horizontal expansion occurs through the outward spread of city boundaries, often irregular and fragmented. Vertical growth, on the other hand, is characterized by densification and increased population concentration within the existing urban area [Jin et al., 2017].
The explosive pace of urbanization within limited urban areas necessitates both internal densification and external spatial expansion. Uncontrolled or irregular urban growth can lead to problems such as the destruction of open spaces, landscape transformation, environmental pollution, traffic congestion, infrastructure overload, and the conversion of rural and natural peripheries into raw materials for urban development, alongside other social and economic issues.
In Iran, most cities were originally established on fertile agricultural lands for cultivation purposes or located within high-quality farmlands. Over time, with the expansion of villages into towns and then cities, these fertile lands have been consumed by urbanization, forcing agricultural activities to shift onto less suitable lands. To address such challenges, continuous monitoring of urban growth patterns, in terms of both type and magnitude of change over time, is essential for effective urban planning [Bastin et al., 2018].
Various models of urban growth and morphology have been identified, including concentric zones, sectoral growth (Hoyt’s theory), circular models, star-shaped expansion, generalized growth, and multiple nuclei. Ernest Burgess introduced the concentric zone model, in which urban development radiates outward from the central area, forming successive concentric zones. This begins with the central business district, surrounded by zones undergoing transformation such as light industries, administrative buildings, or smaller housing units. These transitional areas often attract new migrants. Further out, workers’ residences, old housing units, and commuter zones appear, eventually blending into open spaces or suburban settlements [Shie, 2016].
According to Hoyt’s sector theory, urban growth tends to radiate outward in wedge-shaped sectors rather than concentric circles. Higher-rent residential areas typically expand toward open spaces, away from natural or environmental constraints. The relocation of administrative and commercial buildings fosters the development of expensive residential units. Luxury housing clusters near commercial districts, while industrial activities tend to follow transport routes and water sources, expanding linearly. Accessibility to radial routes from the city center significantly determines urban land values [Shie, 2016; He et al., 2023].
The circular city model emphasizes that urban structure is not static but evolves through both outward expansion and inward densification. With population growth and central city pressures, urban ecological processes such as segregation, invasion, succession, and displacement spread into surrounding areas. Natural barriers—such as steep slopes, hills, and mountains, can restrict growth, increasing development costs and redirecting expansion patterns. Similarly, transport networks such as highways, roads, and railways are shaped by both natural and spatial constraints.
Dickinson’s general urban model identifies four zones: (a) the central ring, comprising the city’s historic core, wholesale and retail trade centers, administrative offices, and some residential units; (b) the middle zone, characterized by dense housing and small industries; (c) the outer zone, primarily residential with open spaces and public parks; and (d) the city fringe, extending beyond administrative boundaries into rural hinterlands. As cities expand, residential zones advance outward, while new industries emerge along key transport routes and around satellite towns and villages [Shie, 2016; Hataminezhad et al., 2016].
In the multiple nuclei theory, small cities may have only one core, whereas larger modern cities often contain multiple nuclei, usually formed at transport intersections. Commercial activities cluster around railway stations, airports, and major road intersections. Harris and Ullman argued that land use in large cities cannot be explained by a single nucleus; instead, urban activities tend to cluster around multiple specialized nodes. Some nuclei are historically rooted, such as London, which from its inception had two distinct cores “the City,” a financial hub, and Westminster, the political center. Others emerge over time due to functional specialization or relocation of institutions.
Of all urban morphology models, the multiple nuclei model best explains the structure of large cities, whereas smaller towns typically retain a single, central nucleus. In metropolitan areas, new nuclei emerge as a result of spatial growth, accessibility, and environmental factors, creating polycentric urban systems [Shokouei, 2003; Sajadzadeh & Rahmani, 2014].
The city of Bushehr, located on the northern coast of the Persian Gulf, has experienced rapid and extensive growth in recent decades. Its increasing population, coupled with infrastructure inadequacies, has significantly altered the city’s spatial form and urban fabric. Its coastal location and port- and oil-based economy have also undergone profound transformations. Consequently, Bushehr’s land use patterns have become unbalanced.
On one hand, outward and horizontal expansion has resulted in excessive degradation of old urban areas, the loss of valuable surrounding lands, and encroachment on natural spaces. On the other hand, the city’s geopolitical and economic significance, coupled with steady population growth, has created a shortage of land for expansion. Physical development is constrained by the sea to the north and west, a nuclear power plant and its safety buffer to the south, and marshy lands and seasonal waterways to the east [Heidari, 2014].
Additionally, vast military bases located in the northern and southern sectors of the city limit urban land availability, preventing infill development. These constraints, together with decaying inner-city fabrics, representing the city’s historical core, have not attracted population but rather repelled it, undermining possibilities for inner-city regeneration.
Alongside these structural challenges, Bushehr continues to attract large numbers of migrants as the provincial capital, further intensifying pressures on its limited land resources. Against this backdrop, the present study seeks to identify the limiting factors and determinants shaping the physical expansion patterns of Bushehr city.
Methodology
This mixed-method study was conducted in 2022 in the city of Bushehr and its surrounding areas in two main phases.
In the first phase, the change in the spatial extent of urban and suburban areas in Bushehr between 1985 and 2023 was analyzed using remote sensing techniques. For this purpose, satellite images from TM (1984–1999) and LANDSAT 8–9 OLI/TIRS were employed. Appropriate band composites were generated for each satellite image to facilitate visual interpretation. Subsequently, slope files of the urban boundaries for the years 1985 and 2023 were prepared using digital tools in the ArcMap environment for comparative analysis of urban development. After identifying the extent of urban growth, the structural patterns of development were determined and analyzed with reference to existing theories in this field. Remote sensing techniques in ENVI 5.6 software were used to examine the expansion of Bushehr and its physical development patterns.
In the second phase, the most important advantages of Bushehr’s polycentric growth were examined. Key components in this regard were identified through a review of existing theories and previous studies. These components were then incorporated into a questionnaire consisting of 30 items. The initial questionnaire was reviewed in two rounds by a panel of 30 experts specialized in relevant fields, during which unsuitable items were removed.
For the quantitative section, following the development of the second version of the questionnaire, content validity was assessed to ensure the necessity and appropriateness of the selected items. Content validity ratio (CVR) and content validity index (CVI) were calculated quantitatively using the feedback from the same panel of 30 experts. For CVI assessment, experts were asked to evaluate each item in terms of relevance, simplicity, and clarity using a four-point Likert scale (1: not relevant, 2: somewhat relevant, 3: relevant, 4: highly relevant). The questionnaire’s CVR and CVI values were confirmed with scores above 60%.
The validated questionnaire was then distributed among 250 experts in the fields of urban management and planning in Bushehr. The sample size was determined using Cochran’s formula, and the participants were selected through simple random sampling. The collected data were analyzed using the one-sample T-test and the VIKOR method [Dolatkhah et al., 2023].
Findings
The horizontal expansion of Bushehr city has developed distinctly in several nuclei. The physical expansion structure of this city has been shaped according to the multiple nuclei model (based on Ullman and Harris’s theory). The main nuclei of Bushehr’s expansion are located in the northern, western, eastern, and southernmost parts of the city. The extent of expansion and land-use changes in urban and suburban areas during 1984 and 2022 are presented. Accordingly, the largest physical expansion occurred in the eastern nucleus (Nucleus 3).
The smallest extent of marginal expansion was observed in the first nucleus. Nevertheless, the physical expansion of Bushehr city was significant across all nuclei.
The questionnaire-derived components included three main dimensions: environmental, social, and economic, comprising a total of 16 effective sub-dimensions. Based on analytical findings from the one-sample t-test, the conditions of environmental (3.57), social (3.04), and economic (3.95) indicators were reported as moderate. Compared to the theoretical median (3), they were positioned at a relatively higher level.
Among the environmental dimensions, damage to green spaces and preservation of historical buildings had the highest and lowest mean T-values, respectively.
Among the social dimensions, improvement of community health and well-being and equitable distribution of urban services had the highest and lowest mean T-values, respectively.
Among the economic dimensions, functional diversity and multiplicity of urban centers and distribution of opportunities and activity centers within a balanced structure had the highest and lowest mean T-values, respectively.
The evaluation of the impacts of Bushehr city’s multi-nuclei expansion using the VIKOR weighting method indicated that the greatest significance within the environmental dimension was related to damage to green spaces (weight = 0.81).
In the environmental dimension, the highest weights were assigned to damage to green spaces and increase in energy efficiency; in the social dimension, to preservation of unique cultural industries and social cohesion with increased local participation; and in the economic dimension, to tourism development through environmental diversity of centers and functional diversity with multiplicity of urban centers.
The lowest weighted impacts of Bushehr’s physical expansion were observed in preservation of historical buildings (environmental), reduction of public service development costs (economic), and equitable distribution of urban services (social).
Discussion
Today, population growth and urbanization, and consequently the physical expansion of cities, are among the most significant concerns of geographers and urban planners. The growth and expansion of cities, manifested in different patterns of spatial development, have always been associated with economic dimensions, accessibility to services, and the quality of the urban environment. Over the past decades, Iranian cities, similar to many cities in the developing world, have undergone remarkable transformations. Among these, the rapid population growth and widespread urban sprawl in most cities of the country can be attributed to the lack of proper planning based on comprehensive knowledge of urban lands. Although urban expansion is primarily driven by economic and demographic factors, it exerts a profound influence on multiple dimensions [Kumar Mallick et al., 2023].
Initially, Bushehr experienced slow physical growth due to its organic development. However, with the rise of urbanization, high natural growth rates, rural-to-urban migration, and oil revenues in the urban economy, the city acquired an exogenous nature. Consequently, its physical growth was driven not by actual demand but by land speculation, resulting in dispersed and horizontal development.
According to the multiple nuclei theory, urban nuclei are not created at the initial stages of city formation but emerge over time with distinct functions. The physical development pattern of Bushehr Port conforms to this process.
The findings of this study reveal that in the environmental dimension, preservation of historical buildings and waste collection and urban cleaning services received the lowest scores. In fact, as urban nuclei expanded and residential and commercial land uses spread, especially with the increased allocation of peripheral lands for urban construction, the likelihood of damage to historical buildings and encroachment on their protected zones intensified, highlighting the need for greater attention in this regard. Likewise, the expansion of urban nuclei tends to reduce the efficiency of urban cleaning services and public hygiene. In a multi-nuclei pattern, the spatial extent of built-up areas increases, which may lead to delays in service provision. Furthermore, damage to green space ecosystems and trees emerges as a critical environmental concern that necessitates preventive measures amid Bushehr’s multi-nuclei expansion. In this regard, the siting of facilities and allocation of land uses should be determined with minimum damage to green spaces in mind.
Compact urban development can potentially shorten travel distances, thereby facilitating transportation, increasing the walkable catchment area, and reducing dependence on private cars [Stevenson et al., 2016; Bereitschaft & Debbage, 2013]. In such contexts, populations tend to concentrate in existing areas, fostering the establishment of more supportive facilities (e.g., healthcare, educational, and recreational services) [Bardhan et al., 2015]. By contrast, under a multi-nuclei urban form, the quality of accessibility declines due to the wider spatial distribution of service areas. Moreover, transportation costs may rise because of increased travel distances. The results of this study emphasized the importance of improving service delivery and enhancing the quality of urban transportation within the social dimension, consistent with the findings of Cengiz et al. [2022].
Residents in dispersed and peripheral urban areas generally enjoy more space and lower land costs, which allows them to save on living expenses. Due to lower building density in Bushehr’s dispersed urban areas, air pollution, heat island effects, and temperature inversion phenomena occur less frequently compared to compact urban zones. Nevertheless, the dispersion of urban nuclei increases the cost of road construction, transportation, healthcare, education, and the provision of utilities such as water and electricity. The uneven distribution of these services, combined with the concentration of services in specific areas and reduced public transportation, leads to greater reliance on private vehicles. This, in turn, generates traffic congestion, particularly during peak hours, which can disrupt transportation efficiency. As a result, local access to urban services may become problematic. Increased traffic further contributes to higher levels of air and noise pollution, adversely impacting the environment. These findings are in line with those of Brueckner [2007], Cervero [2010], and Hadjidemetriou et al. [2022].
Nevertheless, despite the multi-nuclei expansion of Bushehr’s urban structure, the creation of additional nuclei, especially in the northern parts of the city and around Enghelab Square, historically significant for the local population, can help reduce the concentration of commercial-service buildings and population density. Clearly, the future development of the city and its growing population will require the establishment of a secondary urban center to ensure that future commercial, administrative, and service needs of the citizens are adequately met.
Conclusion
The urban structure of Bushehr has developed in a polycentric form with four main nuclei. The most significant impacts of this polycentric development can be summarized across the economic, social, and environmental dimensions. Particular attention is required to the indicators of green space degradation and energy efficiency improvement in the environmental dimension; preservation of unique cultural industries and promotion of social cohesion and local participation in the social dimension; and the development of tourism industries based on environmental diversity along with the functional diversity and multiplicity of urban centers in the economic dimension. Addressing these priorities is essential for tackling the challenges of Bushehr’s polycentric growth and ensuring more effective urban management.
The irregular pattern of urban growth, resulting from the random process of urbanization, is the most apparent impact of development on the urban system. As the trend of unrelenting urbanization and its subsequent consequences accelerate worldwide, particularly in the cities of developing countries such as India, this issue has increasingly drawn the attention of climatologists and urban geographers.
Urbanization is a socio-spatial process which, in addition to transforming social relations and increasing urban population, has dramatically altered the land use, size, and spatial extent of cities, thereby affecting the lives of people residing within and around them [Jaeger et al., 2010]. Urban growth, especially in developing countries, has caused extensive land-use and land-cover changes. Such excessive urban expansion has led to inefficient land use, severe traffic congestion, and a variety of environmental challenges [He et al., 2018]. It can be argued that urban growth is a key driver of landscape transformation in many parts of the world, particularly in developing nations. This phenomenon has become a primary cause of permanent landscape alteration and habitat loss, which directly affects the integrity of ecological systems and biodiversity [McGarigal et al., 2018].
Proper urban development is achieved only when land is utilized in accordance with its capabilities. Accordingly, identifying the potential of land prior to urban settlement and the allocation of uses and activities is of paramount importance. Otherwise, city development and the expansion of settlements may occur in ways constrained by natural and ecological limitations, leading to the discontinuity of activities and ultimately wasting much of the investment made [Mokhtari Hashi & Rahimi, 2016]. Thus, land and its constraints in urban areas have made the optimal utilization of land a crucial concern, especially when it serves as a key resource for settlement expansion [Sanders & Clark, 2010].
Urban physical development refers to the spatial expansion of the built-up areas of cities, which results in the conversion of other types of land use to urban and industrial ones. Therefore, analyzing land-use patterns and identifying spatial distributions of land use and land cover in a given region are essential [Karimi Firozjaei et al., 2018]. Urban physical expansion is a dynamic and continuous process through which the physical boundaries and built environment of a city increase both vertically and horizontally, in terms of quantity and quality. Today, unbalanced urban expansion is one of the major challenges in land-use management. Such expansion typically extends the city outward into its periphery.
Urban growth and development manifest in two forms: horizontal and vertical. Horizontal expansion occurs through the outward spread of city boundaries, often irregular and fragmented. Vertical growth, on the other hand, is characterized by densification and increased population concentration within the existing urban area [Jin et al., 2017].
The explosive pace of urbanization within limited urban areas necessitates both internal densification and external spatial expansion. Uncontrolled or irregular urban growth can lead to problems such as the destruction of open spaces, landscape transformation, environmental pollution, traffic congestion, infrastructure overload, and the conversion of rural and natural peripheries into raw materials for urban development, alongside other social and economic issues.
In Iran, most cities were originally established on fertile agricultural lands for cultivation purposes or located within high-quality farmlands. Over time, with the expansion of villages into towns and then cities, these fertile lands have been consumed by urbanization, forcing agricultural activities to shift onto less suitable lands. To address such challenges, continuous monitoring of urban growth patterns, in terms of both type and magnitude of change over time, is essential for effective urban planning [Bastin et al., 2018].
Various models of urban growth and morphology have been identified, including concentric zones, sectoral growth (Hoyt’s theory), circular models, star-shaped expansion, generalized growth, and multiple nuclei. Ernest Burgess introduced the concentric zone model, in which urban development radiates outward from the central area, forming successive concentric zones. This begins with the central business district, surrounded by zones undergoing transformation such as light industries, administrative buildings, or smaller housing units. These transitional areas often attract new migrants. Further out, workers’ residences, old housing units, and commuter zones appear, eventually blending into open spaces or suburban settlements [Shie, 2016].
According to Hoyt’s sector theory, urban growth tends to radiate outward in wedge-shaped sectors rather than concentric circles. Higher-rent residential areas typically expand toward open spaces, away from natural or environmental constraints. The relocation of administrative and commercial buildings fosters the development of expensive residential units. Luxury housing clusters near commercial districts, while industrial activities tend to follow transport routes and water sources, expanding linearly. Accessibility to radial routes from the city center significantly determines urban land values [Shie, 2016; He et al., 2023].
The circular city model emphasizes that urban structure is not static but evolves through both outward expansion and inward densification. With population growth and central city pressures, urban ecological processes such as segregation, invasion, succession, and displacement spread into surrounding areas. Natural barriers—such as steep slopes, hills, and mountains, can restrict growth, increasing development costs and redirecting expansion patterns. Similarly, transport networks such as highways, roads, and railways are shaped by both natural and spatial constraints.
Dickinson’s general urban model identifies four zones: (a) the central ring, comprising the city’s historic core, wholesale and retail trade centers, administrative offices, and some residential units; (b) the middle zone, characterized by dense housing and small industries; (c) the outer zone, primarily residential with open spaces and public parks; and (d) the city fringe, extending beyond administrative boundaries into rural hinterlands. As cities expand, residential zones advance outward, while new industries emerge along key transport routes and around satellite towns and villages [Shie, 2016; Hataminezhad et al., 2016].
In the multiple nuclei theory, small cities may have only one core, whereas larger modern cities often contain multiple nuclei, usually formed at transport intersections. Commercial activities cluster around railway stations, airports, and major road intersections. Harris and Ullman argued that land use in large cities cannot be explained by a single nucleus; instead, urban activities tend to cluster around multiple specialized nodes. Some nuclei are historically rooted, such as London, which from its inception had two distinct cores “the City,” a financial hub, and Westminster, the political center. Others emerge over time due to functional specialization or relocation of institutions.
Of all urban morphology models, the multiple nuclei model best explains the structure of large cities, whereas smaller towns typically retain a single, central nucleus. In metropolitan areas, new nuclei emerge as a result of spatial growth, accessibility, and environmental factors, creating polycentric urban systems [Shokouei, 2003; Sajadzadeh & Rahmani, 2014].
The city of Bushehr, located on the northern coast of the Persian Gulf, has experienced rapid and extensive growth in recent decades. Its increasing population, coupled with infrastructure inadequacies, has significantly altered the city’s spatial form and urban fabric. Its coastal location and port- and oil-based economy have also undergone profound transformations. Consequently, Bushehr’s land use patterns have become unbalanced.
On one hand, outward and horizontal expansion has resulted in excessive degradation of old urban areas, the loss of valuable surrounding lands, and encroachment on natural spaces. On the other hand, the city’s geopolitical and economic significance, coupled with steady population growth, has created a shortage of land for expansion. Physical development is constrained by the sea to the north and west, a nuclear power plant and its safety buffer to the south, and marshy lands and seasonal waterways to the east [Heidari, 2014].
Additionally, vast military bases located in the northern and southern sectors of the city limit urban land availability, preventing infill development. These constraints, together with decaying inner-city fabrics, representing the city’s historical core, have not attracted population but rather repelled it, undermining possibilities for inner-city regeneration.
Alongside these structural challenges, Bushehr continues to attract large numbers of migrants as the provincial capital, further intensifying pressures on its limited land resources. Against this backdrop, the present study seeks to identify the limiting factors and determinants shaping the physical expansion patterns of Bushehr city.
Methodology
This mixed-method study was conducted in 2022 in the city of Bushehr and its surrounding areas in two main phases.
In the first phase, the change in the spatial extent of urban and suburban areas in Bushehr between 1985 and 2023 was analyzed using remote sensing techniques. For this purpose, satellite images from TM (1984–1999) and LANDSAT 8–9 OLI/TIRS were employed. Appropriate band composites were generated for each satellite image to facilitate visual interpretation. Subsequently, slope files of the urban boundaries for the years 1985 and 2023 were prepared using digital tools in the ArcMap environment for comparative analysis of urban development. After identifying the extent of urban growth, the structural patterns of development were determined and analyzed with reference to existing theories in this field. Remote sensing techniques in ENVI 5.6 software were used to examine the expansion of Bushehr and its physical development patterns.
In the second phase, the most important advantages of Bushehr’s polycentric growth were examined. Key components in this regard were identified through a review of existing theories and previous studies. These components were then incorporated into a questionnaire consisting of 30 items. The initial questionnaire was reviewed in two rounds by a panel of 30 experts specialized in relevant fields, during which unsuitable items were removed.
For the quantitative section, following the development of the second version of the questionnaire, content validity was assessed to ensure the necessity and appropriateness of the selected items. Content validity ratio (CVR) and content validity index (CVI) were calculated quantitatively using the feedback from the same panel of 30 experts. For CVI assessment, experts were asked to evaluate each item in terms of relevance, simplicity, and clarity using a four-point Likert scale (1: not relevant, 2: somewhat relevant, 3: relevant, 4: highly relevant). The questionnaire’s CVR and CVI values were confirmed with scores above 60%.
The validated questionnaire was then distributed among 250 experts in the fields of urban management and planning in Bushehr. The sample size was determined using Cochran’s formula, and the participants were selected through simple random sampling. The collected data were analyzed using the one-sample T-test and the VIKOR method [Dolatkhah et al., 2023].
Findings
The horizontal expansion of Bushehr city has developed distinctly in several nuclei. The physical expansion structure of this city has been shaped according to the multiple nuclei model (based on Ullman and Harris’s theory). The main nuclei of Bushehr’s expansion are located in the northern, western, eastern, and southernmost parts of the city. The extent of expansion and land-use changes in urban and suburban areas during 1984 and 2022 are presented. Accordingly, the largest physical expansion occurred in the eastern nucleus (Nucleus 3).
The smallest extent of marginal expansion was observed in the first nucleus. Nevertheless, the physical expansion of Bushehr city was significant across all nuclei.
The questionnaire-derived components included three main dimensions: environmental, social, and economic, comprising a total of 16 effective sub-dimensions. Based on analytical findings from the one-sample t-test, the conditions of environmental (3.57), social (3.04), and economic (3.95) indicators were reported as moderate. Compared to the theoretical median (3), they were positioned at a relatively higher level.
Among the environmental dimensions, damage to green spaces and preservation of historical buildings had the highest and lowest mean T-values, respectively.
Among the social dimensions, improvement of community health and well-being and equitable distribution of urban services had the highest and lowest mean T-values, respectively.
Among the economic dimensions, functional diversity and multiplicity of urban centers and distribution of opportunities and activity centers within a balanced structure had the highest and lowest mean T-values, respectively.
The evaluation of the impacts of Bushehr city’s multi-nuclei expansion using the VIKOR weighting method indicated that the greatest significance within the environmental dimension was related to damage to green spaces (weight = 0.81).
In the environmental dimension, the highest weights were assigned to damage to green spaces and increase in energy efficiency; in the social dimension, to preservation of unique cultural industries and social cohesion with increased local participation; and in the economic dimension, to tourism development through environmental diversity of centers and functional diversity with multiplicity of urban centers.
The lowest weighted impacts of Bushehr’s physical expansion were observed in preservation of historical buildings (environmental), reduction of public service development costs (economic), and equitable distribution of urban services (social).
Discussion
Today, population growth and urbanization, and consequently the physical expansion of cities, are among the most significant concerns of geographers and urban planners. The growth and expansion of cities, manifested in different patterns of spatial development, have always been associated with economic dimensions, accessibility to services, and the quality of the urban environment. Over the past decades, Iranian cities, similar to many cities in the developing world, have undergone remarkable transformations. Among these, the rapid population growth and widespread urban sprawl in most cities of the country can be attributed to the lack of proper planning based on comprehensive knowledge of urban lands. Although urban expansion is primarily driven by economic and demographic factors, it exerts a profound influence on multiple dimensions [Kumar Mallick et al., 2023].
Initially, Bushehr experienced slow physical growth due to its organic development. However, with the rise of urbanization, high natural growth rates, rural-to-urban migration, and oil revenues in the urban economy, the city acquired an exogenous nature. Consequently, its physical growth was driven not by actual demand but by land speculation, resulting in dispersed and horizontal development.
According to the multiple nuclei theory, urban nuclei are not created at the initial stages of city formation but emerge over time with distinct functions. The physical development pattern of Bushehr Port conforms to this process.
The findings of this study reveal that in the environmental dimension, preservation of historical buildings and waste collection and urban cleaning services received the lowest scores. In fact, as urban nuclei expanded and residential and commercial land uses spread, especially with the increased allocation of peripheral lands for urban construction, the likelihood of damage to historical buildings and encroachment on their protected zones intensified, highlighting the need for greater attention in this regard. Likewise, the expansion of urban nuclei tends to reduce the efficiency of urban cleaning services and public hygiene. In a multi-nuclei pattern, the spatial extent of built-up areas increases, which may lead to delays in service provision. Furthermore, damage to green space ecosystems and trees emerges as a critical environmental concern that necessitates preventive measures amid Bushehr’s multi-nuclei expansion. In this regard, the siting of facilities and allocation of land uses should be determined with minimum damage to green spaces in mind.
Compact urban development can potentially shorten travel distances, thereby facilitating transportation, increasing the walkable catchment area, and reducing dependence on private cars [Stevenson et al., 2016; Bereitschaft & Debbage, 2013]. In such contexts, populations tend to concentrate in existing areas, fostering the establishment of more supportive facilities (e.g., healthcare, educational, and recreational services) [Bardhan et al., 2015]. By contrast, under a multi-nuclei urban form, the quality of accessibility declines due to the wider spatial distribution of service areas. Moreover, transportation costs may rise because of increased travel distances. The results of this study emphasized the importance of improving service delivery and enhancing the quality of urban transportation within the social dimension, consistent with the findings of Cengiz et al. [2022].
Residents in dispersed and peripheral urban areas generally enjoy more space and lower land costs, which allows them to save on living expenses. Due to lower building density in Bushehr’s dispersed urban areas, air pollution, heat island effects, and temperature inversion phenomena occur less frequently compared to compact urban zones. Nevertheless, the dispersion of urban nuclei increases the cost of road construction, transportation, healthcare, education, and the provision of utilities such as water and electricity. The uneven distribution of these services, combined with the concentration of services in specific areas and reduced public transportation, leads to greater reliance on private vehicles. This, in turn, generates traffic congestion, particularly during peak hours, which can disrupt transportation efficiency. As a result, local access to urban services may become problematic. Increased traffic further contributes to higher levels of air and noise pollution, adversely impacting the environment. These findings are in line with those of Brueckner [2007], Cervero [2010], and Hadjidemetriou et al. [2022].
Nevertheless, despite the multi-nuclei expansion of Bushehr’s urban structure, the creation of additional nuclei, especially in the northern parts of the city and around Enghelab Square, historically significant for the local population, can help reduce the concentration of commercial-service buildings and population density. Clearly, the future development of the city and its growing population will require the establishment of a secondary urban center to ensure that future commercial, administrative, and service needs of the citizens are adequately met.
Conclusion
The urban structure of Bushehr has developed in a polycentric form with four main nuclei. The most significant impacts of this polycentric development can be summarized across the economic, social, and environmental dimensions. Particular attention is required to the indicators of green space degradation and energy efficiency improvement in the environmental dimension; preservation of unique cultural industries and promotion of social cohesion and local participation in the social dimension; and the development of tourism industries based on environmental diversity along with the functional diversity and multiplicity of urban centers in the economic dimension. Addressing these priorities is essential for tackling the challenges of Bushehr’s polycentric growth and ensuring more effective urban management.
Keywords:
References
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