Journal of Engineering Geology

Determining Land Subsidence Rate and Its Relationship with Groundwater Level Decline Using Satellite Data in the Damghan Aquifer

Houshang Khairy

Land subsidence is a major geomorphological hazard in arid and semi-arid regions, primarily driven by excessive groundwater extraction. In such areas, declining water tables can cause irreversible compaction of fine-grained sediments, reduced aquifer storage capacity, and damage to critical infrastructure. This study aims to monitor subsidence rates in the Damghan aquifer and analyze their relationship with groundwater level decline using satellite imagery and ground-based data. The study area covers approximately 1,522 km² of the Damghan aquifer in Semnan Province, characterized by a layered and heterogeneous alluvial structure. Data sources include Sentinel-1A radar images (2017–2021), groundwater level records from 38 observation wells (2012–2019), and drilling logs from 13 production wells. Radar data were processed using SNAP software, and spatial-temporal analyses were conducted in ArcGIS and GMS environments. Results indicate that groundwater levels in central and southeastern parts of the aquifer have declined by over 7 meters, with an average annual drop of 0.46 meters. Radar interferometry maps revealed subsidence rates of up to 32 cm in these zones. Soil texture and saturated layer thickness analyses showed that areas with high clay and silt content are more sensitive to water level decline and subsidence. Zoning results indicate that 44% of the aquifer surface is affected, with the highest rates observed in zones with alluvial thickness exceeding 230 meters. Field evidence—including surface fissures, well damage, sinkholes, and structural failures—highlights the practical implications of this phenomenon. Findings underscore the urgent need for continuous groundwater monitoring and targeted management to mitigate infrastructure risks and ensure environmental sustainability.

A Field-Based Investigation of Land Subsidence Indicators in Alborz Province, Iran

Ali Ghanbari

Land subsidence represents a multifaceted geotechnical hazard that exerts profound impacts on environmental stability, infrastructure resilience, and socio-economic security. This research presents a systematic field-based assessment of subsidence manifestations across the Hashtgerd, Eshtehard, and Karaj plains in Alborz Province, derived from extensive surveys conducted during the spring and summer of 2025. Diagnostic indicators—including extensional and compressional ground fissures, localized structural deformations, wellhead displacements, large-scale surface cracks, and variations in groundwater levels—were systematically documented. The Hashtgerd plain, particularly the Saeidabad, Sepehr, and Najmabad areas, exhibited the highest density of subsidence evidence, encompassing progressive surface settlements, widespread fissuring, and instability of near-surface strata. In the Eshtehard plain, structural cracking in school buildings, ground ruptures adjacent to transmission towers, and failures in retaining walls were frequently observed. Deep surface fissures were also identified in the Fathabad region, situated between Eshtehard and Buin Zahra. Conversely, despite significant groundwater withdrawal, field surveys in parts of the Karaj plain revealed no pronounced subsidence indicators. The findings highlight a strong spatial correlation between the severity of subsidence and geological heterogeneity, unregulated groundwater exploitation, and the absence of smart metering systems in wells. This study underscores the urgent need for integrated monitoring frameworks, adaptive management strategies, and the application of advanced remote sensing technologies to mitigate and control the expansion of land subsidence in Alborz Province.

A Comprehensive Study on the Effects of Geometric and Geomechanical Parameters on Crown Pillar Behavior during the Transition from Open-Pit to Underground Mining

Saeed Mahdavi

Due to the deepening of open-pit mines and the associated environmental considerations, the current era has been called the "return to underground mining period." One of the fundamental considerations in the transition from open-pit to underground mining is the design of crown pillars based on economic and technical considerations. As result of uncertainties in this research topic, the present study employs three-dimensional numerical simulation to investigate the interactive effects of geometric and geomechanical parameters on crown pillar behavior during the transition to underground mining. The pillar behavior was evaluated based on displacement magnitude and plastic zone volume of the pillar. The results of the numerical simulation showed that geometric parameters play a much more significant role than rock mechanical properties. Among geometric parameters, the pillar dimension index (product of pillar thickness and span) and crown pillar span have a decisive role in controlling pillar behavior. From a geomechanical perspective, within the range of variations considered in this research, rock elastic modulus was identified as the influential parameter on crown pillar behavior, which controls crown pillar behavior with a critical value of 7 GPa. The crown pillar span, as the second most influential parameter, can predict crown pillar displacement with a correlation coefficient of 0.83, and the pillar dimension index can estimate the plastic zone volume in the pillar with 20% accuracy.

Comparative Analysis of Probabilistic Slope Stability Analysis Using PLAXIS LE V21, GeoStudio 2024, and Slide2

seyed ali asghari pari

The present study systematically compares probabilistic slope stability analysis using three widely used geotechnical engineering software packages: PLAXIS LE V21, GeoStudio 2024 (SLOPE/W module), and Slide2. Given the critical importance of risk assessment and the inherent uncertainty in soil parameters, probabilistic analysis has emerged as an essential approach for quantifying uncertainties and calculating key metrics such as probability of failure and reliability index. This research evaluates the capabilities, accuracy, efficiency, and limitations of each software by performing identical analyses on three distinct scenarios (homogeneous soil, three-layered soil, and pseudo-static conditions) while employing ten common limit equilibrium methods. The results demonstrate that all three software packages are capable of conducting probabilistic analyses with acceptable accuracy; however, each offers distinct strengths: Slide2 is ideal for complex risk analyses due to its specialized tools and advanced graphical visualizations; GeoStudio is better suited for routine projects owing to its intuitive user interface and seamless integration with other modules; and PLAXIS LE excels in computationally demanding problems through its high numerical accuracy and hybrid finite element limit equilibrium (FELA) approach. This study provides practical guidance for engineers in selecting the most appropriate software based on project complexity, required accuracy, and available resources. It also emphasizes the advantages of probabilistic approaches over traditional deterministic analyses in effective risk management.