Extended Abstract
Introduction
The peripheral areas of cities are seriously affected by urban activities, and rapid urban population growth has resulted in urban reserve lands, farms, and surrounding gardens being converted into informal residential, industrial, service areas, and similar developments. Therefore, future urban growth and expansion - whether in terms of passages, land use, location of major urban facilities, or the establishment and implementation of proper methods for managing service affairs and service delivery to all residential areas - requires precise planning and implementation by urban managers in physical urban development. Controlling and directing physical urban expansion is also considered among urban management responsibilities (Smol et al., 2020: 692).
The policies and decisions of urban management institutions regarding land allocation and construction regulations are not without influence on urban expansion. In this regard, the development and presentation of urban planning and construction regulations for construction, acceptance of building plans, issuance of building permits, provision of basic urban infrastructure, housing provision and urban services (traffic, security, etc.), methods of urban land utilization, land price control, land and building taxation, determination of land use and building according to issued construction permits, issuance of supervision permits for supervising engineers, construction supervision, density sales, implementation of mass construction projects, and land subdivision methods are important in physical urban expansion. Therefore, a significant portion of cities' problems and challenges stem from the lack of sustainable management and proper planning of urban buffer zones (George et al., 2021: 1010). Spatial inequalities and polar development in Iran have caused population migration from villages to city peripheries, and the inefficiency of urban laws has pushed vulnerable groups to urban buffer zones (Sheikhi and Shabestari, 2018: 19).
Urban buffer zones represent an opportunity, but if managed and preserved without a comprehensive plan, they will become threats. In other words, the buffer zone is an inseparable space between the outer city line and urban areas, and achieving a sustainable urban environment requires establishing a fair balance between city rights and its buffer zone (Nedaei Tousi, 2021: 60).
An examination of various countries' experiences demonstrates that cities require peripheral and surrounding lands for their continued existence. In developed countries, this need has been managed and organized optimally with necessary preservation and protection, such that the potential of urban buffer zones is typically utilized for purposes like beneficial public use and the creation of green spaces, sports facilities, and recreational areas (Mihalic, 2020: 84).
Metropolitan regions have gradually emerged as economic, social, and physical-spatial phenomena in the country's settlement and territorial system over the past few decades. Currently, a significant portion of the country's population and activities are situated in the central city and surrounding areas and settlements, including within the spatial extent of the central city's buffer zone and other settlements located in metropolitan regions (Parishan et al., 2023: 84). Attention to, supervision of, and monitoring of metropolitan buffer zones like Tehran's can have a significant impact on achieving sustainable development and resolving urban and citizen problems while addressing the management challenges and development needs of each Tehran metropolitan region (Sarvar Rahim, 2019: 132). Therefore, awareness of the precise status of urban buffer zones beyond urban areas, examining changes, and controlling and monitoring urban buffer zones are essential requirements of urban protection management. Due to the lack of definitive boundaries, buffer zones, and serious control in the Tehran Metropolitan Area, overlapping and multiple responsibilities and parallel operations have led to encroachment and destruction of lands and unregulated construction, even by national and military institutions. This has resulted in the extensive destruction of landscapes and sustainable environmental potential and the creation of informal and unregulated settlements in the city's periphery, which, in addition to physical challenges, pose other serious spatial challenges, such as economic and social issues with influential parameters including unemployment, poverty, high population growth, and other vulnerabilities threatening this city.Therefore, it is necessary to seriously prevent the unregulated expansion and development of such detailed problems in the urban buffer zone through precise and appropriate planning. If negligence and oversight occur, the progression and increasing growth of challenges will result in the destruction of Tehran Metropolitan Area's buffer zone and the loss of respiratory capacity and urban reserve lands for the city's future sustainable development, with the consequences of buffer zone problems and issues seriously affecting Tehran Metropolitan Area's legal boundary as well.Tehran Metropolitan Area's buffer zone faces various challenges that are significantly more extensive than the problems within its boundaries, including encroachment on environmental capabilities, destruction of suitable agricultural lands, land and mountain grabbing, reduction of appropriate spaces, and expansion of informal and unregulated settlements, aggressive occupations, encroachment on service and urban reserve lands, issuance of case-by-case unregulated permits with isolated, profit-seeking, and commercial perspectives and daily income generation. These challenges cannot be ignored even for a moment. Accordingly, examining and understanding the upcoming challenges and providing necessary strategies to address existing problems and issues in the Tehran Metropolitan Area's southern buffer zone is of high
 
necessity and importance.Planning and management of urban buffer zones is a subject that has always been challenging and tension-generating in relationships between different governmental levels for various economic, political, and social reasons. Given the importance of the aforementioned issues, this research has focused on presenting a strategic pattern for sustainable management of the Tehran Metropolitan Area's buffer zone.
 
 
Methodology
The dominant approach in this research is developmental-applied, and the research method is descriptive, analytical, and survey-based. Required research information was collected through documentary, library, survey methods, and interviews with citizens and experts. The statistical population of the research includes 20 experts and specialists. In this research, the Fuzzy Delphi method was used to identify indicators. Subsequently, the area's strengths and weaknesses (internal strategic factors) and opportunities and threats (external strategic factors) were examined using the SWOT technique. In this section, the strategy matrix, which is based on comparing internal factors (weaknesses and strengths) and external factors (opportunities and threats) for the development of Tehran Metropolitan Area's southern buffer zone, was drawn in four types of strategies: aggressive (SO), contingency (ST), adaptive (WO), and defensive (WT), and strategies were formulated. Aggressive strategies indicate the most favorable situation and movement from any position in the SWOT matrix to an ideal situation, through which all positive points, advantages, and competencies can be used to maximize positions and opportunities. Within these strategies, strengths can be used to exploit external opportunities and maximize their utilization.
 
Results and Discussion
In this research, initially from among 26 identified factors, five factors - population growth and migration, urban policies and regulations, infrastructure, and public services, land use and urban planning, and environment and natural resources - were selected with expert assistance as factors for the strategic pattern of sustainable buffer zone management. Then, the factors in the strategic pattern of sustainable buffer zone management were prioritized using the fuzzy technique. Ranking results also showed that the land use and urban planning index has the closest proximity to the positive ideal solution, followed by population growth and migration in second place, infrastructure and public services in third place, and urban policies and regulations in last place.
 
 
Conclusion
Therefore, it can be claimed that this research's proposed model leads to a meaningful ranking of options, thus allowing relevant institutions to select higher-priority options for executive projects based on their degree of importance and prioritization. The model presented in this research has an appropriate systematization with defined stages and known inputs. This characteristic removes confusion for the employer, contractors, and relevant institutions regarding its implementation and provides assurance of appropriate output after work execution. Additionally, Fuzzy Delphi has enabled consideration of real and natural conditions governing the identification of factors affecting the strategic pattern of sustainable buffer zone management for application in facing destructive elements of the strategic pattern of sustainable buffer zone management, primarily characterized by uncertainty and ambiguity. This leads to more appropriate decisions that are closer to reality. It is recommended that factors affecting the strategic pattern of sustainable buffer zone management be reviewed at specific time intervals so that new indicators can be added, existing indicators can be improved, and old ones that are no longer applicable can be removed. Techniques such as Data Envelopment Analysis (DEA), VIKOR, LINMAP, etc., should be used for this purpose in similar research. These techniques can be applied in fuzzy or logical environments.