Ground Water[JOURNAL]
Sun
200 papers
Continental Scale Hydrostratigraphy: Basin-Scale Testing of Alternative Data-Driven Approaches.
Tijerina-Kreuzer D, Swilley JS, Tran HV … +5 more , Zhang J, West B, Yang C, Condon LE, Maxwell RM
Ground Water · 2024 · PMID 37768270 · Publisher ↗
Integrated hydrological modeling is an effective method for understanding interactions between parts of the hydrologic cycle, quantifying water resources, and furthering knowledge of hydrologic processes. However, these...
Integrated hydrological modeling is an effective method for understanding interactions between parts of the hydrologic cycle, quantifying water resources, and furthering knowledge of hydrologic processes. However, these models are dependent on robust and accurate datasets that physically represent spatial characteristics as model inputs. This study evaluates multiple data-driven approaches for estimating hydraulic conductivity and subsurface properties at the continental-scale, constructed from existing subsurface dataset components. Each subsurface configuration represents upper (unconfined) hydrogeology, lower (confined) hydrogeology, and the presence of a vertical flow barrier. Configurations are tested in two large-scale U.S. watersheds using an integrated model. Model results are compared to observed streamflow and steady state water table depth (WTD). We provide model results for a range of configurations and show that both WTD and surface water partitioning are important indicators of performance. We also show that geology data source, total subsurface depth, anisotropy, and inclusion of a vertical flow barrier are the most important considerations for subsurface configurations. While a range of configurations proved viable, we provide a recommended Selected National Configuration 1 km resolution subsurface dataset for use in distributed large-and continental-scale hydrologic modeling.
From the Mental to the Conceptual Model: The Challenge of Teaching Hydrogeology in the Field.
Jimenez-Martinez J
Ground Water · 2023 · PMID 37747102 · Publisher ↗
Field-based learning in hydrogeology enables students to develop their understanding and application of practical methodologies, and to enhance many of the generic skills (e.g., teamwork, problem-solving). However, teach...
Field-based learning in hydrogeology enables students to develop their understanding and application of practical methodologies, and to enhance many of the generic skills (e.g., teamwork, problem-solving). However, teaching and learning hydrogeology in general, and especially in the field, presents cognitive difficulties, such as the diversity in student education and experience, the hidden nature of water movement and transport of chemicals, and the preexisting students' mental models of the subsurface, in particular. At any given experimental or teaching site there is only one reality for which lecturers can have an approximate conceptual model, including aquifer(s) geometry and functioning (e.g., flow direction). However, students' preconceptions (i.e., mental model), in some cases misconceptions, influence not only their outcome from the learning strategy designed, but also the conceptual model expression (i.e., flow chart, block diagram, or similar) for the study area or site. In practice, two general "teaching challenges" are identified to enable students' transition from the mental to the conceptual model: (1) identify and dispel any prior misconceptions and (2) show how to go from the partial information to the integration of new information for the development of the conceptual model. The inclusion of specific prior-to-field lessons in the classroom is recommended and in general, done. However, introducing a prior-to-field survey to learn about students' backgrounds, and methodologies for the development and expression of hydrogeological conceptual models and for testing multiple plausible conceptual models will help students transition from the mental to the conceptual model.
Continental Scale Hydrostratigraphy: Comparing Geologically Informed Data Products to Analytical Solutions.
Swilley JS, Tijerina-Kreuzer D, Tran HV … +4 more , Zhang J, Yang C, Condon LE, Maxwell RM
Ground Water · 2024 · PMID 37714744 · Publisher ↗
This study synthesizes two different methods for estimating hydraulic conductivity (K) at large scales. We derive analytical approaches that estimate K and apply them to the contiguous United States. We then compare thes...
This study synthesizes two different methods for estimating hydraulic conductivity (K) at large scales. We derive analytical approaches that estimate K and apply them to the contiguous United States. We then compare these analytical approaches to three-dimensional, national gridded K data products and three transmissivity (T) data products developed from publicly available sources. We evaluate these data products using multiple approaches: comparing their statistics qualitatively and quantitatively and with hydrologic model simulations. Some of these datasets were used as inputs for an integrated hydrologic model of the Upper Colorado River Basin and the comparison of the results with observations was used to further evaluate the K data products. Simulated average daily streamflow was compared to daily flow data from 10 USGS stream gages in the domain, and annually averaged simulated groundwater depths are compared to observations from nearly 2000 monitoring wells. We find streamflow predictions from analytically informed simulations to be similar in relative bias and Spearman's rho to the geologically informed simulations. R-squared values for groundwater depth predictions are close between the best performing analytically and geologically informed simulations at 0.68 and 0.70 respectively, with RMSE values under 10 m. We also show that the analytical approach derived by this study produces estimates of K that are similar in spatial distribution, standard deviation, mean value, and modeling performance to geologically-informed estimates. The results of this work are used to inform a follow-on study that tests additional data-driven approaches in multiple basins within the contiguous United States.
Coastal Groundwater-Dependent Ecosystems are Falling Through Policy Gaps.
Dyring M, Rohde MM, Froend R … +1 more , Hofmann H
Ground Water · 2024 · PMID 37697806 · Publisher ↗
Coastal groundwater-dependent ecosystems (GDEs), such as wetlands, estuaries and nearshore marine habitats, are biodiversity hotspots that provide valuable ecosystem services to society. However, coastal groundwater and...
Coastal groundwater-dependent ecosystems (GDEs), such as wetlands, estuaries and nearshore marine habitats, are biodiversity hotspots that provide valuable ecosystem services to society. However, coastal groundwater and associated ecosystems are under threat from groundwater exploitation and depletion, as well as climate change impacts from sea-level rise and extreme flood and drought events. Despite many well-intentioned policies focused on sustainable groundwater use and species protection, coastal GDEs are falling through gaps generated by siloed policies and as a result, are declining in extent and ecological function. This study summarized then examined policies related to the management of coastal groundwater and connected ecosystems in two key case study areas: Queensland (Australia) and California (USA). Despite both areas being regarded as having progressive groundwater policy, our analysis revealed three universal policy gaps, including (1) a lack of recognition of the underlying groundwater system, (2) fragmented policies and complex governance structures that limit coordination, and (3) inadequate guidance for coastal GDE management. Overall, our analysis revealed that coastal GDE conservation relied heavily on inclusion within protected areas or was motivated by species recovery, meaning supporting groundwater systems remained underprotected and outside the remit of conservation efforts. To close these gaps, we consider the adoption of ecosystem-based management principles to foster integrated governance between disparate agencies and consider management tools that bridge traditional conservation realms. Our findings advocate for comprehensive policy frameworks that holistically address the complexities of coastal GDEs across the land-sea continuum to foster their long-term sustainability and conservation.
Resolving the Water Crisis: There's a Way, But Is There the Will?
Kram M, Loaiciga H, Widdowson M … +3 more , Mendez E, Solgi R, Lamar M
Ground Water · 2023 · PMID 37680017 · Publisher ↗
In this issue paper, the authors refine the definition of water sustainability to account for temporal dynamics and spatial variability, identify specific challenges that must be resolved in the very near future to avoid...
In this issue paper, the authors refine the definition of water sustainability to account for temporal dynamics and spatial variability, identify specific challenges that must be resolved in the very near future to avoid catastrophic outcomes on levels ranging from economic disruption to survival of mankind, discuss related policy changes and potential effectiveness, and describe several technologies available to achieve water security and sustainability. While water quality certainly poses formidable challenges, in this piece we emphasize and address challenges associated with dynamic water supply availability. Our future as a society will depend upon how well and how rapidly we navigate these challenges in the coming years. As such, the main objective is to encourage private and public sector practitioners to consider revising existing programs, and to update current industry business models in a manner that promotes expedited solutions, alignment of beneficial goals, and motivates the biggest consumers of water to adopt modern data collection and decision support technologies.
MODFLOW as a Configurable Multi-Model Hydrologic Simulator.
Langevin CD, Hughes JD, Provost AM … +2 more , Russcher MJ, Panday S
Ground Water · 2024 · PMID 37656806 · Publisher ↗
MODFLOW 6 is the latest in a line of six "core" versions of MODFLOW released by the U.S. Geological Survey. The MODFLOW 6 architecture supports incorporation of additional hydrologic processes, in addition to groundwater...
MODFLOW 6 is the latest in a line of six "core" versions of MODFLOW released by the U.S. Geological Survey. The MODFLOW 6 architecture supports incorporation of additional hydrologic processes, in addition to groundwater flow, and allows interaction between processes. The architecture supports multiple model instances and multiple types of models within a single simulation, a flexible approach to formulating and solving the equations that represent hydrologic processes, and recent advances in interoperability, which allow MODFLOW to be accessed and controlled by external programs. The present version of MODFLOW 6 consolidates popular capabilities available in MODFLOW variants, such as the unstructured grid support in MODFLOW-USG, the Newton-Raphson formulation in MODFLOW-NWT, and the support for partitioned stress boundaries in MODFLOW-CDSS. The flexible multi-model capability allows users to configure MODFLOW 6 simulations to represent the local-grid refinement (LGR) capabilities available in MODFLOW-LGR, the multi-species transport capabilities in MT3DMS, and the coupled variable-density capabilities available in SEAWAT. This paper provides a new, holistic and integrated overview of simulation capabilities made possible by the MODFLOW 6 architecture, and describes how ongoing and future development can take advantage of the program architecture to integrate new capabilities in a way that is minimally invasive and automatically compatible with the existing MODFLOW 6 code.
A Novel Semi-Analytical Solution of Over-Damped Slug Test in a Three-Layered Aquifer System.
Cao M, Wen Z, Chen G … +3 more , Hu C, Zhu Q, Jakada H
Ground Water · 2024 · PMID 37646611 · Publisher ↗
The slug test has been commonly used to estimate aquifer parameters. Previous studies on the slug test mainly focused on a single-layer aquifer. However, understanding the interaction between layers is particularly impor...
The slug test has been commonly used to estimate aquifer parameters. Previous studies on the slug test mainly focused on a single-layer aquifer. However, understanding the interaction between layers is particularly important when assessing aquifer parameters under certain circumstances. In this study, a new semi-analytical model on transient flow in a three-layered aquifer system with a partially penetrating well was developed for the slug test. The proposed model was solved using the Laplace transform method and the Goldstein-Weber transform method, where the semi-analytical solution for the model was obtained. The drawdowns of the proposed model were analyzed to understand the impacts of the different parameters on the drawdowns in a three-layered aquifer system. The results indicated that groundwater interactions between the layers have a significant impact on the slug test. In addition, a shorter and deeper well screen as well as a greater permeability ratio between the layers creates a greater interface flow between them, leading to a higher drawdown in the slug test. Finally, a slug test in a three-layered aquifer system was conducted in our laboratory to validate the new model, which indicated that the proposed model performed better in the interpretation of the experimental data than a previous model proposed by Hyder et al. (1994). We also proposed an empirical relationship to qualitatively identify the errors in the application of single-layer model for the analysis of response data in a three-layered aquifer system.
Benefits and Cautions in Data Assimilation Strategies: An Example of Modeling Groundwater Recharge.
Shapiro AM, Day-Lewis FD
Ground Water · 2024 · PMID 37638813 · Publisher ↗
Assimilating recent observations improves model outcomes for real-time assessments of groundwater processes. This is demonstrated in estimating time-varying recharge to a shallow fractured-rock aquifer in response to pre...
Assimilating recent observations improves model outcomes for real-time assessments of groundwater processes. This is demonstrated in estimating time-varying recharge to a shallow fractured-rock aquifer in response to precipitation. Results from estimating the time-varying water-table altitude (h) and recharge, and their error covariances, are compared for forecasting, filtering, and fixed-lag smoothing (FLS), which are implemented using the Kalman Filter as applied to a data-driven, mechanistic model of recharge. Forecasting uses past observations to predict future states and is the current paradigm in most groundwater modeling investigations; filtering assimilates observations up to the current time to estimate current states; and FLS estimates states following a time lag over which additional observations are collected. Results for forecasting yield a large error covariance relative to the magnitude of the expected recharge. With assimilating recent observations of h, filtering and FLS produce estimates of recharge that better represent time-varying observations of h and reduce uncertainty in comparison to forecasting. Although model outcomes from applying data assimilation through filtering or FLS reduce model uncertainty, they are not necessarily mass conservative, whereas forecasting outcomes are mass conservative. Mass conservative outcomes from forecasting are not necessarily more accurate, because process errors are inherent in any model. Improvements in estimating real-time groundwater conditions that better represent observations need to be weighed for the model application against outcomes with inherent process deficiencies. Results from data assimilation strategies discussed in this investigation are anticipated to be relevant to other groundwater processes models where system states are sensitive to system inputs.
Evaluation of Hydraulic Conductivity Estimates from Various Approaches with Groundwater Flow Models.
Sun D, Luo N, Vandenhoff A … +5 more , McCall W, Zhao Z, Wang C, Rudolph DL, Illman WA
Ground Water · 2024 · PMID 37605321 · Publisher ↗
Significant efforts have been expended for improved characterization of hydraulic conductivity (K) and specific storage (S) to better understand groundwater flow and contaminant transport processes. Conventional methods...
Significant efforts have been expended for improved characterization of hydraulic conductivity (K) and specific storage (S) to better understand groundwater flow and contaminant transport processes. Conventional methods including grain size analyses (GSA), permeameter, slug, and pumping tests have been utilized extensively, while Direct Push-based Hydraulic Profiling Tool (HPT) surveys have been developed to obtain high-resolution K estimates. Moreover, inverse modeling approaches based on geology-based zonations, and highly parameterized Hydraulic Tomography (HT) have also been advanced to map spatial variations of K and S between and beyond boreholes. While different methods are available, it is unclear which one yields K estimates that are most useful for high resolution predictions of groundwater flow. Therefore, the main objective of this study is to evaluate various K estimates at a highly heterogeneous field site obtained with three categories of characterization techniques including: (1) conventional methods (GSA, permeameter, and slug tests); (2) HPT surveys; and (3) inverse modeling based on geology-based zonations and highly parameterized approaches. The performance of each approach is first qualitatively analyzed by comparing K estimates to site geology. Then, steady-state and transient groundwater flow models are employed to quantitatively assess various K estimates by simulating pumping tests not used for parameter estimation. Results reveal that inverse modeling approaches yield the best drawdown predictions under both steady and transient conditions. In contrast, conventional methods and HPT surveys yield biased predictions. Based on our research, it appears that inverse modeling and data fusion are necessary steps in predicting accurate groundwater flow behavior.
Performance of Gradient and Gradient-Free Optimizers in Transient Hydraulic Tomography.
Chintala S, Kambhammettu BVNP, Harmya TS
Ground Water · 2024 · PMID 37603229 · Publisher ↗
Sub-surface characterization in fractured aquifers is challenging due to the co-existence of contrasting materials namely matrix and fractures. Transient hydraulic tomography (THT) is proved to be an efficient and robust...
Sub-surface characterization in fractured aquifers is challenging due to the co-existence of contrasting materials namely matrix and fractures. Transient hydraulic tomography (THT) is proved to be an efficient and robust technique to estimate hydraulic (K, K) and storage (S, S) properties in such complex hydrogeologic settings. However, performance of THT is governed by data quality and optimization technique used in inversion. We assessed the performance of gradient and gradient-free optimizers with THT inversion. Laboratory experiments were performed on a two-dimensional, granite rock (80 cm × 45 cm × 5 cm) with known fracture pattern. Cross-hole pumping experiments were conducted at 10 ports (located on fractures), and time-drawdown responses were monitored at 25 ports (located on matrix and fractures). Pumping ports were ranked based on weighted signal-to-noise ratio (SNR) computed at each observation port. Noise-free, good quality (SNR > 100) datasets were inverted using Levenberg-Marquardt: LM (gradient) and Nelder-Mead: NM (gradient-free) methods. All simulations were performed using a coupled simulation-optimization model. Performance of the two optimizers is evaluated by comparing model predictions with observations made at two validation ports that were not used in simulation. Both LM and NM algorithms have broadly captured the preferential flow paths (fracture network) via K and S tomograms, however LM has outperformed NM during validation ( ). Our results conclude that, while method of optimization has a trivial effect on model predictions, exclusion of low quality (SNR ≤ 100) datasets can significantly improve the model performance.
muFlowReacT: A Library to Solve Multiphase Multicomponent Reactive Transport on Unstructured Meshes.
Atteia O, Prommer H, Vlassopoulos D … +2 more , André L, Cohen G
Ground Water · 2024 · PMID 37522260 · Publisher ↗
In this paper we present a new reactive transport code for the efficient simulation of groundwater quality problems. The new code couples the two previously existing tools OpenFoam and PhreeqcRM. The major objective of t...
In this paper we present a new reactive transport code for the efficient simulation of groundwater quality problems. The new code couples the two previously existing tools OpenFoam and PhreeqcRM. The major objective of the development was to transfer and expand the capabilities of the MODFLOW/MT3DMS-family of codes, especially their outstanding ability to suppress numerical dispersion, to a versatile and computationally efficient code for unstructured grids. Owing to the numerous, previously existing transport solvers contained in OpenFoam, the newly developed code achieves this objective and provides a solid basis for future expansions of the code capabilities. The flexibility of the OpenFoam framework is illustrated by the addition of diffusional processes for gaseous compounds in the unsaturated zone and the advection of gases (multiphase transport). The code capabilities and accuracy are illustrated through several examples: (1) a simple 2D case for conservative solute transport under saturated conditions, (2) a gas diffusion case with reactions in the unsaturated zone, (3) a hydrogeologically complex 3D reactive transport problem, and finally (4) the injection of CO into a deep aquifer with acidification being buffered by carbonate minerals.
Impacts of Groundwater Pumping for Hydraulic Fracturing on Aquifers Overlying the Eagle Ford Shale.
Brien JA, Obkirchner GE, Knappett PSK … +3 more , Miller GR, Burnett D, Bhatia M
Ground Water · 2024 · PMID 37507835 · Publisher ↗
Hydraulic fracturing (HF) events consume high volumes of water over a short time. When groundwater is the source, the additional pumping by rig/frack supply wells (RFSWs) may impose costs on owners of other sector wells...
Hydraulic fracturing (HF) events consume high volumes of water over a short time. When groundwater is the source, the additional pumping by rig/frack supply wells (RFSWs) may impose costs on owners of other sector wells (OSWs) by lowering the hydraulic head. The Carrizo-Wilcox aquifer in south Texas is the main source of water for HF of the Eagle Ford Shale (EFS) Play. The objectives are to assess the impacts of groundwater pumping for HF supply on: (1) hydraulic heads in OSWs located nearby an RFSW and (2) volumetric fluxes between layers of the regional aquifer system compared to a baseline model without the effect of RFSW pumping. The study area spans the footprint of the EFS Play in Texas and extends from 2011 to 2020. The pumping schedules of 2500 RFSWs were estimated from reported pumped water volumes to supply 22,500 HF events. Median annual drawdowns in OSWs ranged from 0.2 to 6.6 m, whereas 95th percentile annual drawdowns exceeded 20 m. The magnitudes of drawdown increased from 2011 to 2020. Of the four layers that comprise the Carrizo-Wilcox aquifer, the upper Wilcox was the most intensively pumped for HF supply. During the peak HF year of 2014, the net flux to the upper Wilcox was 292 Mm compared to the baseline net flux for the same year of 278 Mm-a relative gain of 14 Mm. Pumping for HF supply has the potential to negatively impact nearby OSWs by capturing water from adjacent aquifer layers.
GroMoPo: A Groundwater Model Portal for Findable, Accessible, Interoperable, and Reusable (FAIR) Modeling.
Zipper S, Befus KM, Reinecke R … +10 more , Zamrsky D, Gleeson T, Ruzzante S, Jordan K, Compare K, Kretschmer D, Cuthbert M, Castronova AM, Wagener T, Bierkens MFP
Ground Water · 2023 · PMID 37483111 · Publisher ↗
Abstract loading — click title to view on PubMed.
Inorganic Hydrogeochemistry in the 21st Century.
Zhu C, Fryar AE, Apps J
Ground Water · 2024 · PMID 37482948 · Publisher ↗
Chemical and isotopic processes occur in every segment of the hydrological cycle. Hydrogeochemistry-the subdiscipline that studies these processes-has seen a transformation from "witch's brew" to credible science since 2...
Chemical and isotopic processes occur in every segment of the hydrological cycle. Hydrogeochemistry-the subdiscipline that studies these processes-has seen a transformation from "witch's brew" to credible science since 2000. Going forward, hydrogeochemical research and applications are critical to meeting urgent societal needs of climate change mitigation and clean energy, such as (1) removing CO from the atmosphere and storing gigatons of CO in soils and aquifers to achieve net-zero emissions, (2) securing critical minerals in support of the transition from fossil fuels to renewable energies, and (3) protecting water resources by adapting to a warming climate. In the last two decades, we have seen extensive activity and progress in four research areas of hydrogeochemistry related to water-rock interactions: arsenic contamination of groundwater; the use of isotopic and chemical tracers to quantify groundwater recharge and submarine groundwater discharge; the kinetics of chemical reactions and the mineral-water interface's control of contaminant fate and transport; and the transformation of geochemical modeling from an expert-only exercise to a widely accessible tool. In the future, embracing technological advances in machine learning, cyberinfrastructure, and isotope analytical tools will allow breakthrough research and expand the role of hydrogeochemistry in meeting society's needs for climate change mitigation and the transition from fossil fuels to renewable energies.
Control of Structural Landform Evolution on Karst Groundwater Cycle in a Large-Scale Anticlinorium.
Fan Y, Ji H, Lu R … +2 more , Wan J, Huang K
Ground Water · 2024 · PMID 37401104 · Publisher ↗
Structural landform evolution and hydrogeochemical analyses are crucial for understanding the characteristics of karst groundwater systems and the development of deep karst formed by complex aquifers in a tectonic collis...
Structural landform evolution and hydrogeochemical analyses are crucial for understanding the characteristics of karst groundwater systems and the development of deep karst formed by complex aquifers in a tectonic collision zone. Detailed structural landform evolution analysis was carried out along the large-scale anticlinorium to investigate the temporal evolution of karst aquifer systems and karstification. Results showed that the tectonic activity included weak horizontal compression and slow vertical uplift during the Triassic to Middle Jurassic, forming a denuded clastic platform. This period was mainly preserved in the geological record as burial karst. From the Late Jurassic to the Early Cretaceous, the study area was strongly compressed by S-N-trending stress, and developed E-W-trending high-angle imbricate thrust structures, which controlled the formation of folded and fault-blocked mountains. Vertical multilayered strata underwent a strong horizontal extrusion, forming a large-scale anticlinorium with secondary folds and faults. With the exposure of carbonate rocks due to rapid crustal uplift, karst began to develop, forming a vertical multilayer karst aquifer system and controlling the distribution of karst groundwater. The Fangxian faulted basin was formed from the Late Cretaceous to the Paleogene, whereby landforms were dominated by intermountain basins. Slow crustal uplift caused the retreat of the denudation line to the east, leading to an increase in hydrodynamic conditions and karstification, and the initiation of early karst groundwater systems. Since the Neogene, intermittent and rapid crustal uplift has led to the deepening of rivers, resulting in the formation of peak clusters and canyons, the development of deep karst, and the complete formation of karst groundwater systems. Combined with hydrogeochemical and borehole data, local, intermediate, and regional karst groundwater systems were identified. It has vital significance to the geological route selection or construction of deep-buried tunnels and the utilization of karst groundwater.
PEST and AEM Modeling for Data Acquisition Planning.
McLane C
Ground Water · 2024 · PMID 37395050 · Publisher ↗
A well-planned field data collection program should be designed to (1) collect a sufficient set of data of the right types at the right locations, and (2) collect a parsimonious set of data to avoid unnecessary costs. Co...
A well-planned field data collection program should be designed to (1) collect a sufficient set of data of the right types at the right locations, and (2) collect a parsimonious set of data to avoid unnecessary costs. Combining PEST and a simple analytic element method (AEM) groundwater flow model for the site of interest provides a relatively simple, low-cost method of developing such a program. AEM models are well suited to this approach because they are quick to develop yet hydraulically accurate, reducing impacts on project budgets at early data collection planning stages; and quick to run, solving rapidly for the many iterations that PEST requires to generate good parameter estimates. This article shows two examples of this method: one for a steady state watershed model, and one for a transient pumping test project to demonstrate that PEST coupled with a simple AEM model that sketches out the key features of a site conceptual model can be an efficient tool in planning key parts of a hydrogeologic site investigation.
Automated Estimation of Aquifer Parameters from Arbitrary-Rate Pumping Tests in Python and MATLAB.
Benson DA
Ground Water · 2024 · PMID 37392403 · Publisher ↗
Inspired by the analysis by Mishra et al. (2012) of variable pumping rate tests using piecewise-linear reconstructions of the pumping history, this article contains a derivation of the convolutional form of pumping tests...
Inspired by the analysis by Mishra et al. (2012) of variable pumping rate tests using piecewise-linear reconstructions of the pumping history, this article contains a derivation of the convolutional form of pumping tests in which the pumping history may take any possible form. The solution is very similar to the classical Theis (1935) equation but uses the Green's function for a pumped aquifer given by taking the time derivative of the well function . This eliminates one integration inside another and renders the convolution including the pumping history about as computationally demanding as calculating the well function alone, so that the convolution can be completed using handy mathematical software. It also allows nonlinear well losses, and because an easily-computed deterministic model exists for all data points and pumping history, an objective function may include all data, so that errors are reduced in calculating any nonlinear-well losses. In addition, data from multiple observation wells may be used simultaneously in the inversion. We provide codes in MATLAB and Python to solve for drawdown resulting from an arbitrary pumping history and compute the optimal aquifer parameters to fit the data. We find that the subtleties in parameter dependencies and constructing an appropriate objective function have a substantial effect on the interpreted parameters. Furthermore, the optimization from step-drawdown tests is typically nonunique and strongly suggests that a Bayesian inversion should be used to fully estimate the joint probability density of the parameter vector.
Study on Permeability Calculation Method Based on J Function and Fractal Theory.
Lu G, Lai F, Li B
Ground Water · 2024 · PMID 37392127 · Publisher ↗
Permeability is a required parameter for studying aquifer properties. However, for sandstone aquifers with low permeability, it is difficult to measure permeability directly through experiments. Based on fractal theory a...
Permeability is a required parameter for studying aquifer properties. However, for sandstone aquifers with low permeability, it is difficult to measure permeability directly through experiments. Based on fractal theory and the J function, a new method to calculate the permeability of a sandstone aquifer is derived. This work first solves the J function under each water saturation according to its definition. Combined with mercury pressure data, the J function and logarithmic curve equation of water saturation are then fitted by the drawing method, and the fractal dimension and tortuosity of the aquifer are further solved. Finally, the aquifer's permeability is calculated using the new permeability calculation method. To verify the accuracy of the proposed method, 15 rock samples from the Chang 7 Group, Ordos Basin, are taken as research objects. The permeability is calculated using the new method combined with mercury injection data and aquifer characteristic parameters, and the results are compared with the real permeability. The relative error of most samples is <20%, which shows the permeability calculated by this method is accurate and reliable. The effects of fractal dimension, tortuosity, and porosity on permeability are also analyzed.
Community Cloud Computing Infrastructure to Support Equitable Water Research and Education.
Castronova AM, Nassar A, Knoben W … +3 more , Fienen MN, Arnal L, Clark M
Ground Water · 2023 · PMID 37358302 · Publisher ↗
Abstract loading — click title to view on PubMed.
Estimating Groundwater Pumping for Irrigation: A Method Comparison.
Brookfield AE, Zipper S, Kendall AD … +2 more , Ajami H, Deines JM
Ground Water · 2024 · PMID 37345502 · Publisher ↗
Effective groundwater management is critical to future environmental, ecological, and social sustainability and requires accurate estimates of groundwater withdrawals. Unfortunately, these estimates are not readily avail...
Effective groundwater management is critical to future environmental, ecological, and social sustainability and requires accurate estimates of groundwater withdrawals. Unfortunately, these estimates are not readily available in most areas due to physical, regulatory, and social challenges. Here, we compare four different approaches for estimating groundwater withdrawals for agricultural irrigation. We apply these methods in a groundwater-irrigated region in the state of Kansas, USA, where high-quality groundwater withdrawal data are available for evaluation. The four methods represent a broad spectrum of approaches: (1) the hydrologically-based Water Table Fluctuation method (WTFM); (2) the demand-based SALUS crop model; (3) estimates based on satellite-derived evapotranspiration (ET) data from OpenET; and (4) a landscape hydrology model which integrates hydrologic- and demand-based approaches. The applicability of each approach varies based on data availability, spatial and temporal resolution, and accuracy of predictions. In general, our results indicate that all approaches reasonably estimate groundwater withdrawals in our region, however, the type and amount of data required for accurate estimates and the computational requirements vary among approaches. For example, WTFM requires accurate groundwater levels, specific yield, and recharge data, whereas the SALUS crop model requires adequate information about crop type, land use, and weather. This variability highlights the difficulty in identifying what data, and how much, are necessary for a reasonable groundwater withdrawal estimate, and suggests that data availability should drive the choice of approach. Overall, our findings will help practitioners evaluate the strengths and weaknesses of different approaches and select the appropriate approach for their application.
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