Water Table Aquifer Research Articles

Groundwater monitoring infrastructure: Evaluation of the shallow urban and coastal network in Ōtautahi Christchurch

Study regionŌtautahi Christchurch, New Zealand Study focusUrban shallow groundwater monitoring networks are becoming widespread in New Zealand and globally. A reliable groundwater monitoring infrastructure is important to develop knowledge on water table aquifers in coastal cities like Ōtautahi Christchurch. Previous investigations have shown shallow groundwater vulnerability to salinisation and contamination in urban settings, and shallow groundwater exacerbates flooding from climate change and the impact of rising sea levels. New hydrological insights for the regionFollowing the 2010–2011 Canterbury earthquake sequence, shallow groundwater data acquisition and the establishment of a geotechnical database in Ōtautahi Christchurch provided unprecedented information on subsurface conditions. The installation of the groundwater monitoring infrastructure opened the field of New Zealand-based urban hydrogeological studies, including continuous measurements of groundwater levels. This study presents the hydrogeological context of Ōtautahi Christchurch, provides an overview of seismic impacts on groundwater, and documents the monitoring network’s development. Methods for assessing the monitoring network included field surveys and digital information review. The overall good condition and robustness of the network mean the dataset held by the city and regional councils should be more widely used to benefit the community. Implications for researchers and network asset managers mean that the maintenance and availability of the data should be prioritised. Records from urban shallow groundwater monitoring networks are becoming an essential source of information to manage urban water resources under climate change and sea-level rise conditions.

Paleosol-induced early dolomitization with U[sbnd]Pb age constraints and its implications for fluid pathways in ancient sandstone aquifers

In hydrogeology, a key challenge involves identifying patterns within ancient formations to forecast the distribution of fluid pathways and barriers to permeability, as well as comprehending the palaeohydrological system and its changes over time. This study addresses two main research inquiries concerning fluid flow: firstly, the influence of dolomitization induced by paleosols on flow characteristics, and secondly, the implications for fluid flow pattern distribution in continental sedimentary units. The objectives are pursued through: (1) meticulous, high-resolution measurements of porosity and permeability coupled with well-log data from an outcrop and two boreholes; (2) investigation of petrographic features of diagenetic minerals and their ages using the UPb geochronology system; and (3) an integration of these methodologies to grasp rock properties and fluid flow at a broader scale. Findings suggest that early dolomitization in continental sequences significantly affects fluid flow properties across the basin. The development of paleosols triggered early dolomitization, supported by UPb geochronology evidence. Subsequent groundwater migration along hydraulic gradients, influenced by fluctuations in the local aquifer's water table, facilitated the vertical distribution of dolomitization. Dolomitization occurred in residual pores resulting from initial mineral alteration, early lithifying the sediment and preventing mechanical compaction, thus preserving porosity. During migration events, fluids moved vertically along local faults and horizontally through the dolomitized layers of the formation, which likely remained porous at the time, leading to substantial silica mineralization.

Conjunctive management of groundwater and surface water resources using a hybrid simulation–optimization method

ABSTRACT This study aimed to determine the optimal conjunctive utilization of groundwater and surface water resources in the Halil River basin, one of the most significant study regions in Kerman Province (Iran). Multi-verse optimizer (MVO) and the ANFIS (adaptive neuro-fuzzy inference systems) simulation model, known as the MVO–ANFIS simulation–optimization model, were used for this purpose. Moreover, the optimal exploitation policy for the studied basin was presented. The ANFIS model yielded a coefficient of determination greater than 0.99 in Baft, Rabor, and Jiroft. This model had a high capability to simulate groundwater levels in these three regions. Therefore, the ANFIS model was adopted as the simulation model to predict the aquifer water table in these regions. Regarding the conjunctive utilization of groundwater and surface water resources, the exploitation policy resulting from the MVO–ANFIS simulation–optimization model had a desirable performance by supplying 91.70, 87.75, and 97.58% of the total demands of Baft, Rabor, and Jiroft, respectively. Moreover, results of water system performance indicators, including reliability (82.96, 72.65, 95.07), resiliency (70, 53.47, 80), vulnerability (29.54, 25.64, 17.02), and sustainability (74.24%, 66.10%, 85.78%) in the mentioned regions, respectively, showed the appropriate performance of the proposed model for the simulation–optimization problem.

Multi-criteria groundwater potential zonation using GIS-based fuzzified AHP: Case study of Ondo metropolis Southwestern Nigeria

The study utilized the fuzzy analytical hierarchical process (F-AHP) in the multicriteria decision analysis of seven important hydrogeologic parameters associated with groundwater potentiality/yield. The purpose was to develop groundwater potential map using groundwater potential index values (GWPIV) for Ondo metropolis, Southwestern Nigeria. The hydrogeologic parameters were prioritize and assigned different weights hierarchically according to their level of importance using F-AHP, as aquifer layer thickness (0.05), aquifer layer resistivity (0.04), overburden thickness (0.12), transverse resistance (0.18), transmissivity (0.32), coefficient of anisotropy (0.25), and formation factor (0.03). From regional perspective, based on drainage basin, and river network, the region was categorized to be of low/moderate groundwater yield, with moderate to high flow connectivity. The higher and lower elevations are generally remarkable in the northern and southern areas respectively, hence possibility of movement of water towards the southern part with the northern forming the watershed. Furthermore, the longitudinal unit conductance recorded regional average value of 1.168, while 1.20, 1.16, and 1.10 were recorded for granite, gneiss and migmatite, which suggests moderate vulnerability to contamination. The average values recorded for overburden thickness, hydraulic conductivity, transmissivity, transverse resistance, formation factor, coefficient of anisotropy, fracture contrast, and reflection coefficient are 22.5 m, 0.33 m/d, 5.56 m2/d, 4966 ohm-m2, 2.42, 1.17, 15.3, and 0.66 respectively. The water table aquifer and the fractured basement are the major water bearing units in the area; while the geological units showed overlapping hydrogeologic properties. The obtained GWPIV ranged from 1.21 to 3.55 with regional average of 1.86, suggesting a moderate potential. Nevertheless, the southern part showed more propensity/yield than the northern area. The study showed the importance of geospatial mapping technique, involving fuzzy analytical hierarchical process, in groundwater evaluation, as it was able to solve and obtain different hydrogeological parameters, which were integrated to prioritize and define the area's groundwater prolificacy for the purpose of improving, expanding, and management of the existing water scheme in the study area.

Groundwater vulnerability assessment in central Iran: Integration of GIS-based DRASTIC model and a machine learning approach

The study try to evaluate the susceptibility of groundwater. The DRASTIC model was implemented through GIS. Various input variables, such as water table depth, net recharge, aquifer and soil media, topography, vadose zone impact, and hydraulic conductivity, were evaluated within the model to generate a groundwater vulnerability map. Subsequently, machine-learning algorithms (SVM, RF, and GLM) employed using the SDM package in R software to optimize the DRASTIC method. To assess the performance of groundwater pollution risk models, training and validation datasets were evaluated using the ROC curve. The results revealed that approximately 40% of the study area fell within the high vulnerability range, while around 30% exhibited moderate pollution risk. Evaluation of the machine learning models indicated their effectiveness in model development. The RF model demonstrated the highest predictive power, achieving an AUC of 0.98. Additionally, the GLM and SVM algorithms achieved AUC values of approximately 76%. These algorithms can serve as efficient techniques for evaluating and managing groundwater resources. The findings underscored relatively poor groundwater quality in the study area, with excessive aquifer exploitation by the agricultural sector and infiltration of urban sewage and industrial waste identified as the primary causes of groundwater pollution. The implications of these findings are crucial for devising strategies and implementing preventive measures to mitigate water resource vulnerability and associated health risks in central Iran.

Groundwater Prediction Analysis for Sustainable Development in Okeigbo, Southwestern Nigeria: A GIS supported AHP Approach

Multi-criteria decision analysis with GIS-supported Analytical Hierarchy Process (AHP) has been undertaken in Okeigbo, Southwestern Nigeria to predict the hydrogeologic significance of the aquifers and in relation to the geologic units; quartzite, quartz schist, and metadiorite. Six parameters of higher hydrogeologic importance were pairwise and weighted respectively: AQT-aquifer layer thickness (0.07), AQR-aquifer layer resistivity (0.16), OVT-overburden thickness (0.10), TR-transverse resistance (0.20), TMY-transmissivity (0.26), CoA-coefficient of anisotropy (0.22). Subsequently, the GWPIV ranged from metadiorite 1.08 (weathered/fracture aquifer)–quartz schist 3.55 (weathered aquifer) with an average of 2.35 indicating moderate groundwater potential. The low, moderate, and high zones constituted 25%, 55%, and 20% respectively of the study area. The high potential zone is prominent in the mid-central and north central parts. Conclusively, the quartz schist and quartzite areas showed better prolificacy than metadioritic environment. But in terms of protective capacity of the aquifers, the longitudinal unit conductance recorded weak regional average of 0.19396 mhos, with quartzite (0.33444 mhos) and quartz schist (0.15218 mhos); and metadiorite recorded 0.1208 mhos, hence metadiorite being the most vulnerable environment. The water table aquifer and the fracture basement are the major water bearing units in the area. The drainage basin falls within the low–moderate regional drainage basins, with moderate to high flow connectivity and low–moderate flow direction. Thus, there’s possibility of movement of water towards the northern part (discharged zone) with the southern area forming the watershed.

Stories of a water-table: anomalous depressions, aquitard breaches and seasonal implications, Shelby County, Tennessee, USA

An extensive water level survey of the water-table aquifer (i.e., shallow aquifer) within Shelby County, Tennessee, was conducted in the dry (fall 2020) and wet (spring 2021) seasons. Water-table surfaces were generated using cokriging to observe seasonal differences to identify anomalous water-table depressions, indicative of an underlying aquitard breach. Seasonal differences were attributed to non-coincident control and timing between the surveys and when optimum dry (fall) and wet (spring) conditions existed, as observed through comparisons with continuous historical water levels from 12 shallow monitoring wells. Additionally, data from fall 2020 were compared to previous studies in 2005 and 2015 to determine decadal changes in levels and shape of the water-table surface which were mostly attributed to changes in data control and potential climate variations. A prediction error map was generated from the 2020 dataset to identify areas of the county with high-prediction error (>7.0 m) to offer guidance on where future well control would be optimal.

AQUIFER SYSTEMS CHARACTERIZATION FOR GROUNDWATER MANAGEMENT IN ILE-OLUJI, SOUTHWESTERN NIGERIA, USING MCDA GIS-BASED AHP

Multicriteria decision analysis for groundwater potential mapping utilizing analytical hierarchical process of six hydrogeologic parameters including aquifer layer thickness, aquifer layer resistivity, overburden thickness, transverse resistance, transmissivity, and coefficient of anisotropy; in relation to groundwater yield was carried out in Ile Oluji, Southwestern Nigeria. The aim was to develop groundwater potential map using calculated groundwater potential index values (GWPIV). The obtained GWPIV which ranged from 1.53 (granite) – 3.50 (migmatite) with an average of 2.18 suggestive of moderate groundwater potential (90 % of the study area). The low potential zone (10 %) are observed sporadically in the central and northwestern parts. All the geological units recorded overlapping hydrogeologic properties. The longitudinal unit conductance recorded regional average of 0.219876 mhos. Therefore the protective capacity of groundwater system in the study area is weak, and relatively less-weaker in granite environment; and in northwestern and central parts. Nevertheless, the water table aquifer (accounts for 80%) and the fracture basement (constitutes 20%, frequently occurring in gneissic environment) are the water bearing units, with average overburden thickness in migmatite, granite, and gneiss 24.3 m, 24.5 m, and 27.9 m respectively. The average coefficient of anisotropy (1.12); hydraulic conductivity (0.37 m/d), transmissivity 6.86 m2/d (migmatite: 7.17 m2/d, granite: 7.14 m2/d, and gneiss: 6.02 m2/d). Hence gneissic offered both thick weathered layer and fractured aquifer. Empirical model for plot of formation factor and hydraulic conductivity in migmatite, granite, and gneiss, showed positive correlations in descending order as: granite (0.3778), migmatite (0.1057), and gneiss (0.0641).

Serra Geral fractured aquifer and the uncertainties of geospatial models: A case study in the caxias fault zone

In hydrogeology, geospatial interpolators are commonly used to simulate water table distribution, contaminant concentrations and aquifer vulnerability. However, few are the studies that demonstrate which interpolator best suits the dataset. This study targets on this knowledge gap by assessing the geospatial dependency influence, the scale influence and the intrinsic uncertainties of the score over the deterministic and stochastic models in the Serra Geral Fractured Aquifer System. The hydrogeological parameters considered as reference for this assessment were the Potentiometric Surface, Fracture Flow Zones, Static Level, Discharge, Transmissivity and Specific Capacity. The Potentiometric Surface and Fracture Flow Zones parameters have demonstrated a strong spatial dependence on the geomorphology and regional lithostratigraphy, whilst the Static Level, Discharge, Transmissivity and Specific Capacity have showed less spatial dependence and with the worst scores of the consistency indexes. The scale of this study has had little influence on the geospatial models. When using interpolation to generate geospatial models, one should perform an evaluation of the spatial dependency, the mean bias, the shared variance score between observed and simulated dataset and the statistical difference between the scores of the Pearson Correlation prior to choose the most adequate interpolator.

A New Approach for Assessing Groundwater Recharge by Combining GRACE and Baseflow With Case Studies in Karst Areas of Southwest China

AbstractA new approach combining groundwater storage change (GWSC) derived from Gravity Recovery and Climate Experiment (GRACE) satellite data and baseflow was proposed to estimate groundwater recharge at large spatial scales but a short (monthly) time scale. This method was applied in two typical karst basins of southwest China, the Wujiang River basin (WRB, ∼87,900 km2, ∼70% karstification) and Xijiang River Basin (XRB, ∼360,000 km2, ∼44% karstification). The 2006–2012 monthly baseflow was first separated from in situ streamflow through multivariate regression analysis. Groundwater recharge was estimated using separated baseflow and GWSC estimated from GRACE data and observation‐based groundwater‐level data. The comparison between GRACE‐ and observation‐based recharge in the larger XRB shows better consistency, while that in the smaller WRB shows larger discrepancies. Considering the associated uncertainty (60–93 mm/yr), the 2006–2012 mean recharge in two basins, ranging 199–225 mm/yr (17%–19% of precipitation) is comparable to bulletin‐reported estimates (∼145 mm/yr). Both the degree of karstification and aquifer water table depth influence recharge and discharge processes in karst areas of southwest China. The more karstic WRB exhibits more rapid infiltration (due to more developed permeable epikarst zone) and higher discharge capability (due to more developed underground drainage systems), particularly during dry periods (2009, 2011, and winter). Baseflow exhibits a shorter time lag to recharge and GWSC in the XRB than WRB owing to more quick flow, lower storage with more rapid infiltration, and shorter mean groundwater residence time. Observation‐based monthly recharge reflects different rainfall‐infiltration‐runoff processes under different rainfall intensities, particularly in the WRB.

Contribution of GIS for the Piezometric Monitoring of the Unconfined Water Table Aquifer of the Fez-Meknes Basin

Contribution of GIS for the Piezometric Monitoring of the Unconfined Water Table Aquifer of the Fez-Meknes Basin

Using USGS Program WTAQ and Superposition to Model Stream Depletions.

Concerns about streamflow depletions due to groundwater pumping have stimulated the development of various analytical and numerical approaches to quantifying such depletions. Absent among the analytical approaches are those applicable to problems involving a three-dimensional aquifer with a partially penetrating production well. The U.S. Geological Survey program WTAQ can be used to simulate water-level declines in a three-dimensional aquifer without a stream. However, by applying the principles of superposition, WTAQ is used to simulate temporal streamflow depletions due to pumping from a partially penetrating well in a homogeneous, three-dimensional, horizontally infinite, water-table aquifer with an arbitrarily located infinitesimally thin stream positioned vertically at the water table.

Integrated hydrogeophysical and GIS based demarcation of groundwater potential and vulnerability zones in a hard rock and sedimentary terrain of Southern India

This research has identified the groundwater potential and vulnerability zones in Tiruchirappalli district of Tamil Nadu, India. The Schlumberger electrode array has been used to conduct vertical electrical sounding (VES) at 95 sites with a maximum electrode spacing of 150 m. The study area comprises of hard rock and sedimentary formations. Geographical Information System (GIS) has been used to integrate the geoelectrical data and to prepare spatial variation maps for various parameters. Finally, groundwater potential and vulnerability zones have been demarcated, and these outputs have been validated using water level and nitrate data, respectively. The Dar-Zarrouk parameters such as longitudinal conductance (S), transverse unit resistance (T), and aquifer anisotropy (λ) have been used along with the spatial variation of resistivity and aquifer thickness to find out groundwater potential areas with the support of GIS. The thickness of topsoil, weathered zone and fractured zone are not uniform in the research area. Top soil plus weathered zone acts as a water table (phreatic) aquifer, which extends up to 38 m from the surface. Fractured zone extends up to 45 m, which acts as a kind of confined/semi-confined aquifer. Open and bore wells have been constructed to tap groundwater from the unconfined (water table) and confined/semi-confined aquifers, respectively. High to very high groundwater potential areas are associated with low resistivity, high thickness, low longitudinal conductance, high transverse unit resistance and high aquifer anisotropy areas. Very high groundwater potential areas are mostly confined to flood plain (alluvium) deposits in the central portion of the study area. High potential areas are noticed in the northern part, whereas low potential areas are noticed in the southern part. The areas with high longitudinal conductance indicate low permeable zones with less possibility of external pollution. Since agriculture is an important activity in the study region, this work will be useful to provide water supply for irrigation as well as for domestic needs.

HYDROGEOLOGY OF FRACTURED AQUIFERS: APPLICATION OF CONSISTENCY INDEXES FOR THE VALIDATION OF GEOSPATIAL MATHEMATICAL MODELS

In hydrogeology, most studies using interpolators seek to estimate water table elevations, contaminant concentrations and aquifer vulnerability. The primary goal of this research was to evaluate which geospatial interpolator best suits six distinct hydrogeological parameters using nine consistency tests. Water wells were selected on a portion of the Serra Geral Fractured Aquifer System in Southern Brazil. This paper tested the Inverse Distance Weighted, Radial Basis Function, Ordinary kriging, Lognormal kriging and Cokriging methods. The results pointed out that the Inverse Distance Weighted showed better performance for the following parameters: potentiometric surface, first fracture flow zone and second fracture flow zone. Discharge, transmissivity, specific capacity and static level showed low consistency levels, greatly increasing the uncertainties associated with mathematical models for such parameters. Deterministic interpolators surpassed the stochastic interpolators in parameter estimates that presented strong spatial dependence and associations with lithostratigraphy and geomorphology. This research can contribute to future work on groundwater management and planning in fractured aquifers, since the use of different interpolation and consistency approaches to analyse and compare different hydrogeological parameters in a fractured aquifer system has not been found in the literature.

Groundwater Vulnerability Assessment in the Metaponto Coastal Plain (Basilicata, Italy)

This study aims at a groundwater vulnerability assessment of the Metaponto coastal plain, located in the Basilicata region (southern Italy). In the last century, intensive agriculture, zootechnical and industrial activities have significantly changed the plain. These changes led to negative impacts on the hydrogeological system intensifying the risk of the aquifer to pollution. The paper presents the assessment of the intrinsic vulnerability of the coastal aquifer carried out by the GIS-based application of the SINTACS method. It considers several aquifer parameters such as water table depth, effective infiltration, unsaturated conditions, soil media, aquifer media, hydraulic conductivity and topography. Furthermore, the anthropogenic influence in the study area was considered by applying the SINTACS-LU method, in which the parameter of land use (LU) was added. The SINTACS and SINTACS-LU vulnerability indexes were provided by summing the product of ratings and weights assigned to each parameter. The analysis of the intrinsic vulnerability map allowed for determining three classes ranging from low to high vulnerability. In both cases, the southeastern part of the coastal plain, closest to the sea, shows the highest vulnerability class, indicating that it is the most vulnerable to contamination due to the hydrogeological intrinsic factors. The wide central part of the study area shows a moderate class of vulnerability and the low class is scattered in small parts in the northern portion of the plain, which represents the areas less contaminable in space and time in the case of potential pollution. In the SINTACS-LU map, some areas classified as highly vulnerable in the SINTACS method show a minor vulnerability class. These areas are localized in natural and wooded sectors of the Metaponto plain, which are less populated, where human impact on the groundwater is minimal.

Simulating the effect of injection well on groundwater table in unconfined aquifer using numerical model of isogeometric analysis and optimization of injection rate with PSO algorithm

Currently, one of the solutions to improve the decline in the water table of aquifers owing to their uncontrolled extraction is artificial recharge schemes, especially in arid and semi-arid regions. The present study applies a nonuniform rational B-spline functions (NURBS) based isogeometric method to investigate the effects of an injection well on the rise of water table, unconfined aquifer hydrodynamic parameters and injection rate. Also, the best injection rate was determined by linking the isogeometric analysis (IGA) simulation model to the particle swarm optimization (PSO) model. Initially, the IGA method was implemented to simulate a water table over an unconfined aquifer with two extraction wells with discharges of 1142.85 and 1428.57 m 3 day −1 for 210 days and was compared with the Modflow model. The model was tuned and run by constructing an injection well with 8214.28 m 3 day −1 injection rate for 1500 days. The IGA simulation results with ME = −0.0096, MAE = 0.0111 and RMSE = 0.0146 indicated the accuracy of the model in water table simulation compared with the Modflow model with ME = −0.0188, MAE = 0.023 and RMSE = 0.0284. The findings revealed that the use of an injection well has a positive impact on raising the water table, with a rise of 1.24 m in the observation well. Investigating the effect of the parameters on the water table changes indicated that the injection rate directly affects changes in the water table. The water table rises by more than 43% with a 50% increase in the injection rate. Also, compared with the effect of the injection rate on the water table, the transmissivity and specific yield effects were not substantial. The results of IGA–PSO showed that the best value of injection rate is 2000 m 3 day −1 , whereby the aquifer water table rises by an average of 37.12 cm.

Groundwater vulnerability assessment using SINTACS model and GIS: A case study in Raipur city

The purpose of this study is to evaluate groundwater contamination vulnerability in the Raipur region using a Geographic Information System (GIS) based model. Researchers have worked on this method in the past, but none attempted to apply this method to the Raipur region. Various hydrogeological layers of the model i.e., water table depth, unsaturated conditions, soil media, net recharge, topographic slope, aquifer media, and hydraulic conductivity have been weighted as well as classified, integrated into the GIS environment to obtain groundwater contamination vulnerability zones (GVI). The (VI) estimated ranges between 84 to 215. Furthermore, the outcome shows that 5.42% of the region shows very low vulnerability and 14.26% of the region indicates very high vulnerability. Groundwater samples of ten locations were obtained from the delineated groundwater vulnerability zones to validate the model outcomes. The nitrate concentration was observed in the low groundwater vulnerable zone is < 15 mg/l, whereas it ranges from 15-40 mg/l in the moderate groundwater vulnerable zone and more than 40mg/l in the highly vulnerable zone of groundwater. The model approach SINTACS vulnerability index (SVI) is found to be well correlated with the nitrate concentration of the region and is appropriate for GVA of Raipur city. This model approach implemented was therefore found to be efficient for the area’s prevailing hydrogeological settings.

Quantifying natural recharge characteristics of shallow aquifers in groundwater overexploitation zone of North China

To improve the accuracy of hydrological simulations in the groundwater overexploitation zone of North China, it is necessary to study the characteristics of shallow aquifer recharge on daily scale. Three shallow aquifer recharge indices were used to quantify shallow aquifer recharge in two ways. The recharge coefficient was used to quantify the amount of shallow aquifer recharge. The recharge duration and water table rise coefficient were used to quantify the recharge temporal process. The Spearman rank correlation coefficient and regression analysis were used to determine the relationships between aquifer water table depth (WTD), rainfall, and shallow aquifer recharge. The Jiangjiang River Basin, a tributary of the Haihe River, was selected as the study area. The results showed that the recharge coefficient first increased, then decreased, and finally leveled off as WTD increased. When WTD was between 5 and 6 m, the recharge coefficient reached its maximum (approximately 0.3). When WTD was greater than 10 m, the recharge coefficient remained stable (around 0.12). With regard to the sources and forms of recharge, preferential flow was dominant in the areas near the extraction wells. In contrast, plug flow became dominant in the areas distant from the wells. With the reduction of rainfall duration, the proportion of preferential flow contributing to aquifer recharge increased. With the increase of rainfall amount, the duration of aquifer recharge lengthened.

Geomorphological Hazard in Active Tectonics Area: Study Cases from Sibillini Mountains Thrust System (Central Apennines)

In many areas of the Umbria-Marche Apennines, evident traces of huge landslides have been recognized; these probably occurred in the Upper Pleistocene and are conditioned by the tectonic-structural setting of the involved Meso-Cenozoic formations, in a sector of the Sibillini Mountains (central Italy). The present work aimed to focus on a geomorphological hazard in the tectonic-structural setting of a complex area that is the basis of several gravitational occurrences in different types and mechanisms, but nonetheless with very considerable extension and total destabilized volume. An aerophoto-geological analysis and geomorphological survey allowed verification of how the main predisposing factor of these phenomena is connected with the presence in depth of an important tectonic-structural element: the plane of the Sibillini Mountains thrust, which brings the pre-evaporitic member of the Laga Formation in contact with the Cretaceous-Eocene limestone lithotypes (from the Maiolica to the Scaglia Rosata Formations) of the Umbria-Marche sedimentary sequence. Another important element for the mass movements activation is the presence of an important and vast water table and related aquifer, confined prevalently by the different structural elements and in particular by the thrust plane, which has acted and has continued to act, weakening the rocky masses and the overlaying terrains.

Physicochemical characterization of the unconfined water-table aquifer of the Fez-Meknes basin

This paper aims to determine the hydrogeochemical characteristics of the Fez-Meknes free water table thought the monitoring of the physicochemical analyses of nine samples during the year of 2013, 2016, and 2019. This water table, which circulates in the plio-quaternary formations, is generally supplied by rainfall infiltration, irrigation water returns and also the lateral inflow of the unconfined liasic water table of the Middle Atlas Tabular. Analyses were performed for electrical conductivity (EC), potential hydrogen (pH), temperature and major elements: Cl-, NO3-, SO42-, Na+, Mg2+, Ca2+, HCO3⁻, K+. The results of the projection of the samples on the Piper diagram for the three companies showed a hydrochemical carbonate, calcic and magnesian facies for the majority of the samples with the exception of samples 1161/15 and 352/21 for the year 2013. Then, to understand the origin of the mineralization, as well as the processes related to the dissolution of the carbonate country rock, a principal component analysis (PCA) was performed.