Groundwater Flow Research Articles

Deciphering inter-catchment groundwater flow: A water balance perspective in the Choshui River Basin, Taiwan

Study regionFive catchments in upstream Choshui River Basin, Taiwan. Study focusInter-catchment groundwater flow (IGF)is commonly assumed negligible role in a catchment water balance due to its obscure nature. Many studies required detailed on-site geological information to analyze and confirm the significance of IGF. In contrast to these studies, this study investigated IGF using the rainfall-runoff model combined with the deterministic optimization algorithm and the stochastic generalized likelihood uncertainty estimation method, relying on simple and easily accessible water balance data. New hydrological insights for the regionThe results showed that the hydrological environment was non-stationary, and IGF inclusion in the model improved its simulation performance. Though IGF direction varied among the catchments, at least three were found with significant IGF potential, with one of the catchments accounting for 30 % (505 mm) of the yearly precipitation. Ignoring IGF may lead to larger errors, especially in smaller catchments and during the dry season. Overall, this study highlights the importance of considering IGF in a catchment water balance and provides insights into the hydrological cycle.

How to consider groundwater flow systems in the Earth's Critical Zone? – Demonstration in the Central Pannonian Basin, Hungary

Study regionCentral Pannonian Basin, Hungary. Study focusCritical Zone (CZ) Science generally focuses on the soil and weathered bedrock in a few or tens of meters depth, thus influence of deeper groundwater on the CZ is understudied. Here we aim to introduce a hydrogeological methodology that can separate normal and abnormal pressure regimes and determine the groundwater flow pattern to characterize the connection of different groundwater flow systems to the CZ. Basin-scale evaluation of about 5500 measured hydraulic data were carried out by p(z) and h(z) profiles, tomographic maps and hydraulic cross sections. New hydrological insights for the RegionThree flow domains were separated and characterized. Namely, i) the uppermost topography-driven flow systems, which penetrate only a few hundred meters, ii) a deep overpressured regime below 1600–2100 m depth, which drives fluids upward; and iii) a newly identified transition zone between the former two, which gains its energy from overpressure dissipation and contains non-renewable water resources. Topography-driven flow systems and discharge areas of the transition zone, where its upwelling saline water contributes to surface salinization, are parts of the CZ. Discharge areas of the transition zone cover about 50% of the Great Hungarian Plain. The overpressured system can only influence the CZ through the transition zone. The approach and methodology can be used in any terrestrial sedimentary basin where a deep overpressured regime exists.

Mechanism controlling groundwater chemistry in the hyper-arid basin with intermittent river flow: insights from long-term observations (2001–2023) in the lower Heihe River, Northwest China

The geochemical processes of groundwater in arid regions are generally influenced by both natural hydrological processes and human activities. However, impacts of water-rock interactions on groundwater recharge via hydrological processes, controlled by both intermittent river water flow and groundwater withdrawals, is still poorly understood. In this study, 327 groundwater chemistry datasets collected from the upper, middle (including Gobi and riparian zones), and lower regions of the Ejina Delta in Northwest China from 2001 to 2023 were analyzed. Our results revealed that the total dissolved solids (TDS) concentration of groundwater in Ejina Delta ranged from approximately 881.5 ± 331.6 mg/L in the upper regions to 1,953.6 ± 1,208.5 mg/L in the lower regions, with an increasing trend observed. Ecological water conveyance (EWC), recharging aquifer through intermittent river water flow, resulted in a decrease in TDS concentrations from 2001 to 2023 mainly in the upper region. While irrigation notably affected groundwater chemistry in the lower region, resulting in a substantial increase in groundwater salinity. Groundwater chemistry in the Middle Gobi region remained relatively stable over the study period. Generally, the hydrochemical composition shifted from the Na-Mg-SO4-HCO3 and Na-Mg-Ca-SO4-HCO3 types in the upper region to Na-Mg-SO4-HCO3 and Na-Mg-SO4-Cl types in the lower region, with Na-SO4-Cl predominant in the Middle Gobi. These shifts were likely be attributed to the interplay of water-rock interactions, coupled with evaporation-crystallization processes. Inverse modeling using PHREEQC revealed that in the upper-middle region, primary water-rock interactions involved calcite dissolution and the precipitation of dolomite, gypsum, halite, and sylvite salts, as well as cation exchange reactions (2NaX+Ca2+→CaX2+2Na+). In contrast, the hydrogeological system in the middle-lower region exhibited an opposite pattern of water-rock interactions. Overall, ecological water conveyance partially facilitated water-rock interactions during lateral groundwater flow, while irrigation disrupted the natural hydrogeochemical equilibrium, involving halite dissolution and opposite cation exchange reactions compared to other regions.

Scaling laws for the modelling of energy geostructures

Among the different solutions to meet the increasing need for renewable energies, energy geostructures, and particularly energy piles, are very promising. However, their dual role (structural support and energy harvester) raises design questions and safety issues. In addition, they are often placed within a groundwater flow and the influence of seepage on thermal loadings and mechanical response is still to be characterised. In this perspective, centrifuge modelling can play a significant role as in lots of geotechnical problems. In the present case, reduced scale models present a supplementary advantage since diffusion timescales are highly reduced. Scaling factor for time is 1/N² if scaling factor for lengths is 1/N. Nevertheless, the numerous phenomena to consider make it difficult to ensure the similarity between model and prototype. The present document derives and gathers all the scaling laws and attention points to keep in mind when centrifuge modelling energy piles.

Illuminating groundwater flow modeling uncertainty through spatial discretization and complexity exploration

Illuminating groundwater flow modeling uncertainty through spatial discretization and complexity exploration

Disclosure of the intricacies in coupled groundwater flow and contaminant transport using mesh-less local Petrov–Galerkin method

Disclosure of the intricacies in coupled groundwater flow and contaminant transport using mesh-less local Petrov–Galerkin method

Groundwater assessment for sustainable development in the Wadi Al-Hamd Basin, Al-Madinah Al-Munawarah, KSA

This study relied on well monitoring many drilled wells data in the Wadi Al-Hamd Basin to determine water level and chemical properties from field measurements. The characteristics of groundwater must be assessed in terms of present and future eases and stresses to ensure sustainable development. Hydrogeological, hydrochemical, groundwater quality indices and Geographic Information Systems (GIS) data sets have been integrated to assess the groundwater aquifer in the study area. To implement this work, we measured the depth to the water table from eighty-eight drilled wells. Also, the major ions were determined from 82 water samples to evaluate the physicochemical properties, groundwater facies, and controlling mechanisms using diagrams such as the modified Piper proposed by Chadha, Total Ionic Salinity (TIS), and Gibbs. In this study, five irrigation water quality indicators (IWQI), including total dissolved solids (TDS), sodium adsorption ratio (SAR), potential salinity (PS), magnesium hazard (MH), and residual sodium carbonate (RSC) have been determined to assess the suitability of groundwater for irrigation. Based on the findings of this study, groundwater flows from the southeast and northwest to the west and south, respectively. In this basin, 56% of water samples have TDS greater than 2000 mg/L, while 62% of water points are categorised as Na–Cl water type, which indicates that evaporation and rock–groundwater interaction influenced groundwater quality evolution. Almost 87% of samples were rated good to excellent for irrigation use with respect to SAR. On the other hand, all water points are suitable for irrigation based on RSC. Likewise, groundwater is suitable for irrigation purposes despite the relatively high PS levels (>5 meq/L in about 49% of samples) and some small spots with high levels of MH (>50% in about 12% of samples), especially in the southern and central portions of the studied basin.

Hydrogeological characterization of low permeability medium for conceptualization of a mine site in Eastern Turkey

The mining site in Eastern Anatolia of Turkey were encounter a significant risk of slope instability within the operational area. One of the processes that govern slope stability is the pore water pressure distribution. The conceptualization and characterization of porous media serve as fundamental prerequisites for the implementation of numerical methods aimed at predicting pore water distribution. This study aims to characterize the hydrogeological properties of water bearing rocks in the active mining site in Eastern Anatolia of Turkey. A total of 21 wells and drill holes were drilled in the study area to conduct in-situ tests, monitoring, and sampling. The large diameter wells drilled in surrounding the carbonate rocks were to determine the groundwater flow and boundary conditions and also wells tapped metasediments and diorite unit for hydraulic testing. The lugeon tests and installation of vibrating wire piezometers were carried out at small diameter drill holes to obtain localized hydraulic conductivity of metasediments and diorite at different depths and monitoring pore water pressure distribution along some critical cross-sections. The results obtained from these tests are used for developing hydrogeological conceptual model for groundwater flow. The results of in-situ tests show that the metasediment and diorite units act as a single hydrostratigraphic unit. The metasediments and diorite have high total porosity and low specific yield indicating that the pore water is retained by electrostatic forces in the medium and it resists flow due to low hydraulic conductivity. The vertical variation in hydraulic conductivity values indicates that the medium is highly heterogeneous.

Structural geology of El Peñón karst system along an anticlinorium of the northern Andes, Colombia

Structural control is one of the most important factors in developing the karstic system since the fractures facilitate the infiltration and circulation of groundwater. This accelerates the mineral dissolution processes responsible for the formation of endo and exokarstic geomorphological features, such as sinkholes and underground cavities, among other landforms that characterize this environment. This study provides information on the structural geology of the El Peñón karstic system, considered one of the most significant and extensive karstic regions in Colombia. The karst is tectonically controlled by joints with a preferential NW-SE orientation and cleavage planes with an NE-SW trend, guiding the development of drainage systems, closed depressions, and underground cavities. The stress tensor obtained with a NW-SE direction (127°) explains the deformation in the area and its influence on the development of the karstic system. It was also established that the potential groundwater flow occurs through open fractures with a direction of 120°–130° (parallel to the stress tensor) and along the cleavage planes (40°–50°). The fracture patterns are characterized by intermediate intensity values, predominantly low fracture density, minimal lengths, and good connectivity between fracture planes.

Numerical approximations of groundwater flow problem using fractional variational iteration method with fractional derivative of singular and nonsingular kernels

This study aims to present the numerical approximations of groundwater flow problem, namely the time-fractional Boussinesq equation using the fractional variational iteration method. Fractional derivatives in time variable are taken in Caputo and Caputo–Fabrizio sense. This work compares the solutions of the time-fractional Boussinesq equation for the Caputo and Caputo–Fabrizio fractional operators. Graphical representation of the water table head’s behavior for different time values is shown.

Using subtle variations in groundwater geochemistry to identify the proximity of individual geological structures: a case study from the Grimsel Test Site (Switzerland)

Understanding groundwater flow and the evolution of groundwater chemistry in networks of fractures in crystalline rock is of fundamental interest for geothermal projects, nuclear waste disposal, and groundwater resources. Groundwater chemistry at a given location is typically conceived of being of a specific ‘type’ (e.g. meteoric, juvenile, connate, marine), with associated chemical types controlled through water-rock interactions. Minor chemical variations between groundwater sample locations with the same chemical type are generally considered as ‘noise’ in the geochemical data. Here, we argue that this noise contains useful information on the mineral phases encountered by the groundwater as it travels through specific flow pathways. We analyse the spatial variability of groundwater chemistry around the Grimsel Test Site (GTS), Switzerland, where groundwater is hosted in two lithologies: the Central Aar Granite and the Grimsel Granodiorite, where flow occurs predominantly in a fracture network created by brittle reactivation of ductile shear zones. Groundwater chemistry is analysed using principal component and hierarchical cluster analyses, which identify two groundwater types based on their chemistry. The primary control on groundwater type is the host rock lithology (granite/granodiorite). While the spatial variability of groundwater chemistry within each of the two lithologies is small, statistical analysis of the data shows similar groundwater chemistry in borehole intervals that are crosscut by similar geological structures, implying a structural control on groundwater chemistry. Our research shows that subtle chemical variations in groundwater provide information on fracture network connectivity and the proximity of geological features, that specific volumes of groundwater has interacted with. Thematic collection: This article is part of the Sustainable geological disposal and containment of radioactive waste collection available at: https://www.lyellcollection.org/topic/collections/radioactive

Evaluating tidal impact on ground source heat exchanger performance under fluctuating groundwater levels

Coastal regions undergo dynamic changes due to tidal forces, posing distinct challenges for groundwater management and utilization of ground source heat pump (GSHP) systems. This study examines the impact of tidal fluctuations on groundwater levels and the performance of ground heat exchangers (GHEs), specifically focusing on the suitability of horizontal directional drilling (HDD) technology in high-tidal zones. Itoman City in Okinawa Prefecture, Southern Japan, serves as an ideal location for this study due to its complex coastal hydrogeological conditions and increasing interest in renewable energy solutions. Employing a comprehensive approach involving field experiments, FEFLOW software simulations, and model validation, we aim to elucidate the intricate relationship between tidal dynamics, groundwater behavior, and GHE performance. Furthermore, our investigation assesses the effectiveness of HDD-GHEs installed in highly tidal-affected zones to determine the optimal installation depth for this type of GHE in coastal regions. According to our research, the layer at a depth of 30 m is most affected by tidal influence and fluctuations in groundwater levels in coastal regions. This layer is the most suitable for installing horizontal HDD-GHEs, with an average heat exchange rate of about 89 W/m. This rate is approximately four and two times higher than the depths above and below this layer, respectively, due to groundwater saturation and flow in the formation. Furthermore, we noticed that the heat exchange rate increases from the top to the bottom of this layer, but the extent of this increase diminishes as the depth increases. This is because deeper depths are less affected by tidal fluctuations in groundwater levels.

Auto‐Pressurized Multi‐Stage Tesla‐Valve Type Microreactors in Carbon Monoliths Obtained Through 3D Printing: Impact of Design on Fluid Dynamics and Catalytic Activity

AbstractThe present research exploits an innovative methodology for producing auto‐pressurized carbon microreactors with a precise and controlled structure analyzing the influence of their design on the fluid dynamics and their catalytic performance. Carbon monoliths with Tesla‐valve shape channels (Tesla, T, and modified Tesla, Tm) are synthesized through the combination of 3D printing and sol–gel process and further probed as Ni/CeO2 supports on CO2 methanation. The experimental results and mathematical modeling corroborated the improved performance obtained through the complex design compared to a conventional one. In addition to chaotic fluid flow induced by the deviation in flow direction, which improves the reagents‐active phase interaction, local pressure increases due to convergence of flows may enhance the Sabatier reaction according to Le Châtelier's principle. Conversely to straight channels, T and Tm are not affected by flow rate and presented chemical control. Tesla‐valve with curved angle (Tm) improved the mass transfer, achieving higher conversion and ≈30% reaction rate increase regarding right angle (T). Thus, this auto‐pressurized multi‐stage Tesla‐valve monolith opens the gate to design specific and advanced functional materials for multitude chemical reactions where not only the reactant‐active phase contact can be maximized but also the reaction conditions can be controlled to maximize the reaction kinetics.

Vulnerability Assessment of Groundwater Influenced Ecosystems in the Northeastern United States

Groundwater-influenced ecosystems (GIEs) are increasingly vulnerable due to groundwater extraction, land-use practices, and climate change. These ecosystems receive groundwater inflow as a portion of their baseflow or water budget, which can maintain water levels, water temperature, and chemistry necessary to sustain the biodiversity that they support. In some systems (e.g., springs, seeps, fens), this connection with groundwater is central to the system’s integrity and persistence. Groundwater management decisions for human use often do not consider the ecological effects of those actions on GIEs. This disparity can be attributed, in part, to a lack of information regarding the physical relationships these systems have with the surrounding landscape and climate, which may influence the environmental conditions and associated biodiversity. We estimate the vulnerability of areas predicted to be highly suitable for the presence of GIEs based on watershed (U.S. Geological Survey Hydrologic Unit Code 12 watersheds: 24–100 km2) and pixel (30 m × 30 m pixels) resolution in the Atlantic Highlands and Mixed Wood Plains EPA Level II Ecoregions in the northeastern United States. We represent vulnerability with variables describing adaptive capacity (topographic wetness index, hydric soil, physiographic diversity), exposure (climatic niche), and sensitivity (aquatic barriers, proportion urbanized or agriculture). Vulnerability scores indicate that ~26% of GIEs were within 30 m of areas with moderate vulnerability. Within these GIEs, climate exposure is an important contributor to vulnerability of 40% of the areas, followed by land use (19%, agriculture or urbanized). There are few areas predicted to be suitable for GIEs that are also predicted to be highly vulnerable, and of those, climate exposure is the most important contributor to their vulnerability. Persistence of GIEs in the northeastern United States may be challenged as changes in the amount and timing of precipitation and increasing air temperatures attributed to climate change affect the groundwater that sustains these systems.

The effects of damming and dam regulation on a river–lake-aquifer system: 3D groundwater flow modeling of Poyang Lake (China)

Large numbers of dams are planned or constructed for hydroelectric power production, water supply, and flood control in many rivers around the world. While the social and environmental impacts of dams are now well-understood, there is little knowledge about the effects of dams on groundwater-surface water interactions in a complex lake–river-aquifer system. This study adopts a three-dimensional groundwater numerical model to quantify the potential impacts of dam construction, on regional groundwater flow system, exemplified by the proposed Poyang Lake Hydraulic Dam (PLHD) in China. Once implemented, the PLHD will regulate lake levels, artificially controlling the lake inundation area during the recession season (September-October) and the dry season (November-December). Modeling results indicated that the increase in lake infiltration induced by PLHD regulation would alter the regional water exchange pattern. The PLHD regulation will likely enhance the groundwater storage by 20.44 % in the general dry year (i.e., 2018), alleviating 78.1 % of the groundwater deficit in the extreme dry year (i.e., 2019). Additionally, the response of groundwater dynamics to the PLHD regulation exhibits significant spatial differences between the upstream and downstream areas of the dam, primarily depending on topographical changes. Overall, the PLHD regulation is most likely to impact groundwater levels across an area of approximately 5,700 km2, and the associated groundwater storage is anticipated to reach a stable state, under future long-term regulation. Our findings may guide policy-makers wishing to develop more suitable PLHD scheduling plans and floodplain protection strategies by providing reliable information regarding groundwater storage change and ecosystem succession.

An Analytic Element Model for Seepage Forces in Fractured Media

AbstractThere are many situations where groundwater flow has high flow rates, causing large seepage forces. Examples are flows around highly conductive fractures and tunnels. We present a new analytic element for a tunnel in an elastic medium. We combined the analytic element method for groundwater flow with that for linear elasticity, and include the seepage force as a body force in the linearly elastic model. We represent tunnels and fractures as analytic elements. The solution for the case considered is limited to steady state flow and fluid-to-solid coupling. We present examples of the computed seepage forces around a tunnel and a fracture as well as a comparison with another numerical model.

Shallow geothermal field multidisciplinary exploration: New data from Campi Flegrei caldera (CFc) for low—middle enthalpy resource exploitation

In the framework of the GeoGrid project, with the specific goal to look for shallow geothermal resources suitable to test the developed technologies, the Agnano geothermal field, a relatively unexplored sector of the eastern Campi Flegrei caldera, was investigated through a multidisciplinary geophysical, stratigraphic and hydro-chemical surveys. Such multidisciplinary approach allows us to reconstruct the subsurface morphology below the Agnano Hyppodrome (AH), interpreted by gravimetric, seismic and stratigraphic data, as a complex structure characterized by a gradual southward and south-eastward deepening of a high-density contrast interface. Moreover, the inferred models show two pronounced lateral depressions in agreement with the existence of known lateral faults bounding the western and eastern flanks of AH, while the hydro-chemical survey of the entire Agnano caldera revealed discontinuous manifestations of thermal waters along the groundwater flow direction. Furthermore, it was found that, within the southern sector of the Agnano caldera, mineralized waters predominantly align with a primary NE-SW buried structural lineament, a feature only hypothesized in previous studies and that in this sector local fresh groundwater likely receives endogenous inputs, including CO2 at elevated temperatures, potentially leading to the mixing of seawater or deep brine. Finally, our results individuate an area north of the Agnano Hippodrome characterized by a significant presence of higher temperature mineralized water, but lacking of seawater enrichment, making it a favorable site for further exploitation of low-to-medium-enthalpy geothermal sources.

Delineation of a conceptual groundwater flow model of the Kandi basin in Benin (West Africa): Insights from isotopes, piezometric and hydrological investigations

Study regionThe hydrogeological Kandi basin, the Benin’s sector of the transboundary Iullumeden basin, located in northern Benin, West Africa Study focusIn many parts of the world, groundwater resources constitute the main, if not the only, source of potable water available to address a growing demand for numerous uses. And yet, a basic understanding of the hydrogeology of many critical groundwater systems is lacking in many instances. Only when severe groundwater depletion or serious groundwater quality issues arise is the attention paid to the lack of specific groundwater studies. This study targets the Kandi basin, a ∼8700 km2 hydrogeological basin located in northern Benin, which is the primary source of potable water for its inhabitants, but its hydrogeological functioning remains unclear. We conducted isotopic and hydrogeological investigations in this basin from 2013 to 2019 to characterize groundwater recharge processes and delineate flow patterns. The resulting hydrological and geochemical data have been integrated and interpreted using tools including mapping tools. New hydrological insights for the regionThis study has identified the preferential groundwater recharge areas and characterized the main groundwater flow paths. Predominant areas of groundwater dischage into surface water, regardless of the seasons, were detected and areas where the surface-groundwater interflows are season-dependent were discriminated. The main findings presented in this paper are expected to provide a baseline for further in-depth hydrogeological investigations, namely groundwater flow modeling that will help understand the impacts of various groundwater withdrawals and climate changes on the groundwater resources availability of this basin.

Hydrogeological assessment and contaminant transport modelling of Enyimba landfill site in Aba, Nigeria

ABSTRACT Commercial and industrial growth in cities generates hazardous waste, often disposed of in open dump sites, contaminating groundwater. Understanding pollutant movement and numerical models are crucial for effective water resource management. This study assessed hydrogeological dynamics and pollutant transfer in the Enyimba landfill site, Nigeria, using field surveys and contaminant modelling to understand groundwater quality and arsenic contamination spread. The research technique included field and laboratory experiments, as well as water sampling during both dry and wet seasons, to evaluate groundwater quality. The geochemical examination of groundwater samples revealed the amounts of several metals using atomic absorption spectrophotometry. The study used contaminant transport modelling with Visual MODFLOW Flex 6.1 and MT3DMS software to simulate groundwater flow and solute transport within the aquifer layers. Predictive simulations over a 20-year timeframe demonstrated the progressive spread of arsenic pollution from the landfill, resulting in an ellipsoid-shaped plume stretching from its source. Arsenic levels have gradually increased, posing a serious threat to groundwater quality and human health. The research highlights the need for remedial measures to reduce groundwater pollution, including waste recovery and recycling facilities and geo-membrane use. It emphasizes proactive actions to protect groundwater supplies and promote environmental sustainability in the Enyimba landfill site.

Relationship among the fault transmissivity, flow dimension, and effective hydraulic conductivity in siliceous mudstone of the Wakkanai Formation around the Horonobe Underground Research Laboratory in Japan

Effective hydraulic conductivity is typically used for evaluating groundwater flow in faulted/fractured media. Estimating effective hydraulic conductivity relies on modelling the transmissivity and hydraulic connectivity of faults/fractures from a large dataset. As an alternative for evaluating hydraulic connectivity, flow dimension is an easily available and quantitative indicator of fault/fracture hydraulic connectivity. However, the flow dimension has not been used quantitatively as much to evaluate the effective hydraulic conductivity. This study demonstrates how flow dimensions in poorly self-sealed faults directly relate to the effective hydraulic conductivities. The effective hydraulic conductivities in massive siliceous mudstone of the Wakkanai Formation around the Horonobe Underground Research Laboratory in Japan were analysed by simulation with long-term (over 10 years) data of hydraulic pressure and inflow during its construction and operation. The estimated effective hydraulic conductivities varied from ≈10 −8 to ≈10 −11 m s -1 with an increasing depth from ≈250 to ≈600 m. The fault local transmissivities and flow dimensions from packer tests varied from ≈10 −6 to ≈10 −10 m 2 s -1 and from ≈2.0 or more to ≈1.0 with increasing depth, respectively. When applying Landau–Lifshitz–Matheron's formula to calculate the fault effective transmissivities, these variations correlate well, and the estimated effective hydraulic conductivities are sound. Thematic collection: This article is part of the Sustainable geological disposal and containment of radioactive waste collection available at: https://www.lyellcollection.org/topic/collections/radioactive