Quantitative analysis of the physical development pattern in Yazd city

The dynamic and rapid growth of urbanization and, as a result, the physical changes in cities have led to many challenges and problems. Physical development is manifested in varied forms, ranging from scattered to dense and intelligent. Each form of development has its advantages and disadvantages. Accordingly, without proper planning and consideration of the existing context, unmanaged city growth can cause direct and indirect harm to the urban environment, with citizens and resources being the primary victims and potential future heritage. Iranian cities have also contributed to this global experience based on many variables, such as demographic, social, and economic movements. In the meantime, the historical city of Yazd, as a precious legacy of its predecessors, has experienced a coherent and sustainable form of development by relying on creativity and initiative. The physical structure has been transformed into different types in the last few decades. Continuing this situation not only disrupts the city’s physical cohesion but also exacerbates the economic, social, and legal issues. Therefore, the present research seeks to answer whether the findings of different models in the analysis of the physical development pattern in Yazd City yield a unified result or deviate from one another.

The current research is an applied research in terms of purpose and adopts a descriptive-analytical approach. The data and information required for analysis in the research have been collected through bibliographic and field studies. Aligned with the research objectives, the study employs quantitative analytical models, namely Shannon entropy, Heldren, Moran’s coefficient, and a comparison of filled and empty urban land. Additionally, multi-time satellite images have been incorporated to analyze the data and investigate the physical development pattern of the city.

In this research, various quantitative analytical models such as Shannon’s entropy (2006-2021), Heldren’s (1996-2016), Moran’s coefficient (2006-2016), comparison of full and empty urban land (1398) and multi-temporal satellite images in the period 1990-2000-2013 and 2021 have been used to study the physical development pattern of the city. The results of the study of the city’s physical development using multi-temporal satellite images in 1990-2000-2013-2021 indicate a 71.46% growth of the city during these 31 years. Contrasting Shannon’s entropy model between 1385 and 1400 reveals the city’s dispersed growth over the 15-year period. In accordance with Heldron’s model, using 1345 as the starting point and 2016 as the endpoint, it is observed that 59% of the overall physical development or city size increase is attributed to population growth, while the remaining 41% is linked to the scattered development of the city. The findings from the comparison of Moran’s coefficient in 2006 and 2016 indicate a shift in the spatial distribution pattern of Yazd city’s population density, transitioning from a random pattern to a scattered one. Additionally, when evaluating the ratio of dense tissue area to the total city size in Yazd (coefficient 0.015), the comparison reveals that the growth rate of the city area corresponds proportionally to the growth rate of the population during the specified period.

The results of all these methods indicate that the city of Yazd experiences scattered and unbalanced physical development. According to the results of the study, Yazd City is located in an area where the town’s per capita services and facilities are high, with a large volume of services that can serve twice its population. Examining the results, it becomes evident that in Yazd City, the speed of inactive urban levels increases in favor of the active groups as one moves from the central area to the surrounding regions. These functional levels not only exhibit significant potential for internal development but also present a viable option to prevent the sprawling expansion of the city.