تعادل بخشی جمعیت در ساختار فضایی شهر یزد (مقاله علمی وزارت علوم)
درجه علمی: نشریه علمی (وزارت علوم)
آرشیو
چکیده
شهر یزد به عنوان یکی از شهرهای بزرگ ایران در دهه های اخیر به عدم تعادل در نظام فضایی و جمعیتی خود مبتلا گشته است و محصول این روند در دهه های اخیر تا به امروز موجب مشکلاتی همچون توسعه افقی و نامتوازن شهر یزد شده است. هدف این پژوهش شناسایی مؤلفه ها و پیشران های مؤثر بر نامتعادل شدن توزیع فضایی جمعیت و بررسی ارتباط آن با ساختار فضایی شهر یزد برای ایجاد تعادل فضایی جمعیت و نظام شهری و روستایی در پهنه سرزمینی شهر یزد است. روش پژوهش ا نظر هدف کاربردی و به دلیل به کارگیری روش های کیفی و کمّی در زمره پژوهش های ترکیبی قرار دارد. در این پژوهش از روش آینده پژوهی برای شناسایی پیشران های مؤثر بر تعادل جمعیت و از الگوریتم ژنتیک برای مدل سازی و بهینه سازی توزیع جمعیت استفاده شده است. یافته ها بیانگر آن است که پیشران های توزیع فضایی کانون های خدماتی و عملکردی، توزیع فضایی مراکز کار و فعالیت و الگوی ساختار فضایی با تأکید بر مقیاس عملکردی مناطق و شهر به ترتیب عامل اصلی جذب جمعیت و مؤثر بر الگوی توزیع فضایی و جمعیتی در شهر یزد هستند. نتایج پژوهش حاکی ازآن است که 1. توزیع فضایی اراضی بایر رابطه معکوسی با توزیع فضایی مراکز خدماتی-عملکردی و کانون های فعالیتی دارد و هرجا تمرکز کمتری از مراکز مذکور وجود داشته باشد، نسبت سهم اراضی بایر به مساحت محدوده مدنظر بیشتر است؛ 2. بدون استفاده ماندن زمین ها و کاهش پویایی فضایی در برخی مناطق شهری (منطقه C و B) و 3. پراکنش ناموزون فضایی مراکز خدماتی-عملکردی و کانون های فعالیتی و توسعه افقی سبب عدم تعادل در توزیع فضایی جمعیت شهر یزد شده است.Balancing the Population in the Spatial Structure of Yazd Metropolitan Area
In recent decades, Yazd, one of Iran's major cities, has encountered spatial and demographic imbalances. This trend has led to challenges, such as uneven and horizontal urban expansion. The aim of this study was to identify the key components and driving forces behind the spatial imbalance in population distribution and explore their relationship with the spatial structure of Yazd. The ultimate goal was to foster a balanced spatial distribution of the population and an integrated urban-rural system within Yazd territory. Methodologically, this research was applied in nature and utilized a mixed-methods approach, combining both qualitative and quantitative techniques. Foresight methods were employed to identify the driving forces affecting population balance, while genetic algorithms were used to model and optimize population distribution. The findings indicated that the spatial distribution of service and functional centers, employment and activity hubs, and the overall spatial structural pattern—particularly at the functional scale of urban areas—were the primary determinants influencing population attraction and the patterns of spatial and demographic distribution in Yazd. The results revealed: 1) an inverse relationship between the spatial distribution of barren lands and that of service-functional centers and activity hubs; areas with fewer such centers tended to have a higher proportion of barren land; 2) underutilization of land and diminished spatial dynamism in certain urban zones (specifically Zones B and C); 3) uneven spatial distribution of service-functional centers and activity hubs combined with horizontal urban growth had contributed to the spatial imbalance in the population distribution of Yazd. Keywords : Balancing, Population Density, Spatial Structure, Genetic Algorithm, Spatial Distribution, Yazd. Introduction Over the past two decades, urban growth in developed countries has been characterized by the emergence of diverse suburban activity centers. These centers have directly competed with traditional urban areas by decentralizing populations and activities, thereby transforming the spatial structure of contemporary urban environments and fostering more dispersed, polycentric spatial patterns. Research on population spatial structures indicates that the distribution of metropolitan populations is less balanced in developing countries compared to their developed counterparts. This imbalance is particularly evident in the population distribution systems of developing nations, such as Iran, over recent decades. Such imbalances have intensified rural-to-urban migration and further entrenched centralization rather than promoting equilibrium. The extreme concentration of job opportunities driven by centralized economic development has led to resource and capacity accumulation in certain areas while leaving others with low population and development levels. To achieve a more balanced spatial distribution of population within the rural and urban systems of Yazd Metropolis, it is crucial to identify the driving factors that have contributed to these disparities. This involves examining the relationships between these drivers and the city’s spatial structure, as well as assessing the potential for equitable access to services, facilities, and social and economic infrastructure. Consequently, this study first investigated the factors influencing changes in the spatial structure of population to understand the reasons behind the imbalanced population density in both rural and urban areas of the metropolitan region of Yazd. This analysis employed foresight methods. Following this, artificial intelligence was utilized to develop optimal strategies for the redistribution and resettlement of the population in the identified suitable areas. Materials & Methods This study was applied in nature and employed a mixed-methods approach, incorporating both qualitative and quantitative data. The research was conducted in two stages. In the first stage, a futuristic approach was adopted. After reviewing the relevant theoretical foundations and upstream documents, an initial conceptual model was developed. In-depth structured interviews were then conducted with a sample of selected individuals to assess the validity of the proposed model and identify the driving forces influencing the spatial structure of the population in the metropolitan area of Yazd. In the second stage, the factors with the most significant impact on population changes within the spatial structure of Yazd were identified. The most likely scenario for optimal conditions was modeled using genetic algorithms. This modeling aimed to determine the ideal balanced population density for each neighborhood, district, and area of the city by redistributing activity and service centers within these confines. The study area was the city of Yazd, Iran, which has a population of over 656,474 people according to the 2016 general census. As the most populous city in Yazd Province, Yazd is considered one of the largest cities in Iran with 611,466 residents in urban areas and 45,007 in rural areas. Yazd City comprises two central districts (Yazd City-Hamidia and Shahidieh) and Zarch District, which includes two rural districts: Fajr and Fahraj, while Zarch District encompasses Allahabad and Mohammadabad. Research Findings The interviews conducted in this study were analyzed to identify the factors influencing changes in the spatial structure of the population in the metropolitan area of Yazd. This analysis involved coding the responses using key words and phrases in MAXQDA software. Due to the inadequate per capita value for each service and activity center, the employed genetic algorithm was able to reduce the discrepancies in these values, thereby balancing the distribution of these centers. To address the per capita shortages, barren and brownfield lands in each area were utilized. At this stage of the research, the most optimal scenario (Scenario 3) was modeled by focusing on the key factors of "spatial distribution of service and activity centers" and "spatial distribution of workplaces". This modeling involved revising the per capita distribution of these centers at the neighborhood, district, and area scales within the studied urban region. The genetic algorithm was employed to enhance population balance with the optimization process following a bottom-up approach, starting from neighborhoods and progressing to broader areas of the city. Overall, the genetic algorithm effectively minimized the differences in per capita values, contributing to a more equitable distribution of service and activity centers. Discussion of Results & Conclusion The findings revealed that the primary drivers of population attraction and the determinants of spatial and demographic distribution patterns in Yazd were: (1) spatial distribution of service and functional centers, (2) distribution of employment and activity hubs, and (3) overall spatial structure, particularly at the functional scale of urban regions and the city as a whole. As of 1996 (1375 in the Iranian calendar), most of these centers were concentrated in a single nucleus within Zones A2 (currently 136.5 hectares) and A1 (currently 109.88 hectares), reflecting the mono-centric and insular spatial structure of Yazd. Between 1996 and 2016 (1375 to 1395), some centers relocated to Zone A3 (currently 84.61 hectares) and new centers also showed a tendency to concentrate in this area. The polarity of Yazd City across the three regions (A1, A2, A3) was significantly higher compared to Areas B and C, resulting in the formation of the spatial structure of a single-core island. In the land use distribution pattern proposed by the genetic algorithm at the regional level, the highest concentration of land uses was observed in Areas A2 and A3 (specifically A32, A21, A23, and A24), while Area B (notably B11) exhibited the lowest share. This suggested a shortage of population attraction centers per capita in Areas A1 and A2, alongside a more favorable per capita distribution of these centers in Area B under the current conditions. In the proposed land-use distribution model utilizing the genetic algorithm at the district level, the highest concentration of land uses was found in Zones A2 and A3, while Zone C (C1) had the lowest share. This indicated that enhancing the role of regional population-attracting centers in A2 and A3 could promote a more balanced spatial distribution of the population. Overall, the findings illustrated an inverse relationship between the spatial distribution of barren lands and the presence of service-functional centers and activity hubs: areas with fewer such centers tended to have a higher proportion of barren land. Furthermore, the underutilization of land and diminished spatial dynamism in specific urban zones (particularly Zones B and C) significantly contributed to spatial imbalances in population distribution. However, the untapped potential of barren and brownfield lands presented a valuable opportunity to allocate space for service-oriented and activity-based land uses. The uneven distribution of service-functional centers and activity hubs coupled with unchecked horizontal expansion further intensified spatial imbalance. Consequently, implementing restrictions on uncontrolled urban sprawl—especially in the southern, southeastern, and western peripheries of Yazd—and advocating for an endogenous development approach were crucial steps toward addressing spatial disproportionality. The results of this study underscored the necessity of adopting a comprehensive strategy for urban land management and spatial planning to effectively utilize existing resources and establish a balanced spatial structure for Yazd. This approach may also be applicable to other cities with significant areas of barren and brownfield lands.
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