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The accessibility and deployment of complex hydrological models remain significant challenges in water resource management and research. This study presents a comprehensive workflow for converting Python-based hydrological models into web APIs, addressing the need for more accessible and interoperable modeling tools. The workflow leverages modern web technologies and containerization to streamline the deployment process. The workflow was applied to three distinct models: a GRACE downscaling model, a synthetic time series generator, and a MODFLOW groundwater model. The implementation process for each model was completed in approximately 15 min with a reliable internet connection, demonstrating the efficiency of the approach. The resulting APIs provide standardized interfaces for model execution, progress tracking, and result retrieval, facilitating integration with various applications. This workflow significantly reduces barriers to model deployment and usage, potentially broadening the user base for sophisticated hydrological tools. The approach aligns hydrological modeling with contemporary software development practices, opening new avenues for collaboration and innovation. While challenges such as performance scaling and security considerations remain, this work provides a blueprint for making complex hydrological models more accessible and operational, paving the way for enhanced research and practical applications in hydrology. [ABSTRACT FROM AUTHOR]

Under varying flow rate conditions, the transport and retention of polydisperse microplastics (MPls), with an average particle size of 16 ± 6 µm, were investigated in saturated porous media. First-order reversible and irreversible kinetic sorption models were used to describe the sorption kinetics. Sensitivity analyses provided insight into the effects of each sorption parameter. Both numerical modeling and experimental measurements were utilized to evaluate the retention rates of sand filters. The influence of flow rate on sorption was reflected in variations in the distribution coefficient (Kd), the mass transfer coefficient (β), and the irreversible sorption rate (K1). Lower flow rates were associated with higher Kd and β values, indicating increased sorption and reduced mass transfer rates. An increase in Kd resulted in a more gradual sorption process, with a decrease in peak concentration, whereas changes in β had a comparatively smaller impact on sorption rate and peak concentration. Lower K1 values were linked to higher peak concentrations and decreased retention efficiency. Numerical modeling revealed retention rates of 28 ± 1% at a flow rate of 31 mL min−1 and 17 ± 1% at 65 mL min−1. The introduction of MPls into saturated sand environments modifies the transport dynamics within the medium. Consequently, these alterations affect the hydrological characteristics of porous media, impacting groundwater quality and agricultural output. The mean absolute error (MAE) of 6% between the modeled and observed retention rates indicated a high level of accuracy. This study underscores the importance of examining retention efficiency and the accuracy of numerical models in understanding MPl transport in porous media. [ABSTRACT FROM AUTHOR]

Examining the condition of groundwater resources and the impact of droughts is valuable for effective water resources management. Today, machine learning (ML) models are recognized as one of the useful tools in time series predictions. In this study, the groundwater condition of one of the most important aquifers in northwest Iran was investigated using MODFLOW, followed by estimating the groundwater resource index (GRI) utilizing the multivariate adaptive regression spline (MARS) and least squares support vector regression (LSSVR) for a period between 2001 and 2019. Meteorological and hydrological drought indicators along with precipitation and flow rate were used as input variables for prediction. The simulation results revealed a groundwater level decrease since the aquifer withdrawal amount is more than the recharge amount. Besides, results showed that there is a limited interaction between surface water and groundwater resources, mainly caused by the decrease in the river flow and aquifer groundwater level drop. Both ML models performed well in GRI estimation, using groundwater flow, streamflow drought index, standardized precipitation index, and runoff as input variables. The performance of the MARS model with RMSE, MAE, and NSE error evaluation criteria of 0.37, − 0.19, and 0.83, respectively, exerted slightly better results than LSSVR with RMSE, MAE, and NSE of 0.48, − 0.06, and 0.80, respectively. The findings reveal the appropriate performance of both models in forecasting drought indicators, highlighting the necessity of using ML models in hydrology and drought prediction problems. [ABSTRACT FROM AUTHOR]

The area of Sia Kouanza in the Sahel of southwestern Niger is a potential location for expanding agriculture through irrigation with groundwater. Agriculture is key to supporting smallholders and promoting food security. As plans proceed, questions include how much water is available, how is groundwater replenished, many hectares to develop, and where to locate the wells. While these questions can be addressed with a model, it is difficult to find detailed procedures, especially when data are scarce. How can we use existing information to develop a model of a natural system where groundwater development will take place? We describe an approach that can be employed in data-scarce areas where similar questions are being asked. The approach includes setting details; conceptual model development; water balance; numerical code MODFLOW; model construction, calibration, and statistics; and result interpretation. Conceptual model component estimates are derived from field data: recharge, evapotranspiration, wetlands discharge, existing extraction, and river stages. When field data are not available or scarce, we employ other sources and describe how they are validated with field data or analog sites. The calibrated steady-state model gives a water balance of 22 × 106 m3/yr with inflows (recharge 22 × 106 m3/yr) and outflows (extraction 7.2 × 105 m3/yr, wetlands 5.7 × 106 m3/yr, evapotranspiration 11.9 × 106 m3/yr). The model is a point of departure; approaches for transient and predictive models, which can be used to simulate changes in irrigation pumping volumes and drought, for example, will be described subsequently. [ABSTRACT FROM AUTHOR]

Water scarcity is one of the major critical affecting arid climate countries. In addition, population growth and climate change are threatening the sustainable development of water resources in the upcoming decades. Therefore, managing groundwater can solve water scarcity such that sustainable development is ensured for future generations. Hence, it is crucial to assess the current quantity of groundwater by analyzing groundwater variables. Thus, natural groundwater recharge could be utilized as an indicator to assess groundwater quantity conditions. This study aims to estimate natural groundwater recharge in an arid unconfined aquifer. El-Qaa plain in Sinai, Egypt was chosen as a case study. Recharge was estimated taking into consideration spatial and temporal variability. To accomplish this, the WetSpass (Water and Energy Transfer between Soil, Plants, and Atmosphere under quasi-Steady State) model was applied. The model was run using morphological, landuse – land cover and climate data from 1986 to 2015 with a monthly time step. To calibrate the model, the isotope signature of δ18O and δ2 H of water was analyzed to determine the natural groundwater recharge of the aquifer. The obtained recharge value was utilized as a reference value for the calibration process. The results were validated using a finite-difference groundwater flow model (MODFLOW). The recharge values were imported to MODFLOW followed via a transient run from 2000 to 2011. The validation was conducted by comparing the simulated groundwater level with the observed ones. After validation process, the inter-annual and seasonal variability of recharge were determined, and a relationship between recharge and other hydrological parameters was deduced. In addition, the recharge distribution was mapped to depict the recharge spatial variability. The results show that the current recharge rate ranges from approximately 8.10 to 16.62 mm/yr, with a mean annual recharge rate of nearly 12.36 mm/yr. The study might be useful for hydrogeologists for determining potential recharge in the study area, groundwater modelers for developing a reliable groundwater flow model, and decision-makers for planning appropriate future sustainable development through water resources management.

The Nile Delta aquifer stands as Egypt’s second primary freshwater source following the Nile River. Its replenishment deriveed from various sources, including the Nile branches, the surface irrigation networks, and the infiltration of excess irrigation water. The expanded demand for irrigation water causes water shortages at the canal tails of some irrigation canals across Egypt. Farmers have resorted to addressing this issue by illegally excavating shallow wells, employing them in times when surface water is inaccessible. Among the national action plans to improve water availability at canal tails is the lining of distributary canals. However, this intervention potentially obstructs the natural replenishment source of the Nile Delta aquifer, consequently contributing to the deterioration of groundwater quality. Hence, this research aims to evaluate the impacts of lining distributary canals on groundwater status through numerical modeling. Utilizing the MODFLOW package, the study determines the natural infiltration rates from the canals into the adjoining groundwater system. Two prevalent hydrological conditions in Egypt were selected for numerical modeling. The first case study focuses on a Canal, located in Qalyoubia governorate, represents the semi-confined aquifer conditions prevalent in the Nile Delta. The second case study is a Canal, situated in Sharqia governorate, represents the phreatic aquifer conditions present in the Nile Delta. Piezometers were implemented to determine the groundwater levels and for the calibration process. The calibrated models were employed to simulate the expected impacts of canal lining for each case and contrasted with pre-lining infiltration rates. Findings indicate that while canal lining effectively reduces water seepage into shallow groundwater in sandy soils, it is of little avail in clayey top soils. The research recommends implementing integrated water resource management to mitigate the possible impacts of lining. It also suggests prioritizing regular maintenance practices for canal linings, especially in areas with sandy soils.

Abstract Examining the condition of groundwater resources and the impact of droughts is valuable for effective water resources management. Today, machine learning (ML) models are recognized as one of the useful tools in time series predictions. In this study, the groundwater condition of one of the most important aquifers in northwest Iran was investigated using MODFLOW, followed by estimating the groundwater resource index (GRI) utilizing the multivariate adaptive regression spline (MARS) and least squares support vector regression (LSSVR) for a period between 2001 and 2019. Meteorological and hydrological drought indicators along with precipitation and flow rate were used as input variables for prediction. The simulation results revealed a groundwater level decrease since the aquifer withdrawal amount is more than the recharge amount. Besides, results showed that there is a limited interaction between surface water and groundwater resources, mainly caused by the decrease in the river flow and aquifer groundwater level drop. Both ML models performed well in GRI estimation, using groundwater flow, streamflow drought index, standardized precipitation index, and runoff as input variables. The performance of the MARS model with RMSE, MAE, and NSE error evaluation criteria of 0.37, − 0.19, and 0.83, respectively, exerted slightly better results than LSSVR with RMSE, MAE, and NSE of 0.48, − 0.06, and 0.80, respectively. The findings reveal the appropriate performance of both models in forecasting drought indicators, highlighting the necessity of using ML models in hydrology and drought prediction problems.

In arid regions, the optimal utilization of river channels to collect rainwater resources can effectively alleviate the problem of water scarcity. This paper employs visual MODFLOW software to simulate the infiltration volume of rainwater under different schemes, with the objective of identifying the optimal infiltration volume. The results indicate that the infiltration volume of rainwater is 0.6, 79.7, 36.5, 62, and 10,000 m3 under different design schemes. COMSOL software is employed to simulate the infiltration situation of rainwater under different schemes, and the scheme with the most favourable infiltration effect is identified. The simulation results indicate that scenarios 2, 4, and 5 demonstrate superior early-stage infiltration performance. Ultimately, the optimal infiltration scheme is selected by integrating the infiltration volume, infiltration effect, construction, economic, and ecological factors to achieve the objective of enhancing rainwater harvesting and utilization. This study offers effective and reasonable measures for addressing the challenge of water resources management in arid regions. It provides suitable reference schemes for river channel rainwater storage projects and offers innovative approaches to rainwater resource utilization, thereby contributing to the alleviation of water scarcity in arid areas.

Water scarcity poses a significant challenge in arid and semi-arid regions, necessitating a focused exploration of groundwater resources. Egypt, confronted with various water challenges, particularly in its Western Desert, relies heavily on groundwater as the exclusive water source due to the presence of the Nubian Sandstone aquifer. Effective groundwater management in this region is imperative. This study delves into the hydrogeological characteristics of the Nubian Sandstone aquifer system (NSAS) in the prominent New Valley Oases—Kharga, Dakhla, and Farafra—where agricultural activities heavily depend on groundwater. The primary objective entails a meticulous temporal assessment of the impact of groundwater development on aquifer behavior, groundwater levels, and drawdown. Employing a remote sensing approach, agricultural expansion from 1995 to 2020 was scrutinized. The Visual MODFLOW package served as a robust tool for simulating groundwater flow in the study areas. Noteworthy findings reveal an upward trajectory in agricultural crop areas, escalating by approximately 6% from 1740 km² in 1995 to 1850 km² in 2020. Concurrently, drawdown, influenced by current groundwater extraction, is anticipated to range from 0.5 to 5 meters per year. To ensure the sustainable development of these areas, stringent regulations must be implemented, underscoring the imperative for judicious groundwater management practices. This research underscores the critical need for informed decision-making and proactive measures to address the evolving dynamics of groundwater resources in the New Valley Oases.

This study presents the development of a comprehensive three-dimensional groundwater flow model for the Erbil Basin utilizing the Groundwater Modeling System (GMS). The Erbil Basin, situated in the Kurdistan Region of Iraq, is a vital water resource area facing increasing water demands and environmental challenges. The three-dimensional nature of the groundwater flow system is crucial for accurately understanding and managing water resources in the basin. The modeling process involved data collection, geological and hydrogeological characterization, conceptual model development, and numerical simulation using GMS software MODFLOW 2000 package. Various parameters such as hydraulic conductivity, recharge rates, and boundary conditions were integrated into the model to represent the complex hydrogeological conditions of the basin. Model calibration was performed by comparing simulated groundwater levels with observed data from monitoring wells across the basin, using the automatic calibration method of automated Parameter Estimation (PEST). Pilot points were applied to adjust the hydraulic conductivity in the model area spatially. Sensitivity analysis was conducted to assess the influence of key parameters on model predictions and to identify areas of uncertainty. The developed three-dimensional groundwater flow model provides valuable insights into the dynamics of groundwater flow, recharge-discharge mechanisms, and potential impacts of future scenarios such as climate change and water resource management strategies. It serves as a useful tool for decision-makers, water resource managers, and researchers to evaluate different management scenarios and formulate sustainable groundwater management policies for the Erbil Basin. In conclusion, this study demonstrates the effectiveness of using GMS for developing three-dimensional groundwater flow models in complex hydrogeological settings like the Erbil Basin, contributing to improved understanding and management of groundwater resources in the region.

Groundwater, essential for supplying drinking water to half of the global population and supporting nearly half of all irrigation needs, faces significant contamination risks. These risks pose serious threats to human health and ecosystem integrity, driven by increasing pressures from both concentrated and diffuse pollution sources, as well as from growing exploitation. The presented research was conducted with the dual objectives of identifying sources of nitrate contamination (up to 128.1 mg/L) in an oxic groundwater source (Perkićevo, Serbia) and proposing an optimal extraction regimen to ensure a sufficient supply of potable water. Correlations between chemical elements' concentrations and principal component analysis (PCA) indicated a significant relationship between anthropogenic impact indicators (NO3−, Na+, B, Cl−, SO42−, KMnO4 consumption, and electroconductivity), unambiguously showing that groundwater quality was primarily impacted by untreated sewage inflow and confirming nitrate's tracer behavior in oxic environments. The spatial distribution of selected parameter concentration gradients highlighted the expansion and distribution of the contamination front. A numerical groundwater flow model (Vistas 4 and Modflow) was applied to determine the groundwater flow direction and the quantity of groundwater originating from different parts of the investigated area. Through four simulated groundwater extraction scenarios, Scenario 2, with an average extraction rate of 80 L/s from 12 wells, and Scenario 3, with an average extraction rate of 75 L/s and 4 additional wells, were identified as the most optimal, providing a sufficient quantity of adequately sanitary water. [ABSTRACT FROM AUTHOR]

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Inverse problems in hydrogeology pose a great challenge for modelers as they are ill-posed, resulting in a non-unique solution. High computational resources are needed for the calibration process, especially in the case of highly parameterized aquifers like karst limestone, characterized by significant heterogeneity. The nullspace Monte Carlo (NSMC) is a parameter-constrained Monte Carlo approach that can be used to quantify uncertainty, as it produces a set of solutions that calibrate the model. This method is used to assess uncertainty in the calibration of a karst aquifer in Qatar, which has high heterogeneity. Pilot points were used to reflect the geostatistics of the calibrated field, and the calibration results at these points were interpolated over the aquifer area using kriging. The NSMC was then used to produce 200 realizations of the null-space parameter field using the constrained random variable of hydraulic conductivity. The null-space realizations were then incorporated into the parameter space derived from the calibrated model. Statistical analysis of the calibrated hydraulic conductivity revealed a variation ranging from 0.1 to 350 m/d, indicating a considerable variability in the aquifer's hydraulic parameters. The areas with high hydraulic conductivity were concentrated in the central and eastern parts of the aquifer, and these same areas exhibited a high standard deviation. Based on the findings of this study, while the NSMC method is effective for uncertainty analysis in solving inverse problems, it is important to note that a considerable number of runs are necessary to reach the threshold of calibration error. This is because of the significant non-linearity inherent in the karst aquifer. [ABSTRACT FROM AUTHOR]

Water scarcity poses a significant challenge in arid and semi-arid regions, necessitating a focused exploration of groundwater resources. Egypt, confronted with various water challenges, particularly in its Western Desert, relies heavily on groundwater as the exclusive water source due to the presence of the Nubian Sandstone aquifer. Effective groundwater management in this region is imperative. This study delves into the hydrogeological characteristics of the Nubian Sandstone aquifer system (NSAS) in the prominent New Valley Oases--Kharga, Dakhla, and Farafra--where agricultural activities heavily depend on groundwater. The primary objective entails a meticulous temporal assessment of the impact of groundwater development on aquifer behavior, groundwater levels, and drawdown. Employing a remote sensing approach, agricultural expansion from 1995 to 2020 was scrutinized. The Visual MODFLOW package served as a robust tool for simulating groundwater flow in the study areas. Noteworthy findings reveal an upward trajectory in agricultural crop areas, escalating by approximately 6% from 1740 km² in 1995 to 1850 km² in 2020. Concurrently, drawdown, influenced by current groundwater extraction, is anticipated to range from 0.5 to 5 meters per year. To ensure the sustainable development of these areas, stringent regulations must be implemented, underscoring the imperative for judicious groundwater management practices. This research underscores the critical need for informed decision-making and proactive measures to address the evolving dynamics of groundwater resources in the New Valley Oases. [ABSTRACT FROM AUTHOR]

This study presents the development of a comprehensive three-dimensional groundwater flow model for the Erbil Basin utilizing the Groundwater Modeling System (GMS). The Erbil Basin, situated in the Kurdistan Region of Iraq, is a vital water resource area facing increasing water demands and environmental challenges. The three-dimensional nature of the groundwater flow system is crucial for accurately understanding and managing water resources in the basin. The modeling process involved data collection, geological and hydrogeological characterization, conceptual model development, and numerical simulation using GMS software MODFLOW 2000 package. Various parameters such as hydraulic conductivity, recharge rates, and boundary conditions were integrated into the model to represent the complex hydrogeological conditions of the basin. Model calibration was performed by comparing simulated groundwater levels with observed data from monitoring wells across the basin, using the automatic calibration method of automated Parameter Estimation (PEST). Pilot points were applied to adjust the hydraulic conductivity in the model area spatially. Sensitivity analysis was conducted to assess the influence of key parameters on model predictions and to identify areas of uncertainty. The developed three-dimensional groundwater flow model provides valuable insights into the dynamics of groundwater flow, recharge-discharge mechanisms, and potential impacts of future scenarios such as climate change and water resource management strategies. It serves as a useful tool for decision-makers, water resource managers, and researchers to evaluate different management scenarios and formulate sustainable groundwater management policies for the Erbil Basin. In conclusion, this study demonstrates the effectiveness of using GMS for developing three-dimensional groundwater flow models in complex hydrogeological settings like the Erbil Basin, contributing to improved understanding and management of groundwater resources in the region. [ABSTRACT FROM AUTHOR]

Metropolitan Tuguegarao Water District is one of Northern Luzon's leading groundwater consumers, averaging a monthly extraction of 1.43 million cubic meters. Since its inception, the water supply system has relied mainly on groundwater, triggering well sources to deteriorate. While recharge through soil moisture accounting is sufficient for safe yield estimation, a groundwater flow model was created to account for the spatiotemporal distribution of groundwater levels in response to hydraulic and hydrologic stresses. MODFLOW, a finite-difference model, aided in the development of local grids from a regional basin--the Cagayan Valley Aquifer System. A three-dimensional numerical flow model was satisfactorily calibrated, with the goodness offit between the simulated and observed heads determined through three statistical indices: Mean Absolute Error (0.5376 m), Root-Mean-Squared Error (0.8061 m), and Normalized Root-Mean-Squared Error (2.23%). The model simulated a 10.60% recharge from rainfall for the regional basin, which is comparable to the average recharge rate estimated by the Department of Environment and Natural Resources. Continuous pumping demonstrated head reductions that exceeded critical levels in four wells at current rates, 12 wells at adjusted rates, and five wells affected by pumping the proposed wells. Notably, four production wells, which constitute 31% of the present groundwater production, remained below critical levels. With the proposed surface water facility, however, groundwater production may be reduced up to 63%, allowing for the resource to recover. The findings of this research on all model scenarios showed that groundwater levels will decrease in the coming years. Thus, efficient planning for sustainable resource use is crucial. This study presents the relevance of numerical hydraulic analysis for a more comprehensive groundwater resource assessment. [ABSTRACT FROM AUTHOR]

Alluvial plains represent hydrological systems where the aquifer and the associated stream network are in hydraulic communication. In many instances, the stream network is the primary factor controlling water table variability and groundwater circulation. When effective meteoric recharge is scarce, water inflows from the river allow for aquifer exploitation by pumping wells. In addition, the river affects the propagation of the cone of depression and may limit its expansion. The study aimed to characterize the groundwater circulation in the Benevento Plain (southern Italy), which is affected by anthropogenic stresses due to pumping and aquifer-river interactions. To this end, we combined several methods to maximize the information achievable from hydrological monitoring, involving time series analysis and analytical models. We employed cross-correlation and time series processing to assess whether river flow variability could explain the observed water table variability. We also performed numerical simulations to investigate the specific contributions of aquifer-river interactions, effective meteoric recharge, and pumping to groundwater circulation. The simulations showed that the pumped groundwater comes partially from the river and that the latter represents a strong hydrological boundary, which limits the expansion of the cone of depression induced by wells. Analyses highlighted that the river controls groundwater variability and circulation in the Benevento Plain, while meteoric recharge has a negligible role. These findings are crucial for managing and protecting the local aquifer, which supplies water to one of the main inland areas of the southern Apennine, and they could be useful for other similar area worldwide. [ABSTRACT FROM AUTHOR]

Groundwater (GW) emerges as a sustainable resource to meet water demand, yet current GW reservoirs fall short of projected population needs. Artificial GW recharge, bolstered by Geographical Information System (GIS) and Remote Sensing (RS) technologies, stands out as a pivotal solution. Examining Aurangabad district in Maharashtra, India the study uncovers distinct challenges: Aurangabad faces escalating water demand due to population growth, leading to GW over exploitation. Leveraging hydrogeological parameters, rainfall analysis, and GW availability, the study proposes tailored GW recharge techniques. Utilizing MODFLOW simulation, the study explores diverse recharge rates and existing GW availability, showcasing promising results. Integration of stream augmentation, bladder pillow tank methods, and dug well recharge is examined via GIS and RS techniques. Simulation outcomes project significant GW level increases (11.55–23.70 m) with varying recharge rates, effectively meeting region-specific water demand projections. The findings underscore the imperative of sustainable water management practices and technological advancements in addressing water scarcity crises. HIGHLIGHTS Groundwater recharge using GIS and RS.; Parameters to select proper method of GW recharging using like hydrogeological data, and rainfall data.; Stream augmentation and bladder pillow method.; Three cases with different percentages of available GW.; Solving GW depletion problem.;

Abstract This study presents a meticulously edited article that assesses the uncertainty associated with contamination dispersion in a porous aquifer environment. The article employs a conceptual model incorporating finite difference flow modeling and particle tracking methods grounded in particle movement theory within groundwater flow. The groundwater flow model utilizes an automatic calibration technique, PES, and independent verification, to minimize statistical discrepancies in the optimized parameters. The statistical summary of the model output reveals the average pollution concentration in the study area, specifically the landfill aquifer in northern Iran. The results indicate that the initial contamination value at the boundaries is zero, whereas 91,802 units are discharged into the sea. Moreover, approximately 3,317,290,003 pollution units have been extracted from pumping wells along the contamination plume over 10 years. Furthermore, the drainage network releases 1,778,680,001 pollution units, resulting in a net outflow of 5,082,740,007 units from the same drainage network. Additionally, 9,912,180,003 units were discharged from the leaky boundaries. It should be noted that these statistics can be reversed depending on the specified period. The difference between the input and output pollution values in the study area indicates a net accumulation of 8192 units. To analyze the sensitivity of contamination dispersion in the porous aquifer environment and the variations in coastal drainage patterns obtained from the finite difference simulation, the explicit and implicit methods, as well as the random walk particle tracking method, were investigated in a portion of the basin area using the South Side Implicit method. One of the main objectives of this sensitivity analysis is to evaluate the results of the uncalibrated qualitative model and examine the particle dispersion in the adjacent area of the contaminated landfill region to assess the error of the proposed model by developing a limited test. The calculated error or computational difference between the explicit and implicit methods and the applet model is considered negligible. For example, the calculated error between the explicit and backward methods and the applet model ranges from 0.086 to 0.372 units for a concentration interval of 0.512 units and 0.680 units for a time interval 0.537. Therefore, the computational differences are not significant. Furthermore, based on theoretical sensitivity analysis of contamination dispersion, the laboratory model demonstrates that the flow direction in this modeling is from west to east, as expected.

Currently, the demand for water is rising, and as a result, the groundwater is declining. Water supplies are not sufficient for agricultural productivity, environmental preservation, or ecosystem services, resulting in an unbalanced water budget in the basin. The goal of this paper is to assess the groundwater recharge in the Jedeb sub-basin using WetSpass-MODFLOW coupling. A spatially distributed water balance model is developed to simulate long-term average recharge depending on land cover, soil texture, topography, and hydro meteorological parameters. The groundwater model is iteratively connected to the recharge model in order to simulate recharge. This means that the depth of the groundwater affects the recharge estimate and vice versa. The average yearly evapotranspiration, surface runoff, and groundwater recharge were determined using WetSpass-M to be 574, 898, and 99 mm, respectively. Groundwater recharge accounted for 6.3% of precipitation, while actual evapotranspiration and surface runoff accounted for 36.4% and 57% of precipitation, respectively. In such seasonal variations, the groundwater level in the Jedeb Sub-basin was studied under various stress conditions (dry season, wet season, and annually). The groundwater level distribution varied from 2,052.3 to 3,063.06 m in the summer stress period (recharge). While in the winter stress period (recharge), the groundwater level varied from 2,051.41 to 3,061.92 m, and the groundwater level due to the annual stress period (recharge) varied from 2,053.76 to 3,064.5 m. With a correlation coefficient of.89, which is an acceptable fit between the simulated and observed heads in steady state for all stress periods (summer, winter, and annual recharge). The contribution of this study could be used as baseline information for regional water resource experts, policymakers, and researchers for further investigation. [ABSTRACT FROM AUTHOR]

This study presents a meticulously edited article that assesses the uncertainty associated with contamination dispersion in a porous aquifer environment. The article employs a conceptual model incorporating finite difference flow modeling and particle tracking methods grounded in particle movement theory within groundwater flow. The groundwater flow model utilizes an automatic calibration technique, PES, and independent verification, to minimize statistical discrepancies in the optimized parameters. The statistical summary of the model output reveals the average pollution concentration in the study area, specifically the landfill aquifer in northern Iran. The results indicate that the initial contamination value at the boundaries is zero, whereas 91,802 units are discharged into the sea. Moreover, approximately 3,317,290,003 pollution units have been extracted from pumping wells along the contamination plume over 10 years. Furthermore, the drainage network releases 1,778,680,001 pollution units, resulting in a net outflow of 5,082,740,007 units from the same drainage network. Additionally, 9,912,180,003 units were discharged from the leaky boundaries. It should be noted that these statistics can be reversed depending on the specified period. The difference between the input and output pollution values in the study area indicates a net accumulation of 8192 units. To analyze the sensitivity of contamination dispersion in the porous aquifer environment and the variations in coastal drainage patterns obtained from the finite difference simulation, the explicit and implicit methods, as well as the random walk particle tracking method, were investigated in a portion of the basin area using the South Side Implicit method. One of the main objectives of this sensitivity analysis is to evaluate the results of the uncalibrated qualitative model and examine the particle dispersion in the adjacent area of the contaminated landfill region to assess the error of the proposed model by developing a limited test. The calculated error or computational difference between the explicit and implicit methods and the applet model is considered negligible. For example, the calculated error between the explicit and backward methods and the applet model ranges from 0.086 to 0.372 units for a concentration interval of 0.512 units and 0.680 units for a time interval 0.537. Therefore, the computational differences are not significant. Furthermore, based on theoretical sensitivity analysis of contamination dispersion, the laboratory model demonstrates that the flow direction in this modeling is from west to east, as expected. [ABSTRACT FROM AUTHOR]

This paper investigates the optimal remediation process in an aquifer using Modflow 6 software and genetic algorithms. A theoretical confined aquifer has been polluted over a long period of time by unnoticed leakage in a pipeline conveying leachate from an adjacent landfill to a wastewater treatment plant. When the extended leakage and groundwater pollution are discovered, the optimal planning of the remediation strategy is investigated using the pump-and-treat method or/and hydrodynamic control of the pollution. The practical goal is to find the optimal locations and flow rates of two additional pumping wells, which will pump the polluted water or/and control pollution, protecting an existing drinking water pumping well, securing its fully operational mode even during the remediation process with the minimum possible cost, simply represented by the pumped water volume of the additional wells. The remediation process is considered complete when the maximum concentration in the aquifer drops below a certain limit. The Modflow software (handled by the Flopy Python package) simulates the flow field and advective–dispersive mass transport, and a genetic algorithm is used as the optimization tool. The coupled simulation–optimization model, Modflow-GA, complemented by a sophisticated post-processing results analysis, provides optimal and alternate sub-optimal remediation strategies for the decision makers to select from. [ABSTRACT FROM AUTHOR]

Background and Objectives: Due to limitations in renewable freshwater resources, proper management of resources and demands is one of the key factors for achieving sustainable management. This is a critical factor in achieving sustainable water management. This study aims to investigate the impact of government contractionary policies on the reduction of surface and groundwater rights in the Miandoab plain and quantitatively examining their impacts on groundwater resources. Materials and Methods: The quantitative modeling of groundwater in the Miandoab plain utilized data from 120 observation wells. Geological, soil layer, and recharge layers pertinent to the region were collected. Groundwater level changes from October 2010 to September 2016 were modeled and analyzed in both stable and unstable transient states using the MODFLOW code. The model calibration stages were performed based on adjusting the hydrodynamic parameters of the aquifer, such as hydraulic conductivity and recharge, for 50 time steps from November 2010 (70% of the modeling period). The best fit between computational and observational values was achieved both manually and automatically. 30% of the data was used for model validation. The model's sensitivity to the aquifer's hydrodynamic coefficients was examined. Finally, various scenarios related to water allocation reduction policies of the region and their effects on groundwater behavior, such as reducing extraction and recharge by decreasing surface water entering the plain, were quantified. Results: The results demonstrated that the Root Mean Square Error (RMSE) was approximately 1 and 1.68 meters for the stable and unstable (transient) states, respectively. The hydraulic conductivity values within the aquifer ranged between 3.5 and 28 meters per day, and the specific yield values varied between 3 to 24 percent. The model exhibited the highest sensitivity to surface recharge and the least sensitivity to specific yield. The Pearson coefficient for the calibration and validation period of the unstable state exceeded 0.98, indicating a high degree of model accuracy. All effects of the government's contractionary policies on reducing 40% of surface water and balancing the aquifer with the levels of natural aquifer recharge were implemented. Given that the average drop in groundwater level is approximately 0.1 meters per year, a scenario of reducing extraction from all operating wells has been applied to balance the aquifer. With a 5% reduction in extraction, the aquifer is projected to experience a half-meter increase in the static level. The Miandoab aquifer, due to the low slope of the plain, is sensitive and shows a part of the plain as a water ponding in reducing extraction at a high rate, hence any policymaking should be based on modeling. Conclusion: To improve the conditions of the Miandoab aquifer, one of the country's most unique aquifers, suggestions have been made for changes in the cultivation pattern of agricultural products, monitoring of water extraction from operating wells, and examination of the impact of climate change and drought on groundwater resources in terms of quantity and quality. Various scenarios, including optimization and change of cultivation pattern, as well as the construction of drainage in areas where evaporation from the aquifer is high, should be evaluated to improve the aquifer situation. [ABSTRACT FROM AUTHOR]

The severe shortage of water resources is the most important cause of the uncontrolled abstraction of groundwater resources in semi-arid regions. In this regard, modeling and forecasting groundwater levels can help in the accurate estimation of watershed water consumption and sustainable agricultural development. In the present study, the interaction effect of surface and groundwater using SWAT, WEAP, and MODFLOW models on agricultural water consumption of Kavar plain in Fars province has been evaluated. Also, the simultaneous impact of climate change, increasing the efficiency of irrigation systems, and changing the cultivation pattern to predict the groundwater level in the future were analyzed. For these purposes, first, the changes in crop pattern and type of irrigation systems during the decade 2008 to 2018 were investigated; then different management scenarios were defined to balance the groundwater level. The results of predicting climatic parameters indicate that in all three scenarios of emissions in the next period (2021–2040), the temperature will increase (0.54–1.01 °C) and precipitation will decrease (3–10%). The combination of SWAT and WEAP models with the MODFLOW model showed that by using these models, the interaction behavior of surface water and groundwater, the amount of recharges, and groundwater level can be quantitatively simulated. Also, applying different irrigation scenarios in the models showed that by adjusting the cultivation pattern and improving surface and pressurized irrigation efficiencies, the amount of groundwater abstraction in dry and normal conditions can be reduced by 23 to 42 percent. Therefore, the groundwater level will increase in the next period. [ABSTRACT FROM AUTHOR]

The paper investigates the mechanism of seawater intrusion and the performance of free and open-source codes for the simulation of variable density flow problems in coastal aquifers. For this purpose, the research focused on the Marathon Watershed, located in the northeastern tip of Attica, Greece. For the simulation of the groundwater system, MODFLOW, MT3DMS and SEAWAT codes were implemented, while sensitivity analysis and calibration processes were carried out with UCODE. Hydraulic head calibration was performed on the MODFLOW model, and TDS concentration was validated in the SEAWAT model. The calibrated parameters of the MODFLOW model were obtained for the variable density flow simulation with SEAWAT. The MODFLOW and SEAWAT hydraulic head outputs were analyzed and compared to one another. The outcome of this analysis is that SEAWAT produced slightly better results in terms of the hydraulic heads, concluding that parameter transferability can take place between the two models. For the purpose of the seawater intrusion assessment, the use of the SEAWAT code revealed that the aquifer is subjected to passive and passive–active seawater intrusion during wet and dry seasons, respectively. Finally, an irregular shape of a saltwater wedge is developed at a specific area associated with the hydraulic parameters of the aquifer. [ABSTRACT FROM AUTHOR]

Inverse problems in hydrogeology pose a great challenge for modelers as they are ill-posed, resulting in a non-unique solution. High computational resources are needed for the calibration process, especially in the case of highly parameterized aquifers like karst limestone, characterized by significant heterogeneity. The null-space Monte Carlo (NSMC) is a parameter-constrained Monte Carlo approach that can be used to quantify uncertainty, as it produces a set of solutions that calibrate the model. This method is used to assess uncertainty in the calibration of a karst aquifer in Qatar, which has high heterogeneity. Pilot points were used to reflect the geostatistics of the calibrated field, and the calibration results at these points were interpolated over the aquifer area using kriging. The NSMC was then used to produce 200 realizations of the null-space parameter field using the constrained random variable of hydraulic conductivity. The null-space realizations were then incorporated into the parameter space derived from the calibrated model. Statistical analysis of the calibrated hydraulic conductivity revealed a variation ranging from 0.1 to 350 m/d, indicating a considerable variability in the aquifer’s hydraulic parameters. The areas with high hydraulic conductivity were concentrated in the central and eastern parts of the aquifer, and these same areas exhibited a high standard deviation. Based on the findings of this study, while the NSMC method is effective for uncertainty analysis in solving inverse problems, it is important to note that a considerable number of runs are necessary to reach the threshold of calibration error. This is because of the significant non-linearity inherent in the karst aquifer.

The deposits of mine tailings can be a source of groundwater contamination by metals. In this study, we simulated the concentrations of iron, manganese and aluminum in groundwater potentially affected by drainage from tailings deposits located in Brumadinho (Brazil). The aim was to verify whether the concentrations observed in the region can be attributed to these drainages. The simulation used the FREEWAT graphical interface, which incorporates the MODFLOW model, the hydraulic properties of existing unconfined and confined aquifers, the spatial distribution of the tailings’ deposits, and the dissolved iron concentrations measured in drilled wells. The simulation period was 20 years, starting in 2019 after the collapse of B1 tailings dam of Córrego do Feijão mine of Vale, S.A. The modeling results revealed plumes of metal contamination progressively less dispersed over time, in the unconfined aquifer, and increased metal concentrations in the confined aquifer. The simulated concentrations in both aquifers were generally lower than the legal limits imposed for human consumption, although some areas in the vicinity of the deposits had iron and manganese concentrations higher than those limits, especially in the unconfined aquifer, and these areas widened over time. The most relevant result was the revelation that the contribution of tailings drainage to the iron concentrations observed in the drilled wells might have not exceeded 1%. This is important from a management standpoint, because monitoring of anthropogenic groundwater contamination in these cases (where rock weathering dominates groundwater chemistry) becomes more challenging.

The sustainable management of groundwater resources in developing countries is often challenging due to limited measurement and monitoring infrastructure to collect data necessary for decision support. To make a contribution towards addressing these challenges, this study investigated the use of Internet of Things (IoT) technology and low-cost sensors to collect the required groundwater-level data and develop a model to map the recharge potential with stormwater. The study focused on two stormwater ponds located in a highly urbanised area in Cape Town, South Africa. A combination of Geographic Information System and analytic hierarchy process was integrated to generate a groundwater recharge potential zone map of the study area. The IoT-based data were used to develop and calibrate a numerical groundwater model in MODFLOW. The study determined that retrofitted stormwater ponds are potential groundwater augmentation zones and can provide opportunity for stormwater recharge in urban areas. Overall, this study highlights the potential of IoT to collect hydrogeological data with low-cost sensors. Data can be collected at high temporal resolution, and the spatial scale can be increased due to availability of low-cost sensors. HIGHLIGHTS Internet of Things (IoT)-based data were leveraged to address challenges in groundwater management.; Rapid battery drain powering the IoT system was mitigated by reducing the data collection frequency and dead sleep mechanisms.; Geographic Information System–based analysis and analytic hierarchy process were employed to map the recharge potential in a highly urbanised area in Cape Town.; This study demonstrated that stormwater ponds have the potential to recharge groundwater aquifers through infiltration.;

The threat to groundwater by toxic wastewater in the vicinity of cassava processing mills has not been taken seriously in the Niger delta region. Consequently, the fate of cyanide from the surficial surface into underlying aquifers was modelled by MODFLOW and MT3DMS. The vulnerability is influenced by subsurface geology, vertical hydraulic conductivity and sorptive characteristics of the unsaturated zones, seasonal recharge and depth to water levels. The migration of cyanide is considerably not different from the direction of groundwater flow. Its migration is significantly affected by the geology and constituents of the unsaturated zones which retard the spread of cyanide plume into the underlying aquifers. The study has successfully demonstrated the effectiveness of MODFLOW and MT3DMS in determining the vulnerability of aquifers to cassava wastewater from processing mills and associated contaminants. The pumped-and- treat technique is specifically suggested for the remediation of cyanide contaminated aquifers characterized by high hydraulic conductivity.

The accessibility and deployment of complex hydrological models remain significant challenges in water resource management and research. This study presents a comprehensive workflow for converting Python-based hydrological models into web APIs, addressing the need for more accessible and interoperable modeling tools. The workflow leverages modern web technologies and containerization to streamline the deployment process. The workflow was applied to three distinct models: a GRACE downscaling model, a synthetic time series generator, and a MODFLOW groundwater model. The implementation process for each model was completed in approximately 15 min with a reliable internet connection, demonstrating the efficiency of the approach. The resulting APIs provide standardized interfaces for model execution, progress tracking, and result retrieval, facilitating integration with various applications. This workflow significantly reduces barriers to model deployment and usage, potentially broadening the user base for sophisticated hydrological tools. The approach aligns hydrological modeling with contemporary software development practices, opening new avenues for collaboration and innovation. While challenges such as performance scaling and security considerations remain, this work provides a blueprint for making complex hydrological models more accessible and operational, paving the way for enhanced research and practical applications in hydrology.

This paper focuses on deriving new approximate analytical solutions in wedge‐shaped aquifers. The proposed methodology is applicable to any type of aquifer namely, leaky, confined and unconfined, under both steady state and transient flow conditions. By applying the method of images and separating the flow field into sections using physical arguments, approximate analytical expressions are obtained for the drawdown function, which in contrast to the conventional theory, are applicable to any arbitrary wedge angle. Moreover, the solutions fully observe the boundary conditions, while they preserve the continuity of the drawdown, which can be calculated directly at any point of the flow field. Nevertheless, comparison of the results of the new approximate analytical solutions to numerical ones, has been considered necessary to check their validity. MODFLOW, a well‐known numerical tool is used to calculate the numerical results. The discrepancies between the numerical results and those of the approximate analytical solution are negligible. The main advantages of the proposed methodology are the following: (a) The model needs only finite number of terms compared to conventional analytical and numerical solutions that involve infinite series, (b) The computational load is low, so it can be easily used in conjunction with meta‐heuristic algorithms to solve groundwater resources optimization problems, (c) Stream depletion rate can be calculated rather accurately and (d) The method is applicable to related flow problems. Key Points: New functions for drawdown calculation in wedge‐shaped aquifers are presentedThe proposed functions are suitable to be used in conjuction with meta‐heuristic algorithms to solve groundwater optimization problemsConvergence of the results obtained from the set of functions and numerical methods (MODFLOW) point out the validity of the proposed solutions [ABSTRACT FROM AUTHOR]

Considering the different quantitative and qualitative issues of groundwater resources, which are caused by population growth and development, the implementation of comprehensive plans and taking management measures in order to protect and restore groundwater resources are highly recommended. In this regard, the evaluations of various management measures are necessary because based on the results, it is possible to make appropriate decisions about how to control water consumption as the main part of future policies. Hashtgerd study area is located in Alborz province in Iran and requires appropriate decisions regarding how to control the intensive groundwater resources depletion and quality reduction. An average storage deficit of 4.08 million cubic meters per year was realized during 2012–2016 and water quality decreased. The present study has investigated the quantitative and qualitative changes of groundwater resources using MODFLOW and MT3DMS in response to different management schemes. Different management schemes based on a national plan called "the aquifer restoration plan" were applied for the 20-year horizon (2016–2036). It was found that by blocking unlicensed agricultural wells and modifying the licenses for licensed agricultural wells in the entire aquifer area, the storage would increase by an average of 7.23 million cubic meters per year, and nitrate and sulfate concentrations would decrease by 0.06 and 1.14 mg/l per year, respectively. Artificial recharge of the aquifer with treated wastewater was found to have a great impact on reducing pollutants and improving the water quality, though it had no desirable effect on the groundwater level. In this case, nitrate and sulfate concentrations decrease by 0.53 and 2.24 mg/l per year, respectively. [ABSTRACT FROM AUTHOR]

Dam removal is becoming more common as aging infrastructure deteriorates and people seek to restore the environmental conditions created by dams. Despite this growth in dam removals, studies analyzing effects of dam removal on meadow ecosystems are limited. Groundwater is an important and often overlooked component of hydrologic systems, particularly in the case of surface water manipulation like dam removal. A planned dam removal project at Van Norden Meadow, in the California Sierra Nevada Range at Donner Pass, was selected to quantify the impact of dam removal on shallow groundwater and the associated meadow system. Mountain meadows are inseparable from local hydrology and are a valuable resource in California's Sierra Nevada range, providing an important source of water, supporting natural biotic communities, and serving as climate change refugia. Using MODFLOW, an open-source finite-difference groundwater modeling program, we established a baseline groundwater model for Van Norden Meadow and used it to assess potential impacts of dam removal on the subsurface water balance in relation to hydrologic niches to support plant communities. The model predicted a slight decrease of less than 0.9 m in the water table of the lower meadow below a recessional moraine, but no impact to the water table in the upper meadow. The areas adjacent to the dam along the reservoir footprint were found to be most at risk of losing wet meadow vegetation. The model also suggested dam removal led to a 3% increase in baseflow drainage below the meadow. This increase was balanced by an 8% decrease in evapotranspiration and a slight increase (0.9%) in the mobilization of stored groundwater. While no further actions following removal may be needed in the upper meadow, restoration activities, such as vegetation planting or channel filling, may be needed to offset the decrease in the water table and promote wet meadow habitats in some regions of the lower meadow. However, newly exposed areas in the reservoir footprint will promote hydric vegetation recruitment, suggesting a potential net increase in wet meadow vegetation after dam removal in Van Norden Meadow. More broadly, we found MODFLOW was suitable for modeling dam removal despite challenges with steep slopes and thin conductive layers over bedrock. [ABSTRACT FROM AUTHOR]

Focusing on the Lower Bari Doab Canal (LBDC) command area, characterized by its heavy reliance on agriculture, this study addresses the critical issue of groundwater table fluctuations in response to diverse pumping scenarios. Herein, we comprehensively evaluated the dynamic interplay between crop water requirements and groundwater pumping within the expansive canvas of the LBDC, which is facing water shortages. Using the Penman–Monteith equation, we calculated annual average evapotranspiration for major crops—wheat, maize, cotton, rice, and sugarcane. Three-dimensional MODFLOW-based numerical modeling was used to analyze the dynamics of groundwater regimes. MODFLOW was calibrated from 2010 to 2020. Thereafter, we simulated water table changes under a 20% increase and decrease in groundwater extraction up to 2040s. Results revealed significant variations in water demands among these crops, with sugarcane requiring the highest average annual evapotranspiration at 1281 mm. Spatiotemporal analysis revealed substantial declines in the water table in the tail-end command areas, particularly Sahiwal and Khanewal where the decline was 0.55 m/year between 2010 and 2020. The upper reaches, such as Balloki and Okara, experienced milder declines. In considering management scenarios, a 20% increase in groundwater extraction up to September 2040 was projected to raise pumping to 4650 MCM/year. and decrease the net water balance to −235 MCM/year. Alternatively, a 20% decrease in groundwater extraction up to September 2040 could reduce pumping to 4125 MCM/year and increase the net water balance to 291 MCM/year. This study sheds light on major crop water requirements, spatiotemporal groundwater dynamics, and the implications of groundwater extraction in the LBDC command area. Scenarios presented here, encompassing increased and decreased groundwater extraction, offer invaluable guidance for policymakers and stakeholders seeking a balance between agricultural productivity and long-term groundwater sustainability. [ABSTRACT FROM AUTHOR]

In this study, the accuracy of estimating shallow aquifer recharge values in AstaneKouchsefahan using two models: SWAT (a surface water hydrological model) and MODFLOW (a groundwater flow model) was evaluated. Then the need for using SWAT in the modeling of groundwater flow, which is typically done by MODFLOW, was evaluated. For this purpose, the simulation of the Astane-Kouchsefahan aquifer was done by MODFLOW using GMS graphical user interface. Then the SWAT model was built for the AstaneKochsefahan watershed and calibrated by the SUFI2 algorithm in SWAT-CUP software. In the following, after determining the two models' common spatial and temporal range, the aquifer recharge amounts were compared according to the outputs of the two models. MODFLOW results showed that the total aquifer recharges including recharge from the river in 1391-1392 were equal to 102.71 and 23.71 million m3, respectively. The highest and the lowest amounts of aquifer recharge occurred in December and April, respectively. The results of SWAT showed that the amounts of aquifer recharges including recharge from the river are estimated to be 138.34 and 35.09 million m3, respectively. So, the highest and the lowest recharge amount occurred in December and September, respectively. Based on the regional circumstances, SWAT offers more dependable estimates of the groundwater recharge parameters by considering surface water parameters and factors like the influence of dams and water transfer channels, soil characteristics, land use, climatic and meteorological data, and information regarding agriculture and irrigation management. Consequently, integrating the precise recharge results from SWAT into groundwater models such as MODFLOW leads to enhance and more reliable evaluations of the aquifer's state. [ABSTRACT FROM AUTHOR]

This study investigated the interaction of groundwater flow and foundation piles located in the vicinity of the Danube River. The piles represent an obstacle to the groundwater flow, causing a backwater effect upstream whilst increasing the local flow velocity. On the other hand, a high flow velocity around the piles can cause suffusion of the surrounding soil in the long term, thus significantly reducing the shaft resistance of the piles. A 3D model of groundwater flow and its impact on the piles was developed in the software 10.3 package GMS based on MODFLOW 2005. The model was calibrated by comparing the calculated results with the measured values in the control well for different values of the filtration coefficients. In the calibration process, foundation piles were not applied in the model. After the calibration process, the piles were implemented into the model and the underground flow was simulated in the study area for the calibrated year 2006. The impact analysis was carried out by comparing the groundwater level change over time in the pile zone at three control points, in cases with and without the piles, along with the flow net analysis at the piles' location. The results indicate no influence of the piles on the groundwater flow in the study area, both in terms of critical flow velocities and a possible backwater effect upstream. [ABSTRACT FROM AUTHOR]

Horizontal drains (HDs) are commonly deployed at open pit mines to depressurize the pit walls and thereby improve pit wall stability. If successful, depressurization maintains current pit wall angles and improves stripping ratios, which directly influences mine economics. HDs are commonly designed using empirical approaches that have been developed based on experience at other mines and are often aided by 2D and 3D analysis using groundwater models at sites with complex geological and structural settings. Specialized techniques for simulating HDs in these models became available nearly 20 years ago with the introduction of discrete feature elements in FEFLOW, a proprietary groundwater modelling package. More recently, introduction of unstructured grids allowed direct representation of HDs and their sequencing in MODFLOW, a publicly available modelling package that is widely used at mine sites. This paper provides an example of how HD design can be aided by 3D numerical analysis that utilizes these new MODFLOW simulation capabilities. [ABSTRACT FROM AUTHOR]

The shallow, Memphis, and Fort Pillow aquifers are the three major water‐bearing strata beneath Memphis, Tennessee, where the Memphis aquifer serves as the primary groundwater source. The upper Claiborne confining unit (UCCU) separates shallow and Memphis aquifers across the majority of Shelby County, acting as an upper protective layer for the Memphis aquifer. However, hydrogeologic breaches within the UCCU create a hydraulic connection and provide an avenue for potential contaminant migration from the shallow to the Memphis aquifer. This research aims to minimize contaminant migration, mitigate risks, extend existing wells' life that may face water contamination, and find suitable locations for future well construction. Several strategies are developed addressing well depth, seasonal well operation, and mapping no‐drilling or red zones to provide practical solutions. A numerical groundwater modeling technique is developed for each strategy that includes stochastic simulation–optimization and customized simulation models depending on the strategy. The models result in thousands of numerical simulations for each scenario to identify recurring patterns of contaminant movement to and through the Memphis aquifer. The results indicate that optimum well positions (spatially and vertically) and modification to pumping can increase the life expectancy of wellfields, offer sustainable management of the Memphis aquifer, and reduce contaminant migration through 2050. [ABSTRACT FROM AUTHOR]

The fate of agriculture in Pakistan is predominantly concerned with excessive water mining threats to the subsurface water resources. The current study integrates the Visual MODFLOW-2000 application to estimate the water balance of an aquifer bounded by the Chenab River in the West and the Ravi River in the East, which covers an area of about 2.98 million hectares. An assimilated method of groundwater flow is employed to characterize the flow dynamics of the Rechna Doab aquifer. The Digital Elevation Model (DEM) produced by the Shuttle Radar Topography Mission (SRTM) and a mesh of discretized cell size (2500 m) were incorporated into the model design. The conceptual model of the alluvial aquifer involves trifold vertical boundaries (an initial fold thickness set up to 150 m). The model input parameters are precipitation, seepage through irrigation, return flow, recharge, hydraulic conductivity and evapotranspiration. Empirical relations are established (at the basin scale) for the discharge input of irrigation canals. Model results confirm that groundwater flow follows the topographic configuration of the study area (i.e., northeast to southwest), and the seepage from irrigating canals and rainfall appeared to be the main source of groundwater recharge among various resources. The zone budget study under steady state simulation showed that the total direct recharge to the aquifer is calculated as 522,910 acre foot. The simulated water balance of the studied aquifer reflects more fluctuations in river leakage. The predictive optimized model reflects an adaptation of canal lining and installation of additional tube wells that will minimize canal seepage by 70% and lead to the reclamation of 37,000 acres of water-logged land for normal cropping. [ABSTRACT FROM AUTHOR]

The multi-aquifer system of the Nubian aquifer in central Sudan hydrogeological system was simulated using a three-dimensional steady-state model. The goal of the study is to detect the effect of pumping on the groundwater flow and thus, the aquifer productivity. The conceptual model of the study area was built based on the available geological and hydrogeological data guided by geophysical survey. Processing MODFLOW numerical code was used to calculate the hydraulic head and water balance under the existing boundary conditions. The model accurately simulated the hydraulic head with a determination coefficient of 0.88. The calibrated model indicated that the change in storage is 0.56 m3/day indicating the study area constitutes highly productive zone and is recommended for groundwater developments. [ABSTRACT FROM AUTHOR]

A new software HMSE has been developed to facilitate external coupling between two well-known programs for subsurface flow modeling: MODFLOW-2005 (saturated zone flow) and HYDRUS-1D (unsaturated zone flow). Two coupling schemes have been implemented. In the first case the groundwater recharge flux is calculated by HYDRUS-1D assuming a fixed water table position and then passed to MODFLOW input files. In the second case the water table position in HYDRUS-1D is updated periodically using the solution from MODFLOW. HMSE can be deployed in 3 modes: local, Docker and Kubernetes cluster. A web-based interface is provided to configure and run the simulation in all three cases. The software is applied to simulate groundwater table fluctuations observed in a shallow aquifer during three years.

Water management in snowmelt hydrologic regimes, characterized by large annual fluctuations in stream flow driven by seasonal snow melt, faces the challenge of highly variable supply that often does not align with timing of demand. Climate change may exacerbate management challenges by significantly reducing snowpack or shifting snow melt earlier. Here, managed aquifer recharge (MAR) is evaluated as a potential strategy to reallocate excess early-season stream flow to time periods when less surface water is available. This strategy differs from traditional MAR, where the goal is to minimize loss to surface water. We assess how to site MAR operations such that groundwater recharge flows back to the surface water system in a lagged manor to benefit water management objectives, which we term “enhanced baseflow.” We use a regional groundwater model for the Treasure Valley aquifer located in southwestern Idaho, United States to demonstrate a generalizable approach using regional groundwater models as tools to identify favorable baseflow enhancement locations. Hypothetical MAR is simulated at 197 candidate locations, which are then evaluated for how effectively they meet potential management objectives. In addition to demonstrating the modeling and evaluation approach, we discuss lessons learned from applying a pre-existing regional groundwater model to MAR for enhanced baseflow and also describe important considerations, such as the physical and institutional availability of surface flows and specific management objectives, when assessing regional and site-specific suitability of MAR for enhanced baseflow as a potential management strategy.

Abstract Aquifer systems, because of the presence of frequently complex geological structures, may extend beyond watersheds limits. Interbasin groundwater flow is often identified among watersheds. Because geological systems are complex ones, modelling tools are needed for its estimation. In this paper, we quantify the outflows from the endhoreic Gallocanta watershed (Spain) by means of a MODFLOW numerical model in order to assess the robustness of the boundaries of the Gallocanta Groundwater Body. Our results show the Gallocanta watershed is hydrogeologically connected with the adjoining Piedra-Ortiz and Jiloca watersheds (discharging annually in these basins about 4 and 1 Mm3 respectively). Furthermore, we hypothesized the presence of geological features altering the groundwater flow. Additional simulations were run to analyse the changes in the water budget in the cases of: i) groundwater pumping no longer allowed by the authorities, and ii) a potential drought scenario. In the first case, the results forecast an increase in discharge to the Piedra-Ortiz and Jiloca watersheds, while in the second case a diminution of the outflows to the two neighboring basins is foreseen. We then propose a larger and unique groundwater body, spanning from the Caminreal Springs on the east and the Piedra-Ortiz basin on the west, including a moving groundwater divide internal to the Gallocanta watershed. Monitoring the baseflow of the Piedra-Ortiz river and of the Caminreal Springs will allow to get information on the evolution of the groundwater resource availability in the Gallocanta watershed. Our results stress the importance of conjunctively using data and traditional geologic knowledge (i.e. surface geology maps) along with numerical modelling analyses. This holds especially true in areas, such those of hard-rock aquifers, where scarce hydrogeologic data are available, to test conceptual models, to derive and to infer information on water budgets and on the presence of relevant structural features driving the groundwater flow. This approach may lead to informed decision-making on groundwater body boundaries definition for the application of relevant groundwater management regulations.

Groundwater, essential for supplying drinking water to half of the global population and supporting nearly half of all irrigation needs, faces significant contamination risks. These risks pose serious threats to human health and ecosystem integrity, driven by increasing pressures from both concentrated and diffuse pollution sources, as well as from growing exploitation. The presented research was conducted with the dual objectives of identifying sources of nitrate contamination (up to 128.1 mg/L) in an oxic groundwater source (Perkićevo, Serbia) and proposing an optimal extraction regimen to ensure a sufficient supply of potable water. Correlations between chemical elements’ concentrations and principal component analysis (PCA) indicated a significant relationship between anthropogenic impact indicators (NO3−, Na+, B, Cl−, SO42−, KMnO4 consumption, and electroconductivity), unambiguously showing that groundwater quality was primarily impacted by untreated sewage inflow and confirming nitrate’s tracer behavior in oxic environments. The spatial distribution of selected parameter concentration gradients highlighted the expansion and distribution of the contamination front. A numerical groundwater flow model (Vistas 4 and Modflow) was applied to determine the groundwater flow direction and the quantity of groundwater originating from different parts of the investigated area. Through four simulated groundwater extraction scenarios, Scenario 2, with an average extraction rate of 80 L/s from 12 wells, and Scenario 3, with an average extraction rate of 75 L/s and 4 additional wells, were identified as the most optimal, providing a sufficient quantity of adequately sanitary water.

Simulating shallow groundwater (SGW) flow dynamics and stream–SGW interactions using numerical modeling tools is necessary to develop a mechanistic understanding of water flow systems and improve confidence in water resource management practices. A three-dimensional (3D) SGW flow model was developed for a riparian wetland in a mixed forest and agricultural catchment in West Virginia (WV), Appalachia, USA, using a Modular 3D Groundwater Model (MODFLOW). The MODFLOW simulation was calibrated in steady (R2 = 0.98, ME = −0.21, and RMSE = 0.77), transient state (R2 = 0.97, ME = −0.41, and RMSE = 1.28) and validated (R2 = 0.97, ME = −0.28, and RMSE = 1.05) using observed SGW levels from thirteen nested piezometers under steady and transient states. An experimental MT3D transport scenario was developed to show the lateral transport of NO₃-N from the aquifer to stream cells. Relatively stable SGW head distribution was observed. In the downstream reach, SGW discharge varied from 948 m3/day to 907 m3/day in 2020, with creek seepage ranging from 802 m3/day to 790 m3/day. Similarly, SGW input to the stream ranged from 891 m3/day to 978 m3/day, while creek seepage ranged from 796 m3/day to 800 m3/day in 2021. In upstream reaches, losing stream conditions were observed in January, June, and September 2020 and January to April 2021, while gaining stream conditions prevailed during other months. Thus, an approximately monthly alternating gaining–losing stream condition was observed in the upstream area. An experimental MT3D transport scenario resulted in an advection–dispersion scenario, showing a cumulative loss of 947 g of NO3-N from SGW to the stream. Denitrification accounted for the cumulative loss of 1406 g of NO3-N from SGW, surpassing 639 g of nitrate from the SGW to the stream during the study period. Additionally, particle tracking using MODPATH indicated a long residence time for SGW nutrients, affirming the efficiency of nitrogen transformation through denitrification. This study is among the first to simulate hydrologic and nutrient interactions in riparian wetlands of a mixed land use catchment in the Appalachian region of the northeastern United States. The results better inform water resource management decisions and modeling efforts in the Appalachian region and similar physiographic regions globally.