نوع مقاله : مقاله پژوهشی
نویسندگان
1 کارشناسی ارشد مهندسی عمران، گرایش مهندسی و مدیریت منابع آب، دانشگاه حکیم سبزواری
2 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه حکیم سبزواری
3 مرکز پژوهشی علوم جغرافیایی و مطالعات اجتماعی، دانشگاه حکیم سبزواری
4 گروه جغرافیای طبیعی، دانشکده علوم جغرافیایی و برنامه‌ریزی، دانشگاه اصفهان
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
1. Introduction
Land subsidence is a significant and often devastating geological phenomenon that can lead to severe consequences for both human societies and infrastructural stability. It refers to the gradual sinking or settling of the Earth's surface, which, if left unchecked, can cause irreparable financial losses, damage to critical infrastructure, and threats to human safety. The driving forces behind land subsidence are typically related to human activities, especially the excessive extraction of natural resources. Among these, the over-withdrawal from groundwater aquifers is one of the most prevalent and damaging causes. This phenomenon occurs worldwide, with water-scarce countries like Iran increasingly facing land subsidence issues. In Iran, the problem has become particularly pronounced in the eastern and central regions, where groundwater resources are heavily exploited to meet the demands of agriculture, industry, and urbanization. One such affected area is the Esfarayen plain, which suffers from rapid land subsidence rates. The Esfarayen plain, being one of these vulnerable zones, has drawn particular attention from researchers and policymakers due to its high rate of land sinking. This research aims to provide a detailed assessment of land subsidence in the Esfarayen aquifer, using advanced remote sensing technology—specifically radar interferometry—to evaluate its extent.
2. Research Methodology
The methodology employed in this study combines remote sensing techniques with hydrogeological data analysis. The primary data source consists of 55 Sentinel-1A satellite Synthetic Aperture Radar (SAR) images, captured over seven years from 2015 to 2022. These images serve as the foundation for the land deformation analysis, providing high-resolution data capable of detecting even minor changes in ground elevation. The processing of these images was carried out using specialized software tools, primarily the Sentinel Application Platform (SNAP) and ArcGIS. The raw SAR data underwent a series of pre-processing steps, including calibration, and filtering, to prepare them for interferometric analysis. The key technique used is radar interferometry, also known as InSAR (Interferometric Synthetic Aperture Radar). This method involves comparing complex phase differences between pairs of SAR images to detect surface displacement with centimeter or even millimeter accuracy. The application of InSAR allowed us to estimate the amount and spatial distribution of land subsidence over the study period, resulting in a detailed and comprehensive map of subsidence zoning within the Esfarayen aquifer. To examine the relationship between groundwater abstraction and land subsidence, the study also incorporated hydrogeological data. Changes in water table levels were monitored using records from existing piezometric wells and data on groundwater extraction. A groundwater level contour map was constructed using ArcGIS, facilitating the visualization of water level declines and their correlation with observed land subsidence patterns.
Results and discussion
The analysis of InSAR data revealed that land subsidence in the Esfarayen aquifer varies significantly acrossThe analysis of InSAR data indicated that the central and northern parts of the aquifer are most affected, with the maximum subsidence rate reaching 12.6 centimeters annually within an 80-square-kilometer zone characterized by dense well exploitation and extensive agricultural activities located in the central part. The overall average subsidence rate in the area was found to be around 28 millimeters per year over the study period. These measurements suggest that the subsidence in these zones is continuous and relatively rapid, primarily driven by ongoing groundwater extraction. Furthermore, the hydrogeological data underscored a concerning trend: the water table in the aquifer has been steadily declining, with an average annual decrease of about 36 centimeters over the seven years. This decline is a clear indicator of overexploitation of groundwater resources, placing additional stress on the aquifer's stability. A crucial finding from the correlation analysis suggests that for every meter reduction in the groundwater level, the land surface subsides by around 8 centimeters. This relationship emphasizes the direct impact of groundwater withdrawal on land stability and underscores the importance of sustainable water management. The spatial analysis also highlighted that areas with the highest density of groundwater extraction wells coincide with regions experiencing the most significant land subsidence. The distribution of these wells, often concentrated in agricultural zones, exacerbates the problem by extracting large volumes of water, reducing pore pressure within the soil, and causing it to compact. This compaction leads to permanent ground settlement, which in turn can damage infrastructure such as roads, pipelines, and buildings, and increase the risk of flooding and other land-related hazards. The findings of this research align with global observations that excessive groundwater pumping leads to land subsidence, a process that can become irreversible if not addressed promptly.
3. Conclusion
The comprehensive analysis conducted in this study confirms a strong link between groundwater abstraction and land subsidence in the Esfarayen plain. The combination of remote sensing data and hydrogeological investigations revealed that the most significant land sinking occurs in zones with high well density and steep groundwater level declines. The results show that land subsidence is an ongoing process with potentially severe consequences for infrastructure, agriculture, and most importantly, the sustainability of groundwater resources. Given the multifaceted nature of land subsidence, which is influenced by various natural and anthropogenic factors, it is recommended that future research expands to include other potential causes such as mining activities and land-use changes. Moreover, establishing a sustainable groundwater management framework and implementing measures to reduce excessive withdrawals are urgent tasks to mitigate future land subsidence. Proactive monitoring and enforcement of water use regulations, combined with efforts to improve water use efficiency, could significantly slow or halt further subsidence and help secure the long-term vitality of the Esfarayen aquifer.
کلیدواژه‌ها [English]
References
Zandi R, Nasiri A, Shafiei N, & Farzin Kia R. (2019). The application of remote sensing in environmental sciences (principles and techniques). Greenery Hakim Sabzevari University.(In persian).
Zanganeasadi, M.A., Zandi, R., & Shafiei, N. (2023). Measurement and evaluation of rice and summer crops on the amount of land subsidence (case study: Noorabad Reservoir, Fars Province, Iran). Quantitative Geomorphological Research. 12(2): 184-199. (In Persian). 10.22034/gmpj.2023.393690.1432
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