Ground Water[JOURNAL]
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200 papers
Computing Flow-Field Distortion Coefficients from Well-Construction and Formation Properties.
Bayless ER, Ostheimer CJ, Darner RA
Ground Water · 2026 Jul · PMID 42396713 · Publisher ↗
Direct measurements of groundwater velocity made with borehole flowmeters in screened wells must be compensated for the effects of flow-field distortion (also known as borehole acceleration). A theoretical equation devel...
Direct measurements of groundwater velocity made with borehole flowmeters in screened wells must be compensated for the effects of flow-field distortion (also known as borehole acceleration). A theoretical equation developed by Drost et al. (1968) and simple inputs describing hydraulic properties of well construction and geologic formation were programmed into an Excel workbook to facilitate computation by groundwater-flowmeter users. Tables describing the physical and hydraulic properties for well constructions and gravel pack media are provided with an example to facilitate use of the workbook. Groundwater flowlines converge or diverge as they pass from a geologic formation, through a gravel pack and well screen. The extent of flowline convergence or divergence and the value of the flow-field distortion coefficient is related to the relative changes in hydraulic conductivity of the well screen, gravel pack, and geologic formation. Convergence or divergence is accompanied by acceleration or deceleration of groundwater. Direct measurements of groundwater velocity at the center of the monitoring well can be adjusted to provide a more accurate estimate of velocity in the formation by applying a correction for flow-field distortion. Variables required to compute the flow-field distortion coefficient include the hydraulic conductivity of the gravel pack, well screen, and the geologic formation surrounding the well screen; the borehole radius, and the inside radius and outside radius of the well screen.
Leaky Sewers Hydraulically Disconnect from Groundwater: A Proof-of-Concept.
Peche A, Kalwa F, Islam SM … +3 more , Houben G, Graf T, Altfelder S
Ground Water · 2026 Jun · PMID 42227559 · Publisher ↗
Leakage from aging sewer and stormwater pipes into the subsurface poses significant environmental risks and threatens the integrity of urban infrastructure, primarily through the degradation of groundwater quality and th...
Leakage from aging sewer and stormwater pipes into the subsurface poses significant environmental risks and threatens the integrity of urban infrastructure, primarily through the degradation of groundwater quality and the alteration of urban water balances. While the presence of defects within pipe networks is well-documented, accurately quantifying volumetric exchange fluxes remains a challenge due to the complex, nonlinear interactions between the pipe, the surrounding variably saturated soil, and the fluctuating groundwater level. Current modeling approaches often overlook the threshold behaviors of these systems, leading to potential inaccuracies in leakage estimation. In this study, we show for the first time that leaky pipes can become hydraulically disconnected from the underlying groundwater, a phenomenon analogous to well-known river-groundwater interactions that include disconnection. In a sewer-groundwater context, hydraulic disconnection is restricted to point sources and is strongly influenced by colmation/clogging. Through numerical modeling of a hypothetical case study, we show that the leakage flux from the pipe (in absolute terms) initially increases with declining groundwater levels, until a critical depth below the leaky pipe is reached. After this point, the hydraulic communication from the groundwater to the leaky pipe stops and the leakage flux can be considered constant. In a sensitivity analysis, we demonstrate the impact of the individual hydraulic parameters of the leaky-pipe-groundwater system on the hydraulic disconnection. We further modify the properties of the aquifer material, resulting in a hydraulic disconnection depth of 0.89 m, 1.77 m and 4.00 m below pipe for sand, loamy sand and sandy loam aquifers, respectively. This insight has important implications for leakage modeling: once hydraulic disconnection occurs, the leakage flux becomes independent of groundwater dynamics. The present study provides a proof-of-concept for the mechanism by which leaky sewers hydraulically disconnect from groundwater.
Python-Based Model Emulation Workflows with PEST.
Hugman R, White J
Ground Water · 2026 May · PMID 42207131 · Publisher ↗
Computational demands for uncertainty quantification and optimization often exceed available resources for high-fidelity environmental models. While surrogate modeling (or model emulation) offers a pragmatic solution, wi...
Computational demands for uncertainty quantification and optimization often exceed available resources for high-fidelity environmental models. While surrogate modeling (or model emulation) offers a pragmatic solution, widespread adoption is hindered by a significant "implementation gap": practitioners often lack standardized, robust tools to integrate emulation techniques directly into existing modeling workflows, relying instead on bespoke implementations. To bridge this gap, we present the Emulator module within the open-source pyEMU package. This framework provides a "plug-and-play" architecture for deploying Gaussian Process Regression (GPR), Data-Space Inversion (DSI) and other model emulation approaches. The framework automates the complex "plumbing" of emulation-based workflows, including non-Gaussian data transformation and the generation of PEST interface files, allowing trained surrogates to serve as drop-in replacements for physics-based models. We believe this one-to-one correspondence between physics-based model and emulator-based workflows will facilitate direct comparisons between the two so that the community in general can build up the knowledge of when and how to effectively and appropriately deploy emulation. We demonstrate the utility of these tools through a benchmarking optimization problem and a history-matching application on a synthetic groundwater model.
Hydrogeology in the Age of AI and Climate Change.
Latif SD
Ground Water · 2026 May · PMID 42204849 · Publisher ↗
Abstract loading — click title to view on PubMed.
Aquifer Thermal Energy Storage: Groundwater for Efficient Data Center Cooling in the United States.
Pandey U, Stumpf AJ, Lin YF
Ground Water · 2026 May · PMID 42186915 · Publisher ↗
Data centers are energy end users with the fastest growing need for electricity in the United States, mainly because of the rapid expansion of cloud computing and artificial intelligence (AI). A substantial portion of th...
Data centers are energy end users with the fastest growing need for electricity in the United States, mainly because of the rapid expansion of cloud computing and artificial intelligence (AI). A substantial portion of this electricity, between 10% and 40%, is used for cooling. As the number of data centers increases and the sector's energy demand continues to rise exponentially, there is an urgent need to explore the use of alternative energy systems that are more efficient and sustainable. This article explores aquifer thermal energy storage (ATES) as a technically feasible and currently underutilized solution for data center cooling in the United States. Previous case studies from Europe and assessments based in the United States are considered, and the potential of ATES for reducing electricity usage for data centers, which would reduce overall greenhouse gas emissions and support sustainable energy operations.
Simulating the Impacts of Deep Geothermal Development on Shallow Hydrothermal Resources in a Rocky Mountain Rift Valley.
Rush MJ, Birdsell D, Foster L … +3 more , Reichenbacher R, Rehmus P, Armstrong T
Ground Water · 2026 May · PMID 42149562 · Publisher ↗
Numerical modeling has been widely used to assess the feasibility of geothermal energy development at sites across the world, but modeling applications simulating the potential impacts on shallow hydrothermal resources a...
Numerical modeling has been widely used to assess the feasibility of geothermal energy development at sites across the world, but modeling applications simulating the potential impacts on shallow hydrothermal resources and surface water are relatively scarce. In this study, we apply the MODFLOW 6 groundwater energy (GWE) code to simulate fully coupled groundwater flow and heat transport in a Rocky Mountain rift valley. The site features a moderate temperature hydrothermal system with steeply dipping normal faults, fractures, and shear zones that convey upwelling geothermal water to the shallow subsurface and facilitate interaction between deep geothermal pumping and the shallow subsurface. Following calibration against a set of publicly available well water levels, streamflow observations, well and spring water temperatures, and thermal gradients, the model is used to simulate the impacts of deep geothermal development on surface water supplies and shallow hydrothermal resources, including a hot spring system. The model simulates significant hydrologic and thermal impacts of deep geothermal pumping on the shallow hydrothermal system, including large changes in groundwater levels (-1.2 to +3.1 m), temperatures (-5.6°C to +8.7°C), and groundwater flow to springs (-10.7% to +15.4%). Depletion of tributary groundwater is simulated in three scenarios (0.8-10.7% of the geothermal extraction rate), demonstrating that deep geothermal pumping can infringe upon surface water rights. Results broadly demonstrate that in rift valley systems, geologic structures conveying upwelling geothermal water can lead to surficial thermal and hydrologic impacts in response to deep geothermal pumping, highlighting the need for regulatory frameworks that integrate geothermal energy and water resources.
Discharge-Targeted Hydraulic Tomography to Quantify and Locate Aquifer Discharge.
Drach K, Leven C, Cirpka OA
Ground Water · 2026 May · PMID 42139043 · Publisher ↗
Quantifying and localizing groundwater discharge is inherently difficult. It requires knowledge about hydraulic conductivity and the hydraulic gradient on the scale of interest. Conventional hydraulic testing, such as pu...
Quantifying and localizing groundwater discharge is inherently difficult. It requires knowledge about hydraulic conductivity and the hydraulic gradient on the scale of interest. Conventional hydraulic testing, such as pumping tests, may fail in the presence of heterogeneity and complex structural boundaries. While advanced 2D and 3D hydraulic tomography may resolve small-scale heterogeneity, it is typically limited to small spatial scales and requires costly field installations. We propose a simplified tomographic approach using a limited number of pumping and observation wells spatially distributed over a well profile in the order of 100 m transverse to the direction of ambient flow. To infer the spatially variable hydraulic-conductivity field from drawdown data with its uncertainty, we apply an iterative ensemble smoother. Subsequently, the posterior ensemble of hydraulic-conductivity fields is used to calculate total and specific discharge based on the observed ambient hydraulic heads in the same wells. We test our approach in a synthetic scenario mimicking a channel-like aquifer such as the quaternary fill in a small river valley. The results demonstrate that multiple spatially distributed pumping tests are suitable to quantify total discharge and its associated uncertainty. The approach is more reliable than a conventional one that estimates effective transmissivity from fitting analytical solutions to pumping-test data. The tomographic analysis additionally allows locating spatial patterns of specific discharge at a resolution similar to the spacing of the wells, which may be important when assessing and remediating contaminant plumes.
Enhancing Recharge in the Edwards Aquifer, Texas: Measures, Outcomes, and Lessons for Karst Aquifers.
Thapa Magar N, Mace RE
Ground Water · 2026 May · PMID 42132308 · Publisher ↗
Managed aquifer recharge is a widely adopted method that involves storing excess water underground for future use. While managed aquifer recharge has been applied globally to different aquifer types, its use in karst aqu...
Managed aquifer recharge is a widely adopted method that involves storing excess water underground for future use. While managed aquifer recharge has been applied globally to different aquifer types, its use in karst aquifers is less common due to the unique hydrogeological characteristics of these systems, including high permeability, variable water flow velocities, and shorter water residence times. Consequently, there is a gap in studies assessing managed aquifer recharge effectiveness in karst aquifers. The Edwards Aquifer in south-central Texas, which provides water to over 2 million people, is an example where recharge enhancement strategies have been explored. This study synthesizes enhanced recharge measures in the Edwards Aquifer from the 1960s to 2024, assessing their benefits, limitations, and regulatory frameworks guiding these strategies. By reviewing state water codes, rules, articles, technical reports, and case studies, this study reveals purpose and methods of recharge enhancement in the region. Findings suggest that while recharge dams, designed for flood control, have contributed to enhancing recharge, their impact remains marginal compared to natural recharge volumes. Aquifer storage and recovery emerged as a key strategy to store Edwards water in other stable aquifers and the brackish zone of the Edwards Aquifer. Recirculation and springflow augmentation were explored but not implemented due to uncertainties. Other initiatives focused on enhancing the quality of water entering the aquifer. Enhanced recharge in karst aquifers (or using karst aquifers' water to enhance recharge in other aquifers) is important as societies continue to face challenges due to population growth and environmental changes.
Considerations for the Design of Sinusoidal Slug Testing Methods.
Turnadge C, Burk L, Banks EW
Ground Water · 2026 May · PMID 42095376 · Publisher ↗
Modern methods of aquifer hydraulic testing estimate subsurface properties by creating frequency-dependent variations in groundwater well levels. These methods are variously known as periodic, harmonic, or oscillatory hy...
Modern methods of aquifer hydraulic testing estimate subsurface properties by creating frequency-dependent variations in groundwater well levels. These methods are variously known as periodic, harmonic, or oscillatory hydraulic testing, of which sinusoidal testing is a specific case. Periodic testing provides several potential advantages over traditional methods, including larger signal-to-noise ratios, larger distances over which hydraulic disturbances propagate, and the ability to undertake zero net water extraction. One of three approaches are used to induce groundwater pressure fluctuations: (1) extraction/reinjection of water using motorized pumps, (2) pressurization/depressurization using compressed air, and (3) transient displacement of the water column by slug testing. The latter was the focus of the present study; specifically, how to improve sinusoidal slug testing methods by ensuring accurate generation of sinusoidal variations in well water levels. Two previously published sinusoidal testing designs were evaluated in terms of the ratio of effective transfer link length, , to effective flywheel radius, . The first published design featured ratio values ranging from 13 to 9, which corresponded to maximum discrepancies between intended and actual slug movement of 7% to 10%, respectively. The second design featured ratio values ranging from 12 to 2, which corresponded to maximum discrepancies of 8% to 29%, respectively. These analyses suggest that methods featuring a rotating drive coupled to an effective transfer link are suboptimal. Instead, designs featuring either modified flywheel apparatus or winches driven by digitally controlled stepper motors can minimize the potential for discrepancies between intended and actual slug movement. The accurate generation of sinusoidal slug movement will minimize uncertainties associated with hydraulic properties inversely estimated from observations acquired during sinusoidal slug testing.
When Density Matters: Hydraulic and Salinity Evolution in Groundwater-Fed Pit Lakes in Semiarid and Arid Climates.
Moser B, Cook PG, Greskowiak J … +1 more , Wallis I
Ground Water · 2026 May · PMID 42093331 · Publisher ↗
Although groundwater flow directions are influenced by hydraulic gradients and density gradients, density gradients are often assumed negligible outside coastal zones and saline lake environments. Density gradients are r...
Although groundwater flow directions are influenced by hydraulic gradients and density gradients, density gradients are often assumed negligible outside coastal zones and saline lake environments. Density gradients are rarely considered in mining studies, but can alter groundwater flow patterns, and cause outflow of water from pit lakes despite inward hydraulic gradients. Open mine pits often intersect regional water tables, requiring dewatering during mining operations. At the end of mine life, groundwater abstraction ceases, frequently leading to the development of pit lakes. Due to prolonged water residence time, and evaporation, pit lake water quality may deteriorate with salinization being a common problem. While salinity differences between pit lake water and groundwater are small initially, they increase with time, inducing density contrasts. Consequently, dense pit lake water may move along density gradient towards less dense groundwater. This changes the flow patterns around the pit lake and impact on surrounding aquifer water quality. In this study, we advance process understanding of how density effects alter flow and salinity patterns in pit lake environments post-mining using numerical modeling. We show the impact of ambient groundwater salinity, regional hydraulic gradients, evaporation rates, and hydraulic conductivities on the interaction between a pit lake and the surrounding aquifer. We demonstrate how density effects can substantially increase lake water outflow and decrease pit lake water salinities. Pit lakes can turn from terminal sinks into throughflow systems purely due to variable-density flow. Understanding the hydraulic and salinity evolution of pit lakes is crucial for planning post mining rehabilitation.
Impacts of Different Boundary Conditions on Dirac Pulse from a Well into Aquifer.
Li G, Shen X, Liu Z
Ground Water · 2026 May · PMID 42085071 · Publisher ↗
For a partially penetrating well, a Dirac pulse can be generated by sudden charge of water from the well end into the contiguous rock, and subsequently the pulse diffuses away in terms of slow P-wave. This process is des...
For a partially penetrating well, a Dirac pulse can be generated by sudden charge of water from the well end into the contiguous rock, and subsequently the pulse diffuses away in terms of slow P-wave. This process is described by the Green's function for the initial-value problem. The Green's functions subject to three boundary conditions (BC) are compared mutually, that is, no BC, zero Neumann BC and zero Dirichlet BC for infinitely far boundary, the confining unit and unconfined aquifer, respectively. The well end is set at 10 m below the boundary, and the mass of water suddenly injected is prescribed as 1 kg. Both intact Berea sandstone and fractured Berea sandstone are used for illustration. The spatial distribution and breakthrough curve of the fluid pressure disturbance (p) are calculated. The results indicate that zero Neumann BC increases p whereas zero Dirichlet BC decreases p. For slow and fast P-waves in the regime of low frequency, it is rigorously shown that the ratios (between the confining pressure disturbance and fluid pressure disturbance) are lower than and higher than unity, respectively. This theoretical study suggests that the technique of Dirac pulse may be used for acquisition of small-scale permeability, thus helpful for resolving the heterogeneity of in situ permeability.
A New Era of Collaborative MODFLOW Development.
Fienen MN, Hughes JD, Langevin CD … +4 more , Morway ED, Panday S, Provost AM, Russcher MJ
Ground Water · 2026 · PMID 42059836 · Publisher ↗
Abstract loading — click title to view on PubMed.
Imaging Point Source Groundwater Discharges in a Confined Coastal Aquifer Using Electrical Resistivity.
Gómez-Nicolás M, Huitzilt-Rodriguez A, Iñiguez E … +4 more , Pacheco-Castro R, Pérez-Flores M, Salles P, Whitaker F
Ground Water · 2026 Apr · PMID 42043468 · Publisher ↗
Point-source submarine groundwater discharge (PSGD) delivers mass and solutes and locally reduces salinity along karstic coasts, yet the geometry of conduits conveying meteoric and mixed waters is rarely imaged. Here we...
Point-source submarine groundwater discharge (PSGD) delivers mass and solutes and locally reduces salinity along karstic coasts, yet the geometry of conduits conveying meteoric and mixed waters is rarely imaged. Here we present the first marine electrical resistivity tomography (ERT) characterization of PSGD along the northwestern Yucatán Peninsula and evaluate marine ERT across contrasting settings to detect and characterize PSGD conduits and the confining coastal aquitard under field conditions. Four dipole-dipole ERT profiles span an intact coastal aquitard on land (Sisal), a coastal lagoon perforated by PSGD (Dzul-Ha), and their offshore equivalents near the Xbuya-Ha vent. On land, a laterally continuous resistive horizon at -5 to -9 masl overlies low-resistivity units that host saline groundwater and is interpreted as a cemented coastal aquitard that confines the aquifer. Beneath Dzul-Ha, the inversion images an elongated conductive chimney that cross-cuts this horizon and coincides with the mapped PSGD. Seabed profiles near Xbuya-Ha resolve discrete resistive bodies embedded in a conductive matrix at the main and secondary PSGDs. Forward modeling shows that conduits remain detectable even when the salinity contrast generated by freshwater discharge is weak; however, anomaly amplitudes decrease with increasing sea-floor depth, following an exponential decay with a characteristic depth of ~8 m. Together, these results provide a resistivity-based framework for combining tracers and flow models to quantify PSGD fluxes. Because the study targets vigorous PSGD under favorable electrical contrasts, these performance estimates represent an upper bound and clarify the limits of marine ERT for detecting PSGD in comparable karstic coasts.
Predicting Groundwater Hydrochemical Facies in Three Dimensions with Random Forest Classification, USA.
Stackelberg PE, Knierim KJ, Belitz K … +3 more , Cravotta CA, McCleskey RB, Killian CD
Ground Water · 2026 Apr · PMID 42029972 · Publisher ↗
A random forest classification (RFC) model was developed to predict hydrochemical facies (HCFs) of groundwater in three dimensions across the conterminous United States (CONUS). Major-ion data from 152,673 sites were use...
A random forest classification (RFC) model was developed to predict hydrochemical facies (HCFs) of groundwater in three dimensions across the conterminous United States (CONUS). Major-ion data from 152,673 sites were used to categorize groundwater into one of six HCFs (CaMg-HCO, NaK-HCO, CaMg-SO, NaK-SO, Cl, or Mixed). These six HCFs were used as targets for RFC modeling. Model features that represent relevant geochemical processes and/or physical conditions were derived from previously published data. Additional model features were specifically engineered to support this analysis: elevation of the bottom of a well relative to the base of drinking water (ERDW) and six flags that relate geologic units to HCFs. The most important model feature was ERDW. The model was used to map HCFs at a 1-km resolution across CONUS and to depths of 400 m below the base of drinking water (which varies from 22 m to 2 km). Model predictions are consistent with expectations. CaMg-HCO is predicted to occur near the water table in more humid settings, and areas underlain by carbonate or crystalline rocks. At depths below the base of drinking-water supplies, the model predicts a rapid transition from HCO HCFs to Cl. Model predictions are accurate based on point data, and data averaged across hydrogeologic regions and with depth. Model predictions of HCFs could be used for multiple purposes, including the mapping of salinity and other groundwater characteristics.
Opportunistic Recharge Enhancement in Arid and Semi-Arid Regions.
Gupta N, Lima R, Sankey TT … +11 more , Mroczek C, Jacobs K, Lewis R, Bromley F, Xu T, Richter H, Broxton P, Korgaonkar Y, Zalesky T, Famiglietti J, Springer A
Ground Water · 2026 · PMID 41979980 · Full text
Groundwater supplies are stressed by climatic trends, increasing withdrawals, and multiple competing uses, especially in arid and semi-arid environments. We propose opportunistic recharge enhancement (ORE) as a cross-dis...
Groundwater supplies are stressed by climatic trends, increasing withdrawals, and multiple competing uses, especially in arid and semi-arid environments. We propose opportunistic recharge enhancement (ORE) as a cross-disciplinary, scalable framework to augment groundwater supplies by strategically integrating recharge co-benefits into existing land and water management practices such as forest thinning and stormwater management. These opportunities would allow for enhanced recharge across diverse landscapes, potentially increasing water availability for both human uses and natural systems. A key incentive for ORE is that, while there may be some increases in cost in some cases, the benefits and opportunities for funding may be significantly expanded. Using Arizona, USA, a region experiencing acute groundwater stresses, as an example, we illustrate how ORE can offer a complementary pathway to groundwater resilience with potential to extend to semi-arid and arid areas globally.
Natural Language Processing for Groundwater Insights.
Christenson C, McCoy K
Ground Water · 2026 Apr · PMID 41949484 · Publisher ↗
Abstract loading — click title to view on PubMed.
Layered Radial Aquifer Model for Open-Pit Mine Closure with Managed Aquifer Recharge.
Ataie Ashtiani B
Ground Water · 2026 Apr · PMID 41949473 · Publisher ↗
Open-pit mine dewatering can delay post-closure pit-lake recovery and is increasingly managed using managed aquifer recharge (MAR). We develop a radially symmetric two-aquifer model that couples an unconfined aquifer, a...
Open-pit mine dewatering can delay post-closure pit-lake recovery and is increasingly managed using managed aquifer recharge (MAR). We develop a radially symmetric two-aquifer model that couples an unconfined aquifer, a leaky aquitard, and an underlying confined aquifer to a pit water-balance equation, extending Cook et al. (2022) to layered systems. MAR is represented by reinjecting prescribed fractions of the time-varying pumping rate at a ring radius r, with flexible allocation between unconfined and confined injection. Nondimensionalization yields transferable type curves and a design workflow controlled by K/S, Kc/Sc, Λ/S, r/r, and the far-field head ratio α. We evaluate 15 hydrogeologic scenarios (H0-H14) under three MAR allocations (no MAR, MAR, MAR). Across scenarios, reinjecting 80% of pumped water to the unconfined aquifer (MAR) reduces the time for the pit water level to return within 5 m of the pre-mining unconfined head from 21-48 year (no MAR) to 1.8-28 year, with a median recovery-time ratio of 0.17, while increasing mean pumping by a median factor of 1.31. Splitting the same reinjection fraction between unconfined and confined aquifers can further shorten recovery when vertical coupling is moderate to high (Λ/S ≳1), but increases mounding and recycling. Layering matters: for the same MAR policy, the layered base case predicts recovery times a factor of ~2-3 shorter than the homogeneous limit. The results provide screening guidance on when confined-aquifer injection can accelerate recovery without unacceptable unconfined mounding.
Deep Groundwater Total Dissolved Solids Mapping in the Dakota Group, Williston Basin, USA.
Stephens MJ, Hoogenboom BE, Ball LB … +1 more , Chang W
Ground Water · 2026 · PMID 41931302 · Full text
Growing concern about the quantity of available freshwater around the world has led to interest in surveying groundwater total dissolved solids (TDS) below water well depths. Deep TDS has not been systematically mapped,...
Growing concern about the quantity of available freshwater around the world has led to interest in surveying groundwater total dissolved solids (TDS) below water well depths. Deep TDS has not been systematically mapped, and there is much to learn about the distribution and controls on deeper groundwater. In sedimentary basins across the United States, groundwater resources often overlie hydrocarbon resources, providing an opportunity to use borehole geophysical data collected for hydrocarbons to characterize groundwater and pore space resources. This study adapts a recently developed subsurface geostatistical and geophysical modeling approach to continuously map groundwater TDS, porosity, and temperature in the Dakota Group of the Williston Basin-an undercharacterized regional aquifer system overlying deeper hydrocarbon reservoirs. Groundwater TDS in the Dakota Group ranges from approximately 4800 to 26,900 mg/L. TDS patterns are stratified with higher TDS in the lower and upper Dakota Group, and relatively lower TDS in the middle Dakota Group. The lower TDS in the middle zone may represent a preferential regional flow path for lower-TDS meteoric recharge from the west. The alternating pattern of TDS may also be evidence of higher-TDS inflows into the Dakota Group from underlying and potentially from overlying aquifers. Porosity is lower near the center of the Williston Basin and tends to be higher to the east, which may be related to grain size distributions. The new regional TDS and porosity modeling serves as a quantitative reference for water users and provides supporting evidence for hypotheses on Dakota Group recharge.
Bronze Age Sacred Wells of Sardinia, Italy: Groundwater Access Without Water Utility.
Jiao JJ
Ground Water · 2026 · PMID 41926157 · Publisher ↗
In Late Bronze Age Sardinia, Italy (ca. 1350-1200 BC), communities constructed distinctive stone structures centered on vertical shafts intersecting the groundwater table or monumentalized natural springs. Conventionally...
In Late Bronze Age Sardinia, Italy (ca. 1350-1200 BC), communities constructed distinctive stone structures centered on vertical shafts intersecting the groundwater table or monumentalized natural springs. Conventionally termed pozzi sacri ("sacred wells") or "well temples" in archeological literature, approximately 66 sites containing 75 monuments have been documented. Included on Italy's Tentative List for UNESCO World Heritage nomination, these monuments have attracted considerable public interest and continue to draw visitors from around the world. These structures feature elaborate masonry, descending staircases, and ritual deposits, yet their design appears poorly optimized for water collection which is significantly different from sacred wells elsewhere in the world. This note examines the physical dimensions of these monuments, highlighting that although excavation depths vary, with some extending significantly below the water table, chambers were designed to accommodate shallow water accumulation rather than deep storage. Using Santa Cristina, Cuccuru Nuraxi, and Su Tempiesu-Orune as case studies, the analysis demonstrates that paved chamber floors and design choices distinguishing these structures from utilitarian wells are consistent across the inventory. While the term "well" implies water extraction, the archeological evidence suggests groundwater may have been conceptualized as a subterranean boundary rather than a primary resource target.
Hydroclimatic Drivers of Groundwater Resilience in Cold Humid Regions.
Blin N, Soonthornrangsan J, Lowry C … +3 more , Gironás J, Chadwick C, Suárez F
Ground Water · 2026 · PMID 41910184 · Publisher ↗
Effective water resource management, particularly in assessing the impacts of climate change on water-abundant regions, is crucial for ensuring long-term sustainability. This study investigates the hydrological response...
Effective water resource management, particularly in assessing the impacts of climate change on water-abundant regions, is crucial for ensuring long-term sustainability. This study investigates the hydrological response of a cold humid basin with strong groundwater-surface water interactions located in the Great Lakes Basin. We employ a coupled groundwater-surface water model (GSFLOW) to simulate the complex hydrological processes and evaluate the potential buffering capacity of groundwater on surface water systems. Results reveal a strong linear relationship between changes in mean annual precipitation and groundwater recharge (R = 0.96), with annual precipitation increases over 165 mm required to generate positive changes in recharge. The groundwater system demonstrates significant buffering capacity, particularly in areas with shallow water tables and during hydrological recession periods. Key buffering mechanisms include lagged responses to projected changes in precipitation and recharge relative to the reference period, shifts toward winter recharge, and stable baseflow during dry periods. The aquifer shows greater resilience under the more extreme SSP5 8.5 scenario, suggesting more dynamic surface-groundwater interactions under intense climate conditions. Spatial analysis indicates higher sensitivity to precipitation changes in areas with deeper water tables. The shifts in recharge timing suggest a transition from snow-dominated to rain-dominated winter hydrology, potentially enhancing the system's buffering capacity. These findings provide crucial insights for water resource management in cold humid regions, emphasizing the importance of considering a range of climate scenarios in long-term planning and highlighting the critical role of groundwater in maintaining hydrological resilience under changing climate conditions.
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