Hydrogeological Model Research Articles

New hydrogeological results on the Groundwater Dependent Ecosystem of the Pilato Lake (Sibillini Mts, Central Italy)

Located at an altitude of about 1950 m a.s.l. in a glacial cirque of Mount Vettore (Monti Sibillini National Park - Central Italy), Pilato Lake is one of the few glacial lakes existing in the Apennines. Due to the endemic presence of the crustaceous Chirocephalus marchesonii, the Pilato Lake was in the past mainly studied from the biological viewpoint, but hydrogeological information on this groundwater dependent ecosystem is scarce. Furthermore, for investigating the lake drying in the recent 2017, 2019 and 2020 summers, the seasonal lowering of lake levels during 2010, 2012 and 2014-2020 was reconstructed. It resulted that in the preseismic years, the lake emptying was slower than in the post-seismic time. It is then supposed that seismic quaking induced an increase in permeability and, consequently, increased infiltration velocity through the lake sustaining surficial (detrital and glacial) and/or bedrock deposits towards the subsurface. More frequent summer dryings of the lake are then supposed for the next future. The hydrogeological conceptual model of the study area showed that the refilling process of the lake is driven by snow and rain precipitations. The air temperatures during 2017-2020 and their effects on evaporation from lake and on actual evapotranspiration were estimated. The infiltration through sustaining sediments was calculated and the estimation with time of lake wet surface and lake volume variations, and then bulk permeability of sustaining sediments, were evaluated as well.

Delineating the groundwater protection zone (GPZ) around a water supply plant in Bekasi, West Java, Indonesia

The escalating community demands for water supply in urban areas lead to overexploitation on groundwater and worsening the condition of the resources. These exploitation activities will affect the quality, quantity, and continuity (QQC) of groundwater, especially those that are produced as the resource for the water supply industry. The study area is a water supply industry plant located in Bekasi, West Java, Indonesia, that uses groundwater originating from the Bekasi–Karawang Groundwater Basin. Proper management is needed to maintain the QQC of the groundwater, and one of the steps in pursuing it is with the Groundwater Protection Zone (GPZ) delineation. The aim of this study is to delineate the GPZ in the study area based on the natural conditions and the conceptual hydrogeological models. The method used to delineate the GPZ is groundwater flow modelling. As a result, this study identifies the unconfined and confined aquifers systems at the plant, while the groundwater extraction is only sourced from the confined aquifer. Our findings reveal that the groundwater in both unconfined and confined aquifers generally flows in a south-north direction with the travel time varying from 25 days to 133 years. The GPZ resulted for the water supply plant consists of the production well protection zone and the recharge area protection zone. This study also suggests recommendations for groundwater management in the GPZ based on the source of contaminants.

A high precision finite-element forward solver for surface nuclear magnetic resonance incorporating conductivity changes and surface-topography variations

Surface nuclear magnetic resonance (SNMR) is a geophysical method that can be used directly for detecting groundwater resources, and it has attracted the attention of many scholars. In this paper, we propose a new effective algorithm for numerical modeling of 3D SNMR data for arbitrary topography in a conductive medium. We adopt a total-field algorithm for solving the quasi-static variant of Maxwell’s equation and handle a complex-shaped loop source by discretizing the transmitter into electric dipoles, which can be further easily discretized into electric dipoles along the three directions of the Cartesian coordinate system. To solve the 3D SNMR forward-modeling problem quickly and accurately, a new element-integration system based on a new symmetric orthogonal rule is used for calculating the sensitivity (i.e., kernel) functions of all elements. The new rule is based on a special arrangement involving a cubic close-packed lattice structure and is characterized by fast convergence, positive weight, and symmetry. We apply the developed numerical algorithm to SNMR tomography of several typical hydrogeological models. The synthetic results show that higher precision can be achieved with few grids and nodes without increasing the computation time by using the new integration algorithm. In addition, we find that the topography and conductivity can affect the SNMR response, which needs to be considered while interpreting SNMR data.

Improving spatial characterization of buried bedrock valleys through airborne frequency-domain electromagnetic, residual magnetic, and surface resistivity measurements

The development of a three-dimensional (3D) hydrogeologic site model requires detailed knowledge of an area's hydrostratigraphy, information typically obtained from core logs, historical well records, outcrop mapping, and/or surface geophysics. Due to the high cost of drilling, a 3D model may rely on various statistical techniques to interpolate lithological boundaries between points located tens of kilometers or more apart. This situation can result in poorly constrained or simplified lithostratigraphic models, with under-sampled features such as karst and buried bedrock valleys. The non-invasive nature of airborne geophysical surveys combined with its dense sampling capability can fill critical data gaps. This study evaluates the capacity of a helicopter borne frequency-domain electromagnetic (FDEM) and residual magnetic survey using the Resolve™ system over a buried bedrock valley incised in a multi-layered dolostone aquifer within a complex glaciated environment in an urban/agricultural region of southern Ontario, Canada. The resulting airborne data was evaluated against two high-resolution ground-based electrical resistivity transects oriented orthogonal to the valley, alongside a published Quaternary geological model. A comparison between our local geophysically-based model and the regional geological model shows that the airborne electromagnetic surveys can markedly improve characterization of bedrock valley morphology and Quaternary sedimentary unit architecture that is comparable to that obtained using high-resolution surface-based electrical resistivity measurements with 10 m electrode spacing. The scale of heterogeneity that can be resolved by the airborne survey reveals the level of petrophysical variability that can be seen within the valley infill. Our study demonstrates the potential of airborne FDEM surveys in semi-urban agricultural environments where detailed characterization of Quaternary sediment architecture and bedrock topography is needed to inform 3D groundwater flow system variability.

Aquifer characterization and hydrogeological modeling for devising groundwater management strategies for the Chennai aquifer system, southern India

Aquifer characterization and hydrogeological modeling for devising groundwater management strategies for the Chennai aquifer system, southern India

Groundwater Storage Analysis Using Deterministic Model Approach for Water Resources Management of Zamfara part of Sokoto-Rima Basin, Nigeria

The study area is entirely located within the Sokoto-Rima hydrological basin of Northwest, Nigeria. Groundwater is widely used for drinking, domestic and agricultural purposes in Zamfara water catchment. The mismanagement of groundwater resources could cause negative effects including depletion of aquifer storage and groundwater level decline. To assure sustainability of the available resources, determination of groundwater budget is necessary. Deterministic model approach was used, which required three quantities (Available water quantity, Abstractible and Storable water volume). In this study meteorological water budget (MWB), water level fluctuation (WTF), and groundwater budget based on geological framework (GBBDF) were used to estimate water budget. Groundwater recharge and abstraction rate were calculated from 280 borehole data across the water catchment area. The average groundwater budget of the study area was calculated as 111,693,470 m3/year with the MWB method and it was calculated as 111,342,057.3m3/year and 73,463,099 m3/year with the WTF and (GBBDF) methods respectively. The groundwater abstraction for domestic/agricultural uses was calculated to be higher to that of aquifer recharge. Thus prudent measure has to be adopted for adequate water use per head as population increase and demographic change will exacerbate more stress on the availability of this precious resources aside the climate change impact. The implication is that further proliferation of borehole wells will deplete the entire aquifer and subject it to be devoid of manageable storage capacity, particularly in the crystalline aquiferous units. It is clear that, if conceptual hydrogeological modelling of the catchment is well known and reliable data are obtained, the MWB method gives accurate results in the basins. However, comparison of multiple methods is valuable for determining the plausible budget amount and for highlighting the uncertainty of the estimate.

Glacial Melt in the Canadian Rockies and Potential Effects on Groundwater in the Plains Region

The prevailing concern in the Western Canadian Plains is that glaciers from the eastern Canadian Rocky Mountains (CRM) are losing mass, thus affecting groundwater recharge in the Plains. The generally accepted hypothesis is that those glaciers are the geological source of groundwater for aquifers located in the Plains. The aquifers located in this region, close to the eastern part of the Rockies, represent a major source of water for the local population. It is believed that aquifer recharge originates as infiltration from snowmelt and ice in the Front Ranges of the eastern Rockies. A growing concern relates to the significant glacier melt estimated from glacier mass balances, which indicate that glaciers and ice fields have experienced considerable mass losses over the last 15 years, between 1 and 5 km3 per year, thus reducing recharge. However, deep groundwater flow under melting glacier conditions in mountainous regions is poorly understood. In this study, three 2D numerical hydrogeological models are built in order to simulate the groundwater flow under the glaciers from the Main and Front Ranges of the CRM and the Plains in the province of Alberta, Canada. Numerical results and a sensitivity analysis indicate that up to three different regional groundwater-flow systems are present in the region. These systems reveal the time- and space-scales associated with the combination of a mountainous region, foothills, Plains, and deep geological conditions. Based on the current knowledge of the hydrogeology of the study area and numerical modelling results, it is highly unlikely that the melting of glaciers affects groundwater in the Plains in the immediate future. The contribution of glacier water in the eastern part of the Rockies is time-dependent with delayed groundwater flows of 1000s of years in the Front ranges, 1000s to 100,000s of years in the foothills and Foreland; and 100,000s to millions of years to the Plains, at the regional scale.

Uncertainty of heterogeneous hydrogeological models in groundwater flow and land subsidence simulations – A case study in Huwei Town, Taiwan

The distribution of hydrogeological materials in a three-dimensional heterogeneous aquifer system has a large effect on groundwater flow and land subsidence simulations. The hydrogeological information for regions between boreholes embeds a large amount of uncertainty into the hydrogeological model, and thus affects numerical assessment. Quantifying the effects of the heterogeneous system and hydrogeological model uncertainty on groundwater flow and land subsidence simulations is thus important. Here, data from 46 geological boreholes in Huwei Town, Taiwan, were adopted to investigate hydrogeological model uncertainty. The one-dimensional continuous-lag Markov chain and the geostatistical method were used to analyze the spatial characteristics of hydrogeological materials and generate realizations of the hydrogeological model based on the assessment results. Estimated hydrological conditions and hydraulic parameters were applied to mitigate uncertainty not caused by the hydrogeological model. The mean of the results of land subsidence in Monte Carlo simulations showed a more stable distribution than that of individual realizations, for which land subsidence might be far from the mean. Therefore, the mean and variance results provide a reliable assessment with uncertainty information for land subsidence simulations. The coefficient of variation (CV) was used to quantify the hydrogeological model uncertainty. The CV value of land subsidence was larger than that of the hydraulic head because the thickness of clay is not uniform whereas the flow pattern is smooth. The variance and CV distributions of the hydraulic head and land subsidence provide uncertainty information that can be used to guide site investigations. A heterogeneous hydrogeological model with uncertainty quantification should be carefully applied to land subsidence simulations to obtain reasonable results.

Three-dimensional hydrogeological modeling method and application based on TIN-GTP-TEN

Three-dimensional hydrogeological modeling method and application based on TIN-GTP-TEN

The Cauê Aquifer on the eastern limb of the Moeda Syncline: characterization, impacts, and flow in the western Iron Quadrangle (Quadrilátero Ferrífero), MG, Brazil

The Cauê Aquifer is an important water supplier to the third largest urban agglomeration in Brazil. The Metropolitan Region of Belo Horizonte is in the Iron Quadrangle, site of intense iron ore mining, requiring large volumes of water and mine dewatering. In this context, we evaluate the regional impact on groundwater level between 2000 and 2019 based on a conceptual hydrogeological flow model on the eastern limb of the Moeda Syncline. This study includes the definition of boundary conditions and aquifer units, the calculation of hydrodynamic parameters, water balance, renewable reserve, and flow analysis. The Cauê, Gandarela, and Moeda aquifers are considered aquifer units, among which the Cauê Aquifer showed the highest hydraulic conductivity (9.45×10-7 m/s on average) as well as the highest recharge rate, with 38.67% rainfall. The average volume pumped was estimated at 41 million m³/year, equivalent to about 150% of the renewable reserve of the Cauê Aquifer, calculated at 27 million m³/year. Underground flow in the area tends southward, and the Cauê Aquifer acts as a water divide, which is less evident in the center of the area, where the greatest impact on groundwater level lowering occurs.

Impact of the closure of a coal district on the environmental issue of long-term surface movements

<abstract> <p>The environmental impact of deep underground coal mines using the longwall mining method is diverse, e.g., short- and long-term subsidence, damage to surface infrastructure, disturbance of the hydrogeological conditions, and the quality of groundwater and surface water. The study presented focusses on the long-term surface movements after the closure of an entire coal district. Due to the flooding of the underground infrastructure and rock mass, an upward surface movement or uplift is observed. For a specific site in the Campine coal district, Belgium results are presented of satellite data (radar-interferometry). However, the main aim of the study is to better understand the process of uplift and to determine the various mechanisms that are involved. For this purpose, an analytical framework was developed recently, and it was applied successfully in a relatively easy case. The case study of the paper is more challenging, but the usefulness of the analytical framework is clearly confirmed. The most important conclusions are that (i) the uplift is induced by an increase in water pressure after the closure, i.e., re-establishing the original hydraulic gradient, (ii) the expansion of both the goaf volumes and the volumes of the non-collapsed rock mass must be considered, and (iii) the assumption of a linear decrease of water pressure variation from the top to the bottom of the mined area at the end of the mining phase provides the most realistic results. However, the next step in the analysis should focus on a more advanced hydrogeological model of the complex underground environment.</p> </abstract>

ОБҐРУНТУВАННЯ МЕТОДИКИ ОЦІНКИ ГІДРОДИНАМІЧНОГО ТА ГЕОМЕХАНІЧНОГО ВПЛИВУ ГОЛКОФІЛЬТРОВИХ УСТАНОВОК

Purpose. The purpose of this work is to develop and test the methodology for determining changes in the level of groundwater over time as a result of the operation of several contours of needle filters of different configurations and the impact of these changes on the subsidence of the earth’s surface. Methods. The proposed comprehensive approach includes the collection, systematization and analysis of data on the existing methods of calculating the subsidence of the earth’s surface at the base of structures in the event of an expected decrease in the level of groundwater. The method of numerical hydrogeological modeling and analytical calculations was used to determine the magnitude of the decrease in the groundwater level and subsidence of the earth’s surface. Findings. According to the results of numerical modeling of geofiltration, it was established that after the second month of operation of the first circuit of needle filters, the groundwater level mark at a distance of 20 m from them is 50.4 m, at 50 m – 51 m, at 100 m – 51.6 m. the main decrease of water occurs in the first 7 m from the drainage circuit and is 6.35 – 3.8 m. After 6 months of operation of the first circuit and 4 months of the second water level mark at a distance of 20 m from the circuit is 46.7 m, at 50 m – 47.8 m, at 100 m – 48.9 m. This, respectively, leads to a decrease in the level at these points by 6.8 m, 5.7 m and 4.6 m. it was established that in the first 100 m from the pit, soil subsidence at the end of operation of the two needle filter circuits will vary from 3.9 cm to 2.6 cm. Originality. The method of determining changes in the groundwater level as a result of the operation of several needle filter circuits and the impact of these changes on the subsidence of the earth’s surface has been substantiated and verified. The developed technique allows to analyze and preliminarily quantitatively assess the hydrodynamic regime and geomechanical state of rocks under the influence of needle filters. Practical implication. The proposed method can be used for engineering forecasts of subsidence of the earth’s surface during water-reduction works with needle filter installations, which is especially relevant in the conditions of built-up areas. Keywords: drainage, needle filters, groundwater, earth’s surface, subsidence.

Расчетные коды для гидрогеологического моделирования в задачах оценки безопасности ОИАЭ

The paper analyzes modern trends in the development and use of software systems for three-dimensional hydrogeological modeling. It provides an analytical overview of most recent and widely used software products, their development process, the implemented models and the numerical methods applied. The study specifies a range of typical tasks addressed by Russian nuclear industry requiring the development of numerical geofiltration and geomigration models. To demonstrate the use of modern computational technologies, studied was the case involving calculations in the GeRa software package performed for LRW DDF. The paper identifies the trends for further software evolution taking into account the Russian needs in the development of near-surface and deep RW disposal facilities, decommissioning, as well as the accumulated experience in the operation of RW storage facilities and global trends in the code development.

How groundwater time series and aquifer property data explain heterogeneity in the Permo-Triassic sandstone aquifers of the Eden Valley, Cumbria, UK

A novel investigation of the impact of meteorological and geological heterogeneity within the Permo-Triassic Sandstone aquifers of the River Eden catchment, Cumbria (UK), is described. Quantifying the impact of heterogeneity on the water cycle is increasingly important to sustainably manage water resources and minimise flood risk. Traditional investigations on heterogeneity at the catchment scale require a considerable amount of data, and this has led to the analysis of available time series to interpret the impact of heterogeneity. The current research integrated groundwater-level and meteorological time series in conjunction with aquifer property data at 11 borehole locations to quantify the impact of heterogeneity and inform the hydrogeological conceptual understanding. The study visually categorised and used seasonal trend decomposition by LOESS (STL) on 11 groundwater and meteorological time series. Decomposition components of the different time series were compared using variance ratios. Though the Eden catchment exhibits highly heterogeneous rainfall distribution, comparative analysis at borehole locations showed that (1) meteorological drivers at borehole locations are broadly homogeneous and (2) the meteorological drivers are not sufficient to generate the variation observed in the groundwater-level time series. Three distinct hydrogeological regimes were identified and shown to coincide with heterogeneous features in the southern Brockram facies, which is the northern silicified region of the Penrith Sandstone and the St Bees Sandstone. The use of STL analysis in combination with detailed aquifer property data is a low-impact insightful investigative tool that helps guide the development of hydrogeological conceptual models.

ArcFem: New Software Module in ArcGIS for Numerical Modeling

The numerical modeling of physical phenomena has become for many users a necessity. It allows both a better understanding of the studied system and a better link with the purpose and policy makers. We discuss mathematical models, which attempts to represent the physical phenomenon of groundwater flow by mathematical expressions using different software to facilitate the design models. Coupled with GIS software model has become possible, through a database synthesized to introduce geographic data such as boundary conditions, wells, recharge areas, who see themselves as the fuel of the model, but the role of this software is limited to a part in the preparation of data for use in software hydrogeological modeling and secondly, in view of the results obtained by them, hence the need for a customized GIS application. The user of GIS in the field of hydraulic modeling groundwater is brought to the exercise of his profession to reproduce a large number of both transactions; similar processing where it needs personalized treatments. The automation of these processing in the ArcMap environment using Java ArcObjetcs and has led to significant time savings and ease in handling input data and output results.

Lumped geohydrological modelling for long-term predictions of groundwater storage and depletion

Excessive groundwater pumping exacerbates aquifer depletion and poses a major threat in regions all around the world that already suffer from overuse or climate change. In this situation, accurate and reliable predictions of long-term aquifer water balances are key prerequisites to manage groundwater sustainably. Compared to spatially explicit numerical models, lumped hydrological models are computationally fast, lean on data requirement and more accessable for quantifying uncertainty. However, lumped hydrological models are mainly designed to simulate river discharge only, not aquifer storage. Consequently, calibration only includes stream flow data. In this study, we hypothesize that we can extend a lumped hydrological models (here HBV) towards a lumped geohydrological model (LGhM) by additional, designated terms for water budget and groundwater storage. The model building is inspired by the geometry and hydrogeological large-scale properties of the catchment’s aquifers. Underground flow routing resembles major groundwater flow paths. The model is calibrated and evaluated on both groundwater storage data and surface discharge data. We apply our LGhM to a MODFLOW-based virtual reality describing the unconfined Wairau Plain Aquifer, New Zealand. We consider and discuss specifically river-groundwater exchange processes, long-term forecast of aquifer storage dynamics, and groundwater depletion in a hypothetical, persistent drought. Our model evaluation shows very plausible predictive capabilities in 40-year forecasts with synthetic weather time series and several years of groundwater depletion in the extreme drought case.

ON THE RATIONAL USE OF EXPLOITABLE DRINKING GROUNDWATER RESERVES FOR WATER SUPPLY TO THE CITY OF KYIV

The influence of anthropogenic load within the Kyiv field of drinking groundwater has resulted in deformation of the water exchange structure and pattern. The main anthropogenic factors affecting water exchange include groundwater intake structures, reservoirs, as well as urban-industrial agglomerations. The paper presents a critical analysis of the previous hydrogeological models of the groundwater field under study, taking into account their shortcomings and using the most realistic solutions. New up-to-date hydrogeological model of the study area has been created. Simulation modelling was performed to determine the effects of hydrogeological parameters changes on the groundwater level position. Epignostic modelling allowed us to specify transmissivity of aquifers, specific permeability of confining beds and natural groundwater recharge, as well as to prove functional correspondence of the created model to naturalanthropogenic conditions. Exploitable reserves of drinking groundwater for the city of Kyiv were reassessed according to the current request of PJSC “AK” Kyivodokanal” and the potential of groundwater withdrawal was shown. Reserves calculated by method of mathematical modelling were approved by the State Committee of Reserves of Ukraine.

Establishing 3D hydrogeological solid model and database for sustainable groundwater management in the Vietnam Mekong delta

The Vietnam Mekong delta (VMD) is a tide-dominated delta formed by the Mekong river system. The sediments are dominantly fine grained and were deposited in the receiving basin with slight inclination of pre-existing deposits in the East sea and gulf of Thailand. The VMD is homeland to about 18 million people that exploit about 4-6 million m3/day of groundwater mainly for domestic use. In recent years, significant groundwater depletion has been occurring in many parts of the VMD due to excessive pumping. Consequently, the VMD has become increasingly faced with serious land subsidence, salt groundwater intrusion, and contamination. Establishing a 3D hydrogeological solid model and database are sorely needed to achieve sustainable groundwater management, and to serve as a basis for further in-depth analyses to quantify contributions from the above-mentioned hazards to current hydrogeological conditions. Therefore, a 3D hydrogeological solid model and database were built based on more than 1000 well logs available from the VMD. An areal distribution of the Holocene, Pleistocene, Pliocene, and Late Miocene subsurfaces from this 3D hydrogeological solid model and database showed zones of tectonic depression and uplift from Early Miocene - Quaternary. Also, the resulting areal distribution aquitards and aquifers thicknesses gave hints of ground saltwater intrusion and contamination.

From Lithological Modelling to Groundwater Modelling: A Case Study in the Tiber River Alluvial Valley

This study presents the results of a research project financed by the Lazio Regional Government. The research focused on defining an integrated model of recent alluvial deposits in the Tiber River. To achieve this objective, geological boreholes were made to monitor the aquifer and in situ and laboratory tests were carried out. The data obtained were used to detail stratigraphic aspects and improve the comprehension of water circulation beneath the recent alluvial deposits of the Tiber River in the urban area of Rome, between the Ponte Milvio bridge and the Tiber Island. The stratigraphic intervals recognised in the boreholes were parameterised based on their litho-technical characteristics. The new data acquired, and integrated with existing data in the database of Institute of Environmental Geology and Geoengineering of the Italian National Research Council, made it possible to produce a three-dimensional model of the lithologies in the study area. The model of the subsoil, simplified for applied reasons, was described in hydrostratigraphic terms: three different lithotypes were subjected to piezometric levels monitoring. Finally, the research generated a numerical hydrological model in a steady state. In general, this study demonstrates how a numerical hydrogeological model calibrated by piezometric monitoring data can support the construction of a geological model, discarding or confirming certain hypotheses and suggesting other means of reconstructing sedimentary bodies.

A slow and complex landslide under static and seismic action

A dam construction project for the heightening of a dam is threatened by a large landslide located in the Spanish Southern Pyrenees. A marked syncline structure, folding a flysch formation overlying a marl substratum, is the main geological feature of the unstable valley slope. The landslide is characterized by two main and superimposed slip surfaces which follow the bedding layers. The motion observed is very slow and its acceleration can be related to rainfall regimes and changes in loading condition due to excavations.The paper provides an insight into the complexities associated with stability and kinematic evolution of a landslide under static and dynamic actions. Simplified procedures are proposed to predict the complex landslide behaviour. A comprehensive hydrogeological model is developed to relate rainfall history and water pressure which incorporates available data about the anisotropic permeability of flysch and the natural drainage obtained from pumping test and insitu measurements. The stability analysis of the slope focuses on the discussion of safety factors and their practical implication not only in terms of static limit equilibrium, but also on creeping velocity. The latter was evaluated under the simplified assumption of planar landslide and invoking the strain-rate effects on residual strength. A derived analytical expression provides a relationship between Safety Factor and creeping velocity. Under such hypothesis, the increment of the strength required to avoid predicting unrealistic landslide acceleration should be imposed for a lower range of shear velocity than the usual value imposed in the laboratory shearing tests.The seismic response of the landslide is also analysed. A Newmark's approach and a stress-strain finite element (FE) analysis are compared, with special emphasis on the effect of the superimposed slip surfaces on the dynamic landslide response. To do that, the Newmark's analysis has been extended to two overlaying sliding surfaces with independent strength properties and pore water pressure. It is concluded that assuming a single deeper sliding surfaces may underestimate the co-seismic permanent displacement. The comparison of two-block Newmark's analysis with two-dimensional elastoplastic FE approach highlights the effect of geometry in the landslide motion.