Hydrogeologic Units Research Articles

Groundwater dynamics clustering and prediction based on grey relational analysis and LSTM model: A case study in Beijing Plain, China

Study regionBeijing Plain, China Study focusThe traditional zoning of groundwater systems relies on lithological characteristics and hydraulic connections. However, the influence of climate change and human activities has led to the emergence of diverse dynamic patterns within these systems. Additionally, the differences in groundwater dynamic characteristics are often ignored when modeling with machine learning methods. In this study, a new clustering method named GRA-CLU was proposed to classify dynamic types of groundwater. Then, regional models are built using LSTM based on the dynamic zoning, aiming to incorporate hydrogeological significance into the pure data-driven model.New hydrological insights for the region: The GRA-CLU method classified the study area into six groundwater dynamic types. Compared with the traditional hydrogeological units, the new zoning result identified two dynamic types that have never been considered: urban influence zone and mountain-plain junction zone where surface water interacts with groundwater. Through analysis, the significant rise of groundwater levels in 2021 was more influenced by heavy rainfall events rather than human activities. This study further explored the performance of LSTM regional models based on the six dynamic zones. The results indicated that the NSE of models increased by 5.7–50.0 %, the improvement was more obvious in zones with irregular fluctuations. The RMSE decreased by 31.5–59.8 %, particularly noticeable in zones with regular annual fluctuations and large samples.

Effective transboundary aquifer areas between Mexico and the United States: A border-wide approach

Study RegionThis research is situated in the U.S-Mexico border region. It encompasses the geographical extension of the 28 transboundary aquifers located across the ten border states between the two countries. Study FocusThis study aims to identify regions within the hydrogeological units shared across the U.S.-Mexico border that could be in a vulnerable condition due to groundwater overexploitation on either side of the border. The Effective Transboundary Aquifer Area (ETAA) approach attempts to represent those effective geographical areas of groundwater production within the geological boundaries of the aquifer, to prioritize vulnerable areas at a more refined and local scale. To identify ETAAs, this study uses well density well depth data to portray depth contours as a proxy for potential impacts of groundwater flows at transboundary level. New Hydrological InsightsFor planning and management purposes at binational scale and considering the constraints on data and research on transboundary aquifers, the ETAAs provide a more feasible and useful approach to assess the conditions of a shared resource at a more “localized” scale. This approach facilitates the integration of stakeholders’ perspectives and specific needs of the communities that overlay the ETAA. Results show the location and extension of the ETAAs across the complete U.S.-Mexico border identifying the most vulnerable and highly groundwater-dependent regions.

The impact of managed aquifer recharge on the fate and transport of pesticides in agricultural soils

Groundwater aquifers worldwide experience unsustainable depletion, compounded by population growth, economic development, and climate forcing. Managed aquifer recharge provides one tool to alleviate flood risk and replenish groundwater. However, concerns grow that intentional flooding of farmland for groundwater recharge, a practice known as Ag-MAR, may increase the leaching of pesticides and other chemicals into groundwater. This study employs a physically based unsaturated flow model to determine the fate and transport of residues of four pesticide in three vadose zone profiles characterized by differing fractions of sand (41 %, 61 %, and 84 %) in California's Central Valley. Here, we show that the complex heterogeneity of alternating coarse and fine-grain hydrogeologic units controls the transit times of pesticides and their adsorption and degradation rates. Unsaturated zones that contain a higher fraction of sand are more prone to support preferential flow, higher recharge rates (+8 %), and faster (42 %) water flow and pesticide transport, more flooding-induced pesticide leaching (about 22 %), as well as more salt leaching correlating with increased risks of groundwater contamination. Interestingly, considering preferential flow predicted higher degradation and retention rates despite shorter travel times, attributed to the trapping of pesticides in immobile zones where they degrade more effectively. The findings underscore the importance of considering soil texture and structure in Ag-MAR practices to minimize environmental risks while enhancing groundwater recharge. The study also highlights that selecting less mobile pesticides can reduce leaching risks in sandy areas.

A hydrogeophysical conceptual model in the exploration of the "Las Sierras" aquifer: Case of Subwatershed III, southeast sector of Lake Managua, Nicaragua

This study proposes a hydrogeophysical conceptual model in a region southeast of Sub-basin III, which is part of the "Las Sierras" aquifer. The methodology employed combines geological data obtained from wells with geo-electric profiles, thus allowing a more precise representation of an underground valley hitherto unknown, primarily related to the materials of the Middle Las Sierras Group (TQps-M), identified as the main aquifer in the area. The delineation of hydrogeological units was carried out considering geological and geophysical conditions, providing valuable information to understand the distribution and behavior of groundwater in the region. The precise identification and delineation of hydrogeological units enable better management of groundwater resources in the region. This more detailed knowledge enables more effective strategies for the preservation and sustainability of local aquifers.

Strontium isotopes in the atmosphere, geosphere and hydrosphere: Developing a systematic “fingerprinting” framework of rocks and water in sedimentary basins in eastern Australia

Understanding the connection between aquifers, aquitards, and groundwater-dependant ecosystems remains a key challenge when developing a conceptual hydrogeological model. The aim of this study was to develop a systematic strontium isotope (87Sr/86Sr) fingerprinting framework of rocks and water within the sedimentary Surat and Clarence-Moreton basins (SCM basins) in eastern Australia – an area of extensive coal seam gas development and high potential for aquifer and groundwater-surface water connectivity. To do this, new groundwater samples (n = 298) were collected, analyzed and integrated with published data (n = 154) from the basins' major sedimentary, volcanic and alluvial aquifers, including the major coal seam gas target, the Walloon Coal Measures. Samples were also analyzed from rainfall (n = 2) and surface water (n = 40). In addition, rock core samples (n = 39) from exploration and stratigraphic wells were analyzed to determine the range of Sr isotope composition from host rocks. The analyses of cores demonstrate a distinct and systematic contrast in 87Sr/86Sr between different hydrogeological units. This confirms that all major hydrogeological units have a narrow range with unique 87Sr/86Sr population characteristics that are useful for guiding conceptual model development. Comparison with selected hydrochemical and groundwater age tracers (14C and 36Cl) suggests only limited changes of 87Sr/86Sr from recharge beds to the deeper parts of the basins or with a decrease in natural 14C and 36Cl tracer content along flow paths. Stream sampling during baseflow conditions confirms that 87Sr/86Sr in surface waters are similar to those of the underlying bedrock formations. We demonstrated that 87Sr/86Sr analyses of rocks and water provide a powerful hydrostratigraphic and chemostratigraphic fingerprinting framework in the SCM basins, enabling reliable assessments of plausible aquifer and groundwater-surface water interconnectivity pathways. Applied in other complex multi-aquifer sedimentary basins in Australia, and globally, a similar approach can help to constrain conceptual hydrogeological models and facilitate improved water resource management.

Groundwater flow modelling in Neoproterozoic carbonate karst based on dye tracer pathways

The current study consisted of the development of a hydrogeological numerical model in the Lagoa Santa Karst Environmental Protection region, in order to represent the conduit-flow karst springs in the most well-studied karst system in Brazil. Once carbonate aquifers are characterized by a complex 3D pattern with a combination of a double porosity of matrix and conduits, two different modelling approaches were used: Equivalent Porous Medium (EPM), based on Darcy’s law, to represent laminar flow in the fractured massif and Conduit Network (CN), using Manning-Stricker Law and the discrete feature tool, to represent the karst conduits with turbulent flow. Modeling was calibrated in a steady-state and simulations of groundwater flow and an evaluation of water exchanges between the karstic aquifer and the other hydrogeological units, were conducted. The model was developed based on data available for many studies carried out in the area, including tracer-derived route data. The calibration results for spring discharges, water levels and mass balance were satisfactory and aligned with modeling good practices. In turn, the hydraulic conductivities and recharge rates obtained by back-analysis were in agreement with literature references. The regional groundwater flow was well represented and indicated how external water entrances can be relevant to explain the higher discharge rates observed in some karstic springs. In addition, the representation of conduits allowed for the simulation of tracer pathways, enabling the inference of potential flow rates to the karstic springs from the particle simulations.

Geophysical exploration to assess leachate percolation and aquifer protectivity within hydrogeological units at a major open dump in Eket, Nigeria

Leachate contamination was investigated with geo-electrical methodologies at a major open dump in Eket, Southern Nigeria. The open dump is heavily polluted, degrades the environment, and has released toxins into the atmosphere. To model leachate percolation, vertical electrical soundings (VES) and electrical resistivity tomography (ERT) surveys, constrained by well lithological information, were undertaken at the site. The field equipment used for the geo-electrical investigations was the ABEM Terrameter SAS 1000 and its accessories. WINRESIST software was employed to process the sounding data and RES2DINV was employed to generate 2D tomograms indicating subsurface heterogeneity. Results obtained from sounding data showed that the subsurface had three lithological units (motley topsoil, fine sand and coarse sand), with coarse sand being the main hydrogeological unit comprising water-bearing formations. The first layer’s resistivity ranged from 84.9 – 625.4 Ωm with a mean of 360.4 Ωm; the second layer’s resistivity ranged from 7.5 – 1008.1 Ωm with a mean of 142.9 Ωm, and the third layer’s resistivity values ranged from 11.6 – 745.6 with a mean of 205.5 Ωm. The 2D resistivity tomograms indicated that leachate had percolated into groundwater resources. This is concerning as groundwater is the major water resource within the area. Measures of the Dar-Zarrouk indices and electrical reflection co-efficient indicated that the highly heterogenous region had moderate aquifer protective capacity and moderate aquifer potentiality. To mitigate contamination at the site, sanitary landfills, phyto-remediation, impermeable liners, or impermeable earth materials should be employed to diminish the rate of leachate percolation.

Evaluation of geohydraulic response properties of hydrogeological units in Littoral hydro-lithofacies in Uyo, Southern Nigeria

Aquifer geohydraulic response properties are important parameters in groundwater resource management and exploitation. However, geohydraulic properties in the study area is sketchy and due to wildcat drilling. This practice, which leads to inadequate inventory of groundwater parameters, deprived the area of efficient exploitation, monitoring and management of groundwater resources. This study is aimed at evaluating the geo-hydraulic response properties of hydrogeological units in littoral hydro-lithofacies in Uyo, Southern Nigeria. Vertical electrical sounding (VES) technique was carried out, and a total of fifteen geoelectric soundings were obtained using IGIS Resistivity metre model SSR-MP-ATS and its accessories employing Schlumberger electrode configuration. The interpreted data give sets of geoelectric curves from which the aquifer resistivity and thickness were determined. The results reveal the aquifer bulk resistivity ranging from 23.4 to 1306.2 Ωm with an average of 347.99 Ωm, while aquifer thickness spanned from 7.4 to 56.3 m. The formation factor, fractional porosity and transmissivity ranged from 2.41 to 12.52, 0.20 to 0.46, and 0.001 to 0.037m2/s, respectively. The formation tortuosity also ranged from 1.05 to 1.58; longitudinal conductance ranged from 0.020 to 1.004 Ω−1; and transverse resistance ranged from 549.90 to 69,097.98 Ωm2. These parameters were contoured, and their variations are displayed on the contour maps generated. The graphs plotted showed strong correlation coefficient and earth response function that can be used in modelling the aquifer repositories in areas with similar geomaterials. The results of this study indicate that the survey area has a good prospect for groundwater accumulation, and the results can be useful in installing matching hydraulic pumps in boreholes in the survey area.

Development of land use and impact on water resources of hydrogeological unit 4232 Ústecká syncline in the Svitava river basin

Development of land use and impact on water resources of hydrogeological unit 4232 Ústecká syncline in the Svitava river basin

Geomorphometry and aeromagnetometry as water management tools: A case study in hydrological planning units in southeastern Brazil

Proper management of available groundwater and surface water reservoirs plays a crucial role in the sustainable distribution of natural resources in densely populated regions, while also contributing to water security. In this context, the development of straightforward and valuable cartographic interpretations plays a significant role in enhancing the understanding of fractured aquifer dynamics. The aim of this research is to investigate geospatial similarities between geological-geophysical lineaments and well production, with the purpose of determining whether aeromagnetometry and geomorphometry can contribute to the study of fractured aquifers and be utilized as tools in water resource management. Study areas were delineated based on previously defined hydrological units, often used in urban water supply planning. Additionally, geomorphometric structures were identified from a hydrologically consistent elevation model. To explore the potential of available magnetic data, filters were applied to magnetic lineaments, including vertical derivative and analytic signal amplitude. As a result, this study identified at least two productive hydrogeological units within a range of approximately 200 m along magnetic lineaments: 0.47 m3/h/m in granitoids with NNW-SSE and WNW-ESSE trending structures, and 0.27 m3/h/m in gneisses with NW-SE and ENE-WSW trends. These orientations are consistent with Cenozoic tectonic reactivation, and drilling sites located along these lineaments demonstrate higher productivity. Therefore, this study highlights that the integrated application of geophysical, geomorphometric, and hydrodynamic data can significantly improve correlations between subsurface structural configurations and hydrological productivity in fractured reservoirs, while also making a significant contribution to water management.

Electro-sequence valorization of specific enablers of aquifer vulnerability and contamination: A case of index-based model approach for ascertaining the threats to quality groundwater in sedimentary beds

This work was set up to appraise the quality of groundwater within a newly established university using index-based techniques and the intention is to generate vulnerability potential maps that can guide in avoiding vulnerable aquifer systems. The study used geo-electrical technology to evaluate the lithological sequence of the hydrogeological units and their first-and second-order geo-electric properties, as well as the geochemical constituents of groundwater. The results showed that the hydrogeological units are composed of sequences of sands, including fine to gravelly sands minimally laced with sandy clay, according to the results of geo-electrical technology. Layers 2 and 3 were accessible by the twenty VES (V1-V20) in which current gained access to designated economic and prospective aquifer systems. The aquifer systems considered have resistivity values ranging from 26.3 to 3576.5Ωm and mean value of 832.97Ωm. The five vulnerability models deployed showed very high spatial variability and moderate negative and positive binary correlations, construed to be due to subjectivity in the weight-rate assignment. The coefficients of variation (CV) from sensitivity analysis (SA) indicated variation in the vulnerability index due to topography (9.7%) and the impact of the vadose zone (4.3%), which are marginally higher than the 1.6% displayed by other parameters. The groundwater displayed WHO's disallowed concentrations of heavy ions, and the SA indicated that CV for the groundwater geochemical contamination is variably high in cadmium ions (140.9%) followed by manganese ions (132%) and copper ions (88. 2%) across the wells. The moderately variable contribution distributions across the wells are nickel ions (48.8%), lead ions (41.6%), chromium ions (39.8%) and iron ions (35.0%). All the geophysical and geochemical indices affirm that the groundwater is vulnerable and contaminated and therefore requires monitoring and management.

Differentiation of Multi-Parametric Groups of Groundwater Bodies through Discriminant Analysis and Machine Learning

In order to facilitate the monitoring of groundwater quality in France, the groundwater bodies (GWB) in the Provence-Alpes-Côte d’Azur region have been grouped into 11 homogeneous clusters on the basis of their physico-chemical and bacteriological characteristics. This study aims to test the legitimacy of this grouping by predicting whether water samples belong to a given sampling point, GWB or group of GWBs. To this end, 8673 observations and 18 parameters were extracted from the Size-Eaux database, and this dataset was processed using discriminant analysis and various machine learning algorithms. The results indicate an accuracy of 67% using linear discriminant analysis and 69 to 83% using ML algorithms, while quadratic discriminant analysis underperforms in comparison, yielding a less accurate prediction of 59%. The importance of each parameter in the prediction was assessed using an approach combining recursive feature elimination (RFE) techniques and random forest feature importance (RFFI). Major ions show high spatial range and play the main role in discrimination, while trace elements and bacteriological parameters of high local and/or temporal variability only play a minor role. The disparity of the results according to the characteristics of the GWB groups (geography, altitude, lithology, etc.) is discussed. Validating the grouping of GWBs will enable monitoring and surveillance strategies to be redirected on the basis of fewer, homogeneous hydrogeological units, in order to optimize sustainable management of the resource by the health agencies.

Хидрогеоложки условия в Ботевградската котловина

Groundwater in the Botеvgrad Kettle (West Bulgaria) is important for the local population. Despite the information available for this area, the catchment area of this kettle is poorly studied from a hydrogeological perspective. Therefore, the objective of this current study is to assess the hydrogeological conditions based on existing information for the purpose of better water resource utilization. Using GIS and data from the Geological Map 1:100000 and Hydrogeological Map 1:200000, water types in the Botеvgrad Kettle watershed and their spatial distribution in the area have been determined. The primary focus is on the region's most water-abundant hydrogeological unit, the Quaternary aquifer. Using various GIS layers that characterize spatial changes in hydrogeological characteristics, a conceptual model for this horizon has been developed, facilitating the initiation of activities related to numerical modeling.

FIELD AND MODEL RESEARCH OF THE GROUNDWATER FLOWS IN THE AREA OF THE PAKS-2 NPP CONSTRUCTION, HUNGARY

The construction of the nuclear power plant (NPP) requires conducting a large number of engineering and hydrogeological surveys, as well as assessment of the design decisions’ safety. A deep excavation pit at the Paks II NPP construction site requires execution of the cut-off wall due to extremely high groundwater saturation of the alluvial deposits. However, lithological anisotropy and the presence of dislocation zones did not allow identifying the appropriate depth for the cut-off wall construction. Unfortunately, engineering geological boreholes with a 20-meter distance between them and surface and borehole geophysical surveys could not identify the hydrogeological units. Thus, to conceptualize the hydrogeological settings, an analysis of the groundwater head distribution and the large-scale pumping tests were conducted. The interpretation of the geological data and the distinguishing of the hydrogeological units were carried out iteratively using the hydrogeological numerical model. The flow model could represent the hydraulic head distribution, the response of the lithologically heterogeneous layers to the water fluctuations in the Danube river, and the pumping tests carried out at the different depths. The results of the hydrogeological modeling revealed the aquitard to be continuous throughout the territory; however, its top’s depth changes from 30–35 to 90 m within the construction site of the Paks II NPP. This complex geometry of the aquitard is controlled by the plicated dislocation zone, which cuts the construction site in half and is revealed as the right wall of the graben.Correct hydrogeological stratification enabled us to ensure waterproof activities such as the cut-off wall construction using the hydrogeological model when excavating a deep pit for the Paks II NPP. This also minimizes the hydrodynamic impact on the closely located NPP Paks in operation.

Hydrogeological characterization of the Silala River catchment

AbstractThis article reviews hydrogeological studies carried out between 2016 and 2018 in the Silala River basin, a catchment shared by Chile and Bolivia. These were conducted in the context of the Case Concerning the Status and Use of the Waters of the Silala River, submitted to the International Court of Justice in 2016, and contributed to multidisciplinary science to demonstrate that this system is an international watercourse. In 2016, the hydrogeological understanding of the Silala River basin was poor. The studies reviewed here filled many knowledge gaps, providing a solid hydrogeological baseline, and establishing new monitoring infrastructure to collect relevant aquifer data. The most important hydrogeological units were identified as the fluvial deposits, alluvial deposits, and the Cabana ignimbrite. The latter is highly heterogeneous, weathered and fractured, and exhibits a high permeability. It is the most important unit in terms of productivity, and is the major regional aquifer providing spring flows to Bolivian wetlands and groundwater flow across the international border. The studies provided a preliminary understanding of the main aquifers in Chile and their properties, which underpinned the development of a robust hydrogeological conceptual model of the system, reviewed elsewhere in this special issue. Subsequent refinements are also summarized. This work confirmed that both surface water and groundwater flows from Bolivia to Chile, and thus confirms the status of the Silala River as an international watercourse and provided the basis for a basin‐scale groundwater numerical model, used to investigate the impact of wetland channelization on surface water/groundwater partitioning.This article is categorized under: Science of Water > Hydrological Processes

Qualitative evaluation of groundwater in terms of its suitability for drinking and irrigation. The case study of Sidi-Bel-Abbes alluvial aquifer (NW Algeria)

Sidi-Bel-Abbes province is a semi-arid area mainly used for agricultural activity in northwestern Algeria. Its groundwater resources are characterized by high salinity varying from one area to another. This work aims at improving our understanding of these waters, through hydrochemical classification, to define their chemical facies and monitor their spatial evolution. In addition, this groundwater’s quality is assessed regarding their suitability for drinking and irrigation. The obtained results showed that the groundwater of the Sidi-Bel-Abbes area is dominated by chlorides, particularly the chloride calcium and sodium facies. Indeed, the spatial distribution of the different chemical facies confirmed the contribution of adjacent hydrogeological units and the interaction between the groundwater and the Mekerra Wadi. In terms of suitability for drinking, the maximum chemical element concentration accepted by the Algerian legislation is exceeded in most samples, especially for nitrates, chlorides, sodium and calcium. The interpretation of Riverside and Wilcox diagram revealed that the alluvial groundwater of Sidi-Bel-Abbes is generally characterized by a high salinity with a low to medium alkalinity danger. Therefore, the quality of this water is medium to poor, suitable for irrigation, but under certain conditions. Also, the groundwater is unsuitable for sensitive plants because of its high chloride (Cl) ion content. Moreover, the results obtained indicate that the use of these waters in irrigation presents low sodium risks, and therefore are not likely to modify the structure of the soils in the Sidi-Bel-Abbes plain or reduce their permeability.

Unraveling the impact of dissolved organic matter on arsenic mobilization in alluvial aquifer of the lower Yellow River basin, Northern China

Increased exposure to arsenic (As) has been reported in many arid and semi-arid areas, where drinking water and agricultural irrigation strongly rely on groundwater. High-As groundwater occurred widely in the Northern Henan Plain, which belongs to the lower Yellow River alluvial plain area, posing a new threat to the health of local residents. Based on 77 groundwater samples collected from different hydrogeological units, the sources and optical characteristics of dissolved organic matter (DOM) components in groundwater were analyzed using a three-dimensional fluorescence spectroscopy excitation-emission matrix (3D-EEM) and parallel factor analysis (PARAFAC), to reveal the influence of organic matter on As mobilization and enrichment in Quaternary alluvial aquifers. The results showed that high-As groundwater was concentrated in the areas of the piedmont alluvial depressions and the Yellow River crevasse splay, which was closely related to the richness of organic matter in the buried sediments of the Yellow River paleochannels. Vertically, the variability of groundwater As was governed by the redox conditions and anthropogenic activities, leading to elevated As levels in deep aquifers. High-As groundwater was characterized by high content of humic-like components (C2+C3), strong humification, and weak authigenic sources, which can be attributed to the effects of frequent diversion of the Yellow River and the introduction of more terrestrial humic-like components by intensive agricultural activities (e.g., irrigation). The significant correlations between Fe2+ and As and NH4+ (r = 0.65, 0.48, p < 0.05) as well as the maximum fluorescence intensity of C2 and C3 with As (r = 0.59, 0.74, p < 0.05) reflected the dominant impact of DOM on As migration. The terrestrial-derived high molecular weight organic matter C2 facilitated As mobilization through complexation reactions, while the labile humic-like component C3 triggered the reductive dissolution of iron oxides/hydroxides through microbial metabolic processes, which together contributed to the enrichment of As in groundwater from the Northern Henan Plain.

Geological controls of discharge variability in the Thames Basin, UK from cross-spectral analyses: Observations versus modelling

Geological factors controlling daily- to multi-year discharge variability in 48 sub-catchments spanning 10–1000 km2 in the Thames Basin were investigated using cross-spectral analysis. The analyses represent a ‘transfer function approach’ applied to daily observed streamflow (output) versus catchment-wide precipitation (input) for data spanning 1990–2014. Catchments dominated by high-permeability bedrock have significant attenuation of high-frequency precipitation variability and large delays at all frequencies with streamflow dominated by baseflow (high lag1 autocorrelation and high Base Flow Index, BFI). Catchments dominated by low-permeability rocks have little high-frequency attenuation and small delays and consequently ‘flashy’ behaviour. For all sub-catchments >300 km2 in the Thames Basin, attenuation of the highest frequency precipitation variability caused by mixing of flow from upstream plus groundwater flow (representing ‘older’ variability) with direct surface flow (‘younger’ variability) constitutes real-world moving averaging as indicated by a roll-off in power at the highest frequencies.The success of the JULES land surface model in simulating discharge (i.e. surface and sub-surface runoff routed between grid boxes) is also linked to the underlying geology. Larger catchments (>300 km2) are modelled well because routing between numerous grid boxes leads to moving averaging that is a good analogue for the observations. Modelling was least successful (e.g. lowest Kling-Gupta Efficiency) for small catchments (<300 km2) dominated by high-permeability bedrock - with far too little attenuation of high-frequency precipitation variability and insufficient delays at all frequencies. Experimentally switching the soil saturated hydraulic conductivity to that of the underlying bedrock for grid boxes dominated by aquifers significantly improves modelled discharge variability in small sub-catchments - confirming the importance of bedrock permeability in modelling.For small catchments in data-sparse regions, knowledge of the relative proportions of different hydrogeological units (aquifers, aquitards) potentially could be used to predict and model discharge variability as characterised by BFI and lag1 autocorrelation.

A Hydrogeological Conceptual Model Refines the Behavior of a Mediterranean Coastal Aquifer System: A Key to Sustainable Groundwater Management (Grombalia, NE Tunisia)

The Mediterranean coastal aquifer system of the Grombalia basin (NE Tunisia) offers immense potential as a source of fresh water for agriculture, industry, and drinking water supply. Nonetheless, due to its intricate hydrogeological characteristics and the prevailing issue of groundwater salinity, comprehending its groundwater system behavior becomes crucial for the effective and sustainable management of this aquifer system. Based on the hydrogeological characterization of the Grombalia basin, a novel 3D hydrogeological conceptual model was developed to enhance the understanding of its complex aquifer system. The integration of insights from geological, hydrogeological, hydrodynamic, and hydrochemical components facilitated the construction of the hydrogeological conceptual model. Although the model’s validity faced initial uncertainties due to spatial interpolation of lithological sequences, this study’s thorough and encompassing hydrogeological investigation overcame these limitations. As a result, a more informed comprehension of the aquifer system complexities was achieved. This study reveals that the basin is underlain by an extensive, cohesive Mio–Plio–Quaternary aquifer system. The model demonstrates vertical and lateral hydrogeological continuity between the Quaternary and underlying Mio–Pliocene deposits, enabling groundwater flow and exchange between these layers. Over-abstraction of the Mio–Plio–Quaternary aquifer system has led to a significant drop in piezometric levels and raised the risk of seawater intrusion. These findings emphasize the critical necessity of taking into account the interconnections among hydrogeological units to ensure sustainable groundwater management. The developed conceptual model offers a key tool for understanding the hydrodynamic functioning of the Grombalia aquifer system with a view toward guiding future groundwater management strategies. The application of this approach in the Grombalia basin suggests its potential applicability to other regional aquifers facing comparable challenges.

Typification of coastal depositional lithofacies with isophysical and isochemical hydro-sand beds via stratigraphic modified Lorenz plots (SMLP): geohydrodynamical implications and valorization of hydrogeological units

Typification of coastal depositional lithofacies with isophysical and isochemical hydro-sand beds via stratigraphic modified Lorenz plots (SMLP): geohydrodynamical implications and valorization of hydrogeological units