Sustainability of Isfahan’s Historical and Tourism Attractions Under the Threat of Land Subsidence: An Analysis of Geospatial Driving Factors

Introduction
Tourism is considered one of the most significant economic resources in many regions, and attention to its various associated dimensions is essential. In this regard, the study of land subsidence and the geographical factors influencing it particularly in terms of its impact on historical monuments and tourist attractions requires a comprehensive approach. The urgency of this research is further underscored by recent reports of damage to numerous historical structures across different regions of the country caused by subsidence. In some cases, the appearance of wall cracks, subsiding foundations, and tilting buildings without any apparent external cause suggests the presence of a phenomenon unfolding within the deeper layers of the earth. If these changes are left unaddressed by scientific and managerial action, a significant portion of the nation's cultural heritage could be lost in the not-so-distant future. In this context, the present study aims to analyze the geographical factors contributing to land subsidence and its effects on the stability of historical and touristic structures, focusing on the city of Isfahan. As one of Iran’s cultural and civilizational hubs, Isfahan hosts hundreds of historical buildings from various periods, particularly the Safavid era. The location of these monuments in plains that are highly vulnerable to subsidence highlights the importance of identifying the underlying causes and the resulting consequences. Although Isfahan has long been a central destination in Iran’s tourism sector and has received considerable attention from planners, it appears that the management of geomorphological hazards such as land subsidence remains underdeveloped. Therefore, this study seeks to scientifically examine the role of geographical factors in the formation of land subsidence and to analyze its impact on the historical and touristic heritage of the city.
 
Methodology
The research method is descriptive-analytical in nature and applied in terms of its objective. It examines the relationship between land subsidence and the influence of geographical factors on its development in historical and touristic structures of Isfahan city. The data used in this study are spatial in nature. Initially, in order to identify the geographical factors, a review of library sources was conducted. Then, in the second stage, the data and information layers for each factor were prepared. The geographical data and factors examined include elevation, slope, precipitation, temperature, traffic, population, distance from metro lines, distance from the river, and groundwater levels. This study is designed in a five-step process, with each step carefully executed for a specific purpose. In the first step, the researcher extracted the variables and factors influencing land subsidence. Then, in the second step, the conditions of Isfahan city and parameters such as rainfall, population, and land use were considered. In the third stage, the required data were collected from relevant websites and official organizations. In the fourth stage, the amount and condition of subsidence in Isfahan city especially in historical and touristic areas were estimated using SNAP software and satellite data from the Alaska website. Finally, in the fifth stage, the relationship between geographical factors and the extent of land subsidence was analyzed using multiple linear regression.
 
Findings
The analysis of multiple linear regression data over the period 2016 to 2024 reveals that land subsidence in the historical and touristic zones of Isfahan has been influenced by various geographical factors, with the nature and intensity of these effects changing over the years. Broadly speaking, three major categories of influencing factors have played a key role in the occurrence and intensification of subsidence: human factors (population and traffic), topographic characteristics (land slope), and the status of groundwater resources. uring this nine-year period, population growth and urban traffic representing physical and anthropogenic pressures on the land have consistently shown a positive and statistically significant correlation with subsidence. This underscores the impact of urban development activities and increasing population density on ground instability, especially in historical areas, where outdated and fragile urban infrastructure is common. The pressure from heavy vehicle movement and vibrations caused by traffic can exacerbate subsidence and damage historical structures.On the other hand, the topographic features of the terrain, particularly slope, have emerged as a critical natural factor that has maintained a significant direct relationship with subsidence in most years. Steeper slopes, due to their geotechnical sensitivity and greater susceptibility to soil displacement, have been more vulnerable to subsidence. This highlights the need for particular attention to the location and preservation of historical structures in geologically sensitive areas.
Moreover, the role of groundwater resources especially the decline in groundwater levels—has repeatedly appeared in the data as a decisive factor in subsidence intensification. Groundwater depletion, which may result from over-extraction, reduced precipitation, or climate change, leads to a reduction in pore water pressure and an increase in soil compaction, thereby accelerating land subsidence—posing a serious risk to historical sites.Other factors, such as proximity to rivers and metro stations, have shown a statistically significant correlation with subsidence in some years, indicating the role of spatial location and urban infrastructure in this phenomenon. Specifically, proximity to metro lines has, in certain cases, been associated with increased subsidence, likely due to the instability caused by excavation and construction activities an issue that has been rarely addressed in previous studies and thus represents an innovative aspect of this research.In contrast, factors such as elevation, precipitation, and temperature have generally not shown a consistent or significant correlation with subsidence over the years. This may be due to their indirect influence, the variability of climatic conditions, or the scale of analysis used.The main limitations of this study include the temporal constraint of data availability, which covers only the 2016–2024 period; the exclusion of detailed local geological factors and structural specifics; and the lack of high-resolution data on groundwater and precipitation at a micro scale. Furthermore, the long-term effects of climate change were not comprehensively examined. Hence, the results should be interpreted with caution and future studies are recommended to utilize broader datasets and more integrated modeling approaches.
 
Discussion and Conclusion
Overall, the findings indicate that land subsidence in the historical and touristic areas of Isfahan is a complex, multi-factorial phenomenon influenced by human pressures, natural conditions, and water resource management. This insight, especially when compared to previous studies that primarily focused on isolated factors such as groundwater extraction or geological characteristics, presents a significant innovation by offering a multidimensional and integrated perspective on the issue. Accordingly, to ensure the effective preservation of this valuable heritage, it is essential to develop comprehensive and integrated management plans. These should include continuous geological monitoring, regulation of human activities—particularly in areas of heavy traffic and population density optimal management of groundwater resources, and special attention to the topographical features of sensitive zones.