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 one of the major geomorphological hazards in arid and semi-arid regions. It is primarily caused by excessive groundwater extraction. In such areas, a decline in groundwater levels can lead to the irreversible compaction of fine-grained layers, a reduction in storage capacity, and damage to critical infrastructure. This study aims to monitor the rate of land subsidence in the Damghan aquifer and analyse its relationship with groundwater decline, using satellite data, piezometric information and field evidence. The study area covers part of the Damghan aquifer in Semnan Province, spanning approximately 1,522 km². It contains an unconfined aquifer within heterogeneous alluvial deposits. The dataset includes Sentinel-1A images from 2017 to 2021, records from 38 observation wells from 2017 to 2022, and drilling logs from 13 exploitation boreholes. The results indicated that the decline in groundwater levels in the central and south-eastern parts of the aquifer reached 5 metres, with an average annual rate of approximately 0.33 metres. Radar interferometry maps confirmed an average Analysis of soil texture and saturated thickness revealed that zones with higher percentages of clay and silt are more sensitive to groundwater decline. Even small drawdowns in boreholes containing fine-grained sediments resulted in noticeable subsidence, whereas boreholes containing coarse-grained sediments showed limited deformation. Field evidence, including casing protrusion in piezometer wells of up to 27 cm, the formation of initial sinkholes and changes in natural drainage patterns, highlights the practical implications of this phenomenon. The findings of this study demonstrate that, in interaction with geological characteristics and soil texture, groundwater decline is the main driver of subsidence in the Damghan aquifer. Therefore, continuous groundwater monitoring and targeted management of exploitation are essential to mitigate risks and ensure the region's environmental and economic sustainability.

Comparative analysis of probabilistic analysis of slope stability using software Plaxis LE V21, GeoStudio 2024 and Slide2

seyed ali asghari pari

This study systematically compares probabilistic slope stability analyses performed using three widely used geotechnical engineering software packages: PLAXIS LE V21, GeoStudio 2024 (SLOPE/W module) and Slide2. Probabilistic analysis has emerged as an essential approach for quantifying uncertainties and calculating key metrics such as probability of failure and reliability index, given the critical importance of risk assessment and the inherent uncertainty in soil parameters. This research evaluates the capabilities, accuracy and efficiency of each software package, as well as their respective limitations, 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 show that, as the complexity of the problem increases, the factor of safety decreases while the probability of failure and discrepancies between the software packages increase. In the homogeneous scenario, the mean factor of safety ranges from 1.35 to 1.55, depending on the method selected, with a failure probability of 8–12%, and inter-software differences of less than 5%. In the layered scenario, the mean factor of safety decreases to 1.30–1.40, with inter-software discrepancies reaching approximately 15%. Under pseudo-static conditions, the mean factor of safety reduces by around 21% (to 1.15), the probability of failure rises to an average of 27%, and the inter-software discrepancies reach 25%. Advanced methods (Morgenstern-Price and Spencer) yield higher safety factors than simple methods (Ordinary/Fellenius). In terms of software performance, Plaxis LE offers the greatest accuracy in complex conditions, GeoStudio provides the most conservative estimates and, thanks to its advanced graphical tools, Slide2 is a suitable option for probabilistic risk assessment.

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 associated environmental concerns, the current period has been termed the 'return to underground mining era'. One of the key factors in transitioning from open-pit to underground mining is designing crown pillars based on economic and technical considerations. Due to the uncertainties surrounding this research topic, the present study uses three-dimensional numerical simulations to investigate the interactive effects of geometric and geomechanical parameters on the behaviour of crown pillars during the transition to underground mining. Pillar behaviour was evaluated based on displacement magnitude and the volume of the plastic zone of the pillar. The results of the numerical simulation showed that geometric parameters play a much more significant role than rock mechanical properties. Of the geometric parameters, the pillar dimension index (the product of the pillar's thickness and span) and the crown pillar's span play a decisive role in controlling pillar behaviour. From a geomechanical perspective, within the range of variations considered in this research, the rock elastic modulus was identified as the parameter most influential on crown pillar behaviour. This parameter controls crown pillar behaviour at a critical value of 7 GPa. Crown pillar span was identified as the second most influential parameter and can predict crown pillar displacement with a correlation coefficient of 0.83. The pillar dimension index can estimate the plastic zone volume in the pillar with 20% accuracy.

A field-based investigation of land subsidence indicators in Alborz province

Ali Ghanbari

Land subsidence is a complex geotechnical hazard with 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, based on extensive surveys conducted in 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, including progressive surface settlement, widespread fissuring, and instability of near-surface strata. In the Eshtehard plain, structural cracking in school buildings, ground ruptures adjacent to transmission towers, and retaining wall failures were frequently observed. Deep surface fissures were also identified in the Fathabad region, which is located between Eshtehard and Buin Zahra. In contrast, 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 and unregulated groundwater exploitation.The absence of smart metering systems in wells also contributed to this issue. 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.

Assessment of the Mashhad-Chenaran aquifer quantitve sutainability in Mashhad city area

Hossein Mohammadzadeh

The intensive exploitation of groundwater resources in arid and semi-arid regions poses serious challenges to the quantitative sustainability of aquifers. The Mashhad–Chenaran aquifer, one of the most important alluvial aquifers in north-eastern Iran and the main source of drinking water for the city of Mashhad, has experienced increasing stress in recent years. This study evaluated the quantitative sustainability of the aquifer during the 2015–2016 to 2021–2022 hydrological periods, based on an integrated analysis of well discharge, aquifer saturated thickness, specific yield (Sy), specific capacity (Q/s) and specific drawdown (S/Q). The results indicate a notable decline in well discharge, particularly in the southeastern and central parts of the aquifer. Concurrently, the saturated thickness of the aquifer decreased. Specific yield declined from approximately 0.95 to 0.25, corresponding to a reduction of around 74% in aquifer storage capacity. Additionally, the specific capacity decreased from approximately 0.63 to 0.43 MCM·yr⁻¹·m⁻¹, representing a reduction of around 32%. Meanwhile, specific drawdown increased from approximately 1.56 to 2.30 m, indicating a 47% increase in water-level decline per unit discharge, as well as a reduction in the hydraulic efficiency of groundwater exploitation. Areas of the aquifer were assessed for sustainability during the 2021–2022 hydrological period, and it was found that approximately 35% of the aquifer area was classified as unstable, 42% as semi-stable, and only 23% as stable. Overall, the findings demonstrate an intensification of quantitative instability in the Mashhad–Chenaran aquifer, emphasising the need to revise groundwater abstraction practices, control pumping rates and implement continuous monitoring to ensure the aquifer is exploited sustainably.

Seismic risk assessment and zoning in urban environments using spatial multi-criteria analysis: a case study of Manjil, Iran

Manoochehr Mortazavi Chamchali

Situated in northern Iran, Manjil City faces significant seismic risk due to its proximity to active fault systems and its role as a corridor for critical regional infrastructure. Past catastrophic events have emphasised the need for robust spatial risk assessment to mitigate the impact on people, the economy and infrastructure. This study presents a comprehensive seismic risk assessment and spatial zonation for Manjil, employing an integrated multi-criteria evaluation approach that couples Geographic Information Systems (GIS), the Analytic Hierarchy Process (AHP) and fuzzy logic. Risk was modelled as a function of the interaction between seismic hazard potential and spatial vulnerability. Vulnerability indicators, including residential density, land use patterns and critical urban infrastructure, were standardized and weighted using the AHP framework. Our findings suggest that high-density residential areas primarily contribute to urban vulnerability, whereas critical infrastructure components play a disproportionately vital role in emergency response scenarios.. In the hazard assessment, a range of proxies were analyzed, including proximity to faults, fault density, peak ground acceleration (PGA), active tectonic indices, topographic slope, and lithological characteristics. These parameters reveal heightened hazard levels in zones adjacent to active faults. By applying fuzzy membership functions and a gamma operator (γ=0.9), we generated an integrated earthquake risk map, classified into five vulnerability tiers ranging from ‘very low’ to ‘very high’ Spatial analysis revealed four distinct high-risk focal zones within the urban footprint, driven by the convergence of elevated seismic hazards and dense concentrations of residential and critical infrastructure. This research demonstrates the efficacy of the GIS–AHP–Fuzzy integration in providing a reliable, data-driven framework for evidence-based urban planning and proactive seismic risk management in seismically prone areas.