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Volume 40, Issue 3 (2025)
GeoRes 2025, 40(3): 221-230 |
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Received: 2025/07/29 | Accepted: 2025/09/2 | Published: 2025/09/7
Received: 2025/07/29 | Accepted: 2025/09/2 | Published: 2025/09/7
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Soltani-Samet M, Soltani H, Galoie M. Land Subsidence Due to Groundwater Depletion in Qazvin Plain-Buein Zahra Using Interferometric Synthetic Aperture Radar Method. GeoRes 2025; 40 (3) :221-230
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1- Department of Civil Engineering, Buein Zahra Technical University, Buein Zahra, Iran
2- Department of Civil Engineering, Faculty of Technical and Engineering, Imam Khomeini International University, Qazvin, Iran
2- Department of Civil Engineering, Faculty of Technical and Engineering, Imam Khomeini International University, Qazvin, Iran
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Background
The global water scarcity crisis and the overexploitation of groundwater resources in arid regions, particularly in Iran, have led to the widespread occurrence of land subsidence. The Buein Zahra plain in Qazvin Province represents one of the critical areas, experiencing severe subsidence along with extensive environmental and infrastructural consequences.
Previous Studies
Previous studies have extensively examined the relationship between excessive groundwater extraction and the occurrence of land subsidence. Galloway and Burbey (2011) have identified subsidence as a direct result of reduced pressure in alluvial aquifers due to overextraction. Faso et al. (2020), in a United Nations report, highlight unsustainable groundwater withdrawal and climate change as key accelerators of global subsidence. In Iran, multiple studies, including Motagh et al. (2008) and Hosseini-Moghari et al. (2020), emphasize the role of declining water tables and improper aquifer exploitation in increasing subsidence rates across the country’s plains. Shadfar et al. (2016) have reported the impact of unsustainable extraction on sinkhole formation, while Pourghasemi et al. (2018), through subsidence hazard zoning in Buin Zahra, have identified a substantial portion of the city at high risk. Additionally, Galoie and Motamedi (2022) have investigated runoff management strategies aimed at restoring groundwater levels in this province.
Aim(s)
The aim of the present study was to investigate the impact of excessive groundwater extraction on the rate of land subsidence.
Research Type
The present study was applied research.
Research Society, Place and Time
This study was an applied research conducted in 2025. The research population comprised satellite data related to the Qazvin Plain, particularly the Buin Zahra area in the southern part of Qazvin Province. The study area is classified climatically as a relatively hot and dry region with an average annual rainfall of about 220 mm. The data used included 16 Sentinel-1 satellite images from 2019 to 2022.
Sampling Method and Number
In this study, purposeful sampling was employed to select satellite data with high quality and adequate spatial coverage. The samples consisted of 16 Sentinel-1 satellite images with VV polarization of the GUNW (Geocoded Unwrapped Interferogram) type. These images, spanning 2019 to 2022, were chosen to accurately capture the spatial and temporal variations of land subsidence. The data were obtained from the Alaska Satellite Facility and NASA’s ARIA project.
Used Devices & Materials
In this study, remote sensing data and tools were used to analyze land subsidence. The primary materials and equipment included Sentinel-1 satellite images with VV polarization of the GUNW type (Geocoded Unwrapped products). These data were obtained from the Alaska Satellite Facility (ASF) and NASA’s ARIA project. For data processing and analysis, JPL ISCE2 software (version 2.3.2) was used to extract SAR data, and ESA SNAP was employed for geometric correction and calculation of vertical ground displacements. Additionally, geotechnical logs and quantitative groundwater level data were utilized to validate the results. Interferometric Synthetic Aperture Radar (InSAR) was applied as the main analytical method to determine the rate and spatial extent of subsidence in the study area.
Findings
The SNAP software outputs (version 11.0.0) were imported into ArcGIS (version 10.8.2) to produce maps of land subsidence rates and spatial distribution (Figure 1). Results indicated that the highest subsidence occurred in the northern and western parts of the Buein-Zahra region, with a cumulative maximum deformation of 695 mm between 2019 and 2022 and an average annual rate of approximately 200 mm. The deformation range varied between +616 mm and −695 mm, indicating both uplift and sinking movements.
Figure 1) Cumulative land subsidence values calculated in the Bouin-Zahra region, expressed in millimeters (2019–2022).
To examine the relationship between subsidence and groundwater level decline, data from 156 wells during 2019–2024 were analyzed (Figure 2). Interpolation results (Figures 3 and 4) showed that the western part experienced the greatest water table drop, with an average decline of 6 m in the central area and 10.65 m in the west, representing a 77.5% higher decrease in the western region.
Figure 2) Location of existing wells in the study area and their spatial distribution
Figure 3) Interpolated groundwater table levels during 2019–2024
Figure 4) Groundwater table levels in the study area during 2019–2024
Fault mapping (Figure 5) revealed high fault density in the southern and southwestern parts of the plain, which may exacerbate subsidence due to reduced mechanical resistance and increased hydraulic conductivity. Land-use analysis (Figure 6) indicated that northern areas are primarily agricultural and experienced the highest subsidence, whereas southern residential areas, located near faults, face elevated risk of ground movement damage.
Figure 5) Map of existing faults within the study area
The global water scarcity crisis and the overexploitation of groundwater resources in arid regions, particularly in Iran, have led to the widespread occurrence of land subsidence. The Buein Zahra plain in Qazvin Province represents one of the critical areas, experiencing severe subsidence along with extensive environmental and infrastructural consequences.
Previous Studies
Previous studies have extensively examined the relationship between excessive groundwater extraction and the occurrence of land subsidence. Galloway and Burbey (2011) have identified subsidence as a direct result of reduced pressure in alluvial aquifers due to overextraction. Faso et al. (2020), in a United Nations report, highlight unsustainable groundwater withdrawal and climate change as key accelerators of global subsidence. In Iran, multiple studies, including Motagh et al. (2008) and Hosseini-Moghari et al. (2020), emphasize the role of declining water tables and improper aquifer exploitation in increasing subsidence rates across the country’s plains. Shadfar et al. (2016) have reported the impact of unsustainable extraction on sinkhole formation, while Pourghasemi et al. (2018), through subsidence hazard zoning in Buin Zahra, have identified a substantial portion of the city at high risk. Additionally, Galoie and Motamedi (2022) have investigated runoff management strategies aimed at restoring groundwater levels in this province.
Aim(s)
The aim of the present study was to investigate the impact of excessive groundwater extraction on the rate of land subsidence.
Research Type
The present study was applied research.
Research Society, Place and Time
This study was an applied research conducted in 2025. The research population comprised satellite data related to the Qazvin Plain, particularly the Buin Zahra area in the southern part of Qazvin Province. The study area is classified climatically as a relatively hot and dry region with an average annual rainfall of about 220 mm. The data used included 16 Sentinel-1 satellite images from 2019 to 2022.
Sampling Method and Number
In this study, purposeful sampling was employed to select satellite data with high quality and adequate spatial coverage. The samples consisted of 16 Sentinel-1 satellite images with VV polarization of the GUNW (Geocoded Unwrapped Interferogram) type. These images, spanning 2019 to 2022, were chosen to accurately capture the spatial and temporal variations of land subsidence. The data were obtained from the Alaska Satellite Facility and NASA’s ARIA project.
Used Devices & Materials
In this study, remote sensing data and tools were used to analyze land subsidence. The primary materials and equipment included Sentinel-1 satellite images with VV polarization of the GUNW type (Geocoded Unwrapped products). These data were obtained from the Alaska Satellite Facility (ASF) and NASA’s ARIA project. For data processing and analysis, JPL ISCE2 software (version 2.3.2) was used to extract SAR data, and ESA SNAP was employed for geometric correction and calculation of vertical ground displacements. Additionally, geotechnical logs and quantitative groundwater level data were utilized to validate the results. Interferometric Synthetic Aperture Radar (InSAR) was applied as the main analytical method to determine the rate and spatial extent of subsidence in the study area.
Findings
The SNAP software outputs (version 11.0.0) were imported into ArcGIS (version 10.8.2) to produce maps of land subsidence rates and spatial distribution (Figure 1). Results indicated that the highest subsidence occurred in the northern and western parts of the Buein-Zahra region, with a cumulative maximum deformation of 695 mm between 2019 and 2022 and an average annual rate of approximately 200 mm. The deformation range varied between +616 mm and −695 mm, indicating both uplift and sinking movements.
Figure 1) Cumulative land subsidence values calculated in the Bouin-Zahra region, expressed in millimeters (2019–2022).
To examine the relationship between subsidence and groundwater level decline, data from 156 wells during 2019–2024 were analyzed (Figure 2). Interpolation results (Figures 3 and 4) showed that the western part experienced the greatest water table drop, with an average decline of 6 m in the central area and 10.65 m in the west, representing a 77.5% higher decrease in the western region.
Figure 2) Location of existing wells in the study area and their spatial distribution
Figure 3) Interpolated groundwater table levels during 2019–2024
Figure 4) Groundwater table levels in the study area during 2019–2024
Fault mapping (Figure 5) revealed high fault density in the southern and southwestern parts of the plain, which may exacerbate subsidence due to reduced mechanical resistance and increased hydraulic conductivity. Land-use analysis (Figure 6) indicated that northern areas are primarily agricultural and experienced the highest subsidence, whereas southern residential areas, located near faults, face elevated risk of ground movement damage.
Figure 5) Map of existing faults within the study area
Figure 6) Land use map of the study plain (green in the north: agricultural; red in the south: urban)
Main Comparisons to Similar Studies
The findings of this study are largely consistent with previous research and confirm the increasing trend of land subsidence in the Qazvin Plain. Specifically, Babaee et al. (2020) have reported an average subsidence rate of 40–65 mm per year, whereas the present study indicated a rate of approximately 200 mm per year in recent years, reflecting a significant intensification of the phenomenon. Nouri Qeydari (2014) also reports a maximum subsidence of around 83.4 mm per year, emphasizing the role of fine-grained soils and groundwater table decline. More recent studies, including Janbaz Fotamy et al. (2023) with a rate of 470 mm per year and Farshbaf et al. (2024) with 132 mm per year, further confirm the acceleration of subsidence. Likewise, Moghaddam & Kholghi (2025) have documented a groundwater level decline of over 18 meters over the past two decades. Collectively, these comparisons strongly indicate a close correlation between excessive groundwater extraction and the accelerated rate of subsidence in the Qazvin region.
Suggestions
Effective monitoring and control of groundwater extraction, particularly in subsidence-prone areas, is essential to prevent unauthorized or excessive withdrawals from wells. Additionally, careful and continuous planning to restrict construction in areas with high subsidence rates and to optimize the use of groundwater resources constitutes a key measure to prevent damage to infrastructure and avert crises resulting from this phenomenon.
Conclusion
Groundwater levels in the western parts of the Buein-Zahra region have declined more than in the central areas. Additionally, the highest land subsidence occurs in the northern and western sections, which is directly associated with the decrease in groundwater levels in these areas.
Acknowledgments: To analyze groundwater fluctuations, long-term well data from the Bouin Zahra region were utilized. The authors wish to express their sincere gratitude to the research team, especially the esteemed Dr. Artemis Mo’tamedi, for her continuous support which played a pivotal role in completing this study, and to the Qazvin Regional Water Authority for providing the necessary data and information.
Ethical Permission: This article has not been published in any domestic or international journals.
Conflict of Interest: The authors declare no conflicts of interest with any organizations or individuals. The purpose of this paper is solely to present practical methods in the field of Geographic Information Systems (GIS) and their effective application in environmental hazard analysis.
Author Contributions: Soltani Samet MM (first author), Methodologist/Principal Researcher (35%); Soltani H (second author), Introduction Writer/Assistant Researcher/Statistical Analyst (35%); Galoie M (third author), Methodologist / Discussion Writer (30%)
Funding: This study was conducted based on the research activities of two undergraduate students at the Buein Zahra Technical and Engineering Center and their personal interest. No formal financial support was provided by any official organizations or executive bodies.
Keywords:
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