Bahram Bakhtiyari; Arash Malekian; Ali Akbar Nazari Samani; Reza Shahbazi
Abstract
Land subsidence is a complex geomorphological phenomenon characterized by the vertical downward movement of the Earth's surface, with far-reaching implications for ecosystems, human infrastructure, and the environment. This study aims to analyze the relationship between groundwater level decline and ...
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Land subsidence is a complex geomorphological phenomenon characterized by the vertical downward movement of the Earth's surface, with far-reaching implications for ecosystems, human infrastructure, and the environment. This study aims to analyze the relationship between groundwater level decline and land subsidence in the Tehran-Shahryar plain, using measured data. The research methodology is based on advanced remote sensing techniques, including Interferometric Synthetic Aperture Radar (InSAR) using Sentinel-1 satellite images, and analysis of groundwater level data using statistical methods. A key innovation of this research is the simultaneous use of all available piezometers in the study area and the calibration of radar data with accurate ground leveling measurements. The findings of the study indicate that groundwater level decline is the main trigger of subsidence in the region. Cross-correlation analysis of the data reveals a time lag of 0 to 3 years, with an average of 1 year, between groundwater level decline and the occurrence of subsidence across the entire area. This time lag is due to complex geotechnical processes in the water-bearing sedimentary layers, especially in areas with complex geological structures. Spatial-temporal analyses show that the Tehran-Shahryar plain is facing a high potential for subsidence, with average subsidence rates exceeding 23 mm per year in some areas. This trend can pose serious threats to critical infrastructure, engineering structures, and the region's ecosystem. The implications of this study highlight the importance of integrated groundwater management, controlled extraction, and continuous monitoring of geodynamic changes. Moreover, the results can provide a suitable scientific basis for making major decisions in water resources management and mitigating environmental hazards.
Peyman Amin; Mohammad raza ekhtesasi
Abstract
In the last two decades, the land subsidence, especially in fine-grain plains, cracks emerged in YazdArdakan plain, it is called soil crack. One of the important assumptions in relation to emergence of this phenomenon, withdrawal of water from underground aquifers and decrease the hydro dynamic pressure ...
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In the last two decades, the land subsidence, especially in fine-grain plains, cracks emerged in YazdArdakan plain, it is called soil crack. One of the important assumptions in relation to emergence of this phenomenon, withdrawal of water from underground aquifers and decrease the hydro dynamic pressure and dense sediment. This phenomenon happens in fine-grained sediment and caused damage to building structures, roads, masts. the case study is clay plain lands without desert pavement in East of Yazd. For sampling, 12 samples were taken from three points were selected which one of them in the vicinity of crack and two other points were within 100 meters of side of crack in each point, four profiles were drilled from zero to 120 cm depth. On samples some experiments such as the indicators of changing bulk modulus were measured in different moistures in galvanized metal cube boxes with dimensions of 20 cm, some experiments were done such as Atterberg limit tests, divergence and failure limit. The results showed that liquid limit of the crack’s territory is near to 29 percent and moisture limit of crack is close to 4 percent. the most vertical and horizontal shrinkage in crack soils were 11 and 6 percent respectively. In other words, in per meter depth of sediment, 11 cm subsidence in areas with moisture less than 4 percent is not unexpected. With regard to the specific circumstances of the area, is proposed structural projects, gas lines, water pipes and bridges is not done in these areas.
