Three-dimensional Groundwater Flow Research Articles

Simulation and prediction of land subsidence in Decheng District under the constraint of InSAR deformation information

Land subsidence, marked by a decline in surface elevation, poses a significant threat to urban infrastructure and safety. Accurate subsidence information and a reliable prediction model are crucial for prevention and control. In this study, we used persistent scatterer interferometric synthetic aperture radar (PS-InSAR) technology to obtain long-term land subsidence data and analyzed subsidence characteristics in Decheng District. By integrating hydrogeological and groundwater data, we developed a three-dimensional groundwater flow and one-dimensional compaction model through numerical simulation. Furthermore, the subsidence data monitored by PS-InSAR were used to further constrain and validate the model. The evolution trend of land subsidence under different groundwater exploitation scenarios was predicted and analyzed. The results showed that from May 2017 to December 2021, the cumulative maximum subsidence in Decheng District reached −173 mm. The subsidence area is mainly concentrated in the northern area, and its subsidence center is near Qiaoyuan Town. According to the Land Subsidence Prevention and Control Plan of Dezhou City, Shandong Province (2018–2025), we set up different groundwater mining scenarios with the goal that the rate of land subsidence in the key prevention and control area is less than 35 mm/yr in 2025.The Fluid-solid coupled model prediction analysis results indicated that a 30% reduction in groundwater exploitation is reasonable.

Developing three-dimensional groundwater flow modeling for the Erbil Basin using Groundwater Modeling System (GMS)

Developing three-dimensional groundwater flow modeling for the Erbil Basin using Groundwater Modeling System (GMS)

Numerical Study on the Influence of Aquitard Layer Distribution and Permeability Parameters on Foundation Pit Dewatering

Evaluating the influence of geologic features on dewatering efficiency, particularly within strata of varying permeability, is critical to optimizing dewatering designs for deep excavations. In river valley areas, river sedimentation results in a discontinuous distribution of relatively aquitard layers (clay layers). The evaluation and calculation of the distribution and permeability parameters for foundation pit dewatering are very important when on-site geological data are insufficient. For this purpose, the deep excavation pit on the right bank and floodplain of Chongjiang River is taken as an example in this article. A three-dimensional groundwater flow model was constructed using the Unstructured Grid (MODFLOW-USG) software package version 1. The model was carefully calibrated using hydrogeologic features and observed groundwater levels to ensure its reliability. The simulation results effectively reproduce actual dewatering processes. The study reveals the following findings: (1) Increased aquitard layers (clay layer) enhance the barrier effect, thereby improving dewatering efficiency. (2) Increased clay layer permeability and storage coefficients reduce dewatering efficiency, while the specific yield of the clay layer has less pronounced effects. (3) Due to the discontinuous nature of the clay layer, dewatering rates are higher when the clay layer is below the riverbed than when it is in the flow boundary area (foothills).

Transport of pollutants in groundwater of domestic waste landfills in karst regions and its engineering control technologies

Domestic waste produces leachate with a high concentration of pollutants in the landfill process due to biochemical degradation stages like compaction and fermentation. A large number of cases show that anti-seepage membranes widely used in refuse landfills tend to rupture under long-term tension and corrosion, causing leachate to enter the groundwater system and pollute the environment. To reveal the phenomenon of groundwater contamination in refuse landfills, typical domestic waste landfills in karst regions were examined, on the basis of a summary of hydrogeological conditions and hydrochemical characteristics, a three-dimensional groundwater flow model and solute transport model were constructed to analyze the pattern of pollutant diffusion, and its controlling factors, under the current conditions and massive rupture of anti-seepage membrane. The results show that with a minor rupture of the anti-seepage membrane, the area of the low pollution region increases first and then decreases while that of the slight pollution region continuously increases; When a massive rupture of the anti-seepage membrane appears, the ranges of heavy pollution region and total pollution regions continue to grow; Pollutant migrates along the same direction as the groundwater flow and diffuse from high concentration region to low concentration regions under the differential concentration effect. Based on the temporal-spatial distribution characteristics of groundwater pollutants, two engineering control schemes, namely, curtain grouting blocking and group well pumping, were established. A comparison of the two control schemes shows that group well pumping stably maintains water quality safety over the long term, pollutants overflow from both sides of the curtain after they have accumulated to a certain point of concentration, causing damage to the groundwater environment in the conservation area.

MODFLOW/MT3D Based Three-Dimensional Groundwater Flow and Transport Simulation of Uranium Contamination in Bathinda District, Punjab, India

MODFLOW/MT3D Based Three-Dimensional Groundwater Flow and Transport Simulation of Uranium Contamination in Bathinda District, Punjab, India

Efficient representation of transient tidal overheight in a coastal groundwater flow model using a phase-averaged tidal boundary condition

Ocean tides cause water table overheight near the seaward boundary of coastal aquifers which can have a large impact on groundwater flows and saltwater intrusion. Despite this, regional-scale coastal groundwater flow models often neglect the effects of ocean tides or alternatively assume that the influences of ocean tides and sea level are constant over time. These simplifications are often required because simulation of the phase-resolved tidal signal at a coastal boundary is computationally demanding. Our objective was to derive a phase-averaged tidal boundary condition for application along gently sloping coastlines that enables simulation of real, complex tidal signals combined with sea-level changes due to meteorological effects. The boundary condition extends an existing analytical solution of tidal overheight by including an empirical correction function for conditions where the assumptions of the existing solution are violated. The correction function was developed by conducting a parametric study on an idealized two-dimensional cross-sectional coastal aquifer model and considering the effects of parameters including horizontal hydraulic conductivity, vertical anisotropy, specific yield, aquifer thickness, and beach slope. The performance of the new phase-averaged tidal boundary condition was assessed using a three-dimensional groundwater flow model of the island of Spiekeroog, Northwest Germany, which comprises complex coastal morphology with non-planar beach slopes. Simulations applying the new boundary condition were compared to simulations that adopted a phase-resolved tidal boundary condition and to observed groundwater levels. Accounting for time-varying changes in the tidal signal and sea level was found to be critical to simulate observed data and to adequately reproduce the transient tidal overheight simulated by the phase-resolved model. The performance of the new phase-averaged boundary condition in the regional-scale model varied depending on how the coastal morphology was represented in the boundary condition with local morphological features increasingly important for lower intertidal vertical infiltration capacity (low isotropic hydraulic conductivity or high vertical anisotropy) or specific yield. In conclusion, the new boundary condition presented overcomes current limitations in simulating transient tidal overheight in regional-scale groundwater models.

Groundwater Flow Modeling of A Microwatershed using Visual Modflow Flex

The present study attempts to make a simulation of groundwater flow modeling in Chikkodi micro-watershed Belagavi (District), Karnataka. A two-layer conceptualization and the three-dimensional groundwater flow model are primarily underlain by weathered basalt and fractured basalt. The first layer weathered zone is 30m from the ground surface and the second layer fractured zone is 80m below the ground surface spread over 20 rows and 20 columns. The cell height is 674m and the cell width is 440m. The work described here built a groundwater flow model in the micro-watershed using Visual MODFLOW Flex. The steady-state groundwater flow model was then numerically projected in April 2020 using seventeen observation wells using the present stress levels. The model aims to quantify input and output stresses and pinpoint the basin's overstressed regions. The water budget analysis estimates that evapotranspiration loss makes up 56.54% of the basin's total groundwater recharge while overall groundwater leaks from river systems are 28.72%. The findings indicated that the southern section of the basin is undergoing severe aquifer stress as a result of river overflow and evapotranspiration. To improve groundwater levels, it is suggested that artificial recharge structures should be developed in and near Chikkodi village at appropriate sites. The trial-and-error approach was used to assess the sensitivity of the calibrated model, and it was discovered that the model is extremely sensitive to changes in hydraulic conductivity and recharge levels. Model performance is excellent, with R2, RMSE, and NRMSE values of 0.97, 5.34, and 13.23% of the assessing criteria.

Simulation of groundwater flow and seawater intrusion in response to climate change and human activities on the coastal aquifer of Gaza Strip, Palestine

This study has investigated the potential impact of human activities and climate change on the groundwater budget, water levels, and seawater intrusion in the coastal aquifer of the Gaza Strip (State of Palestine) over the next two decades. The impact of a proposed measure to use alternative freshwater provision from desalinated seawater on the future groundwater quantity and quality was also analyzed. Following extensive analysis of available observed data, a three-dimensional groundwater flow model, coupled with variable-density saltwater flow and transport components, was utilized for the investigations. Compared with the benchmark scenario (SC0), the climate change scenario (SC1) suggests that over the next two decades, an average annual aquifer recharge of 6.3 Mm3 can be expected, while the human activities scenario (SC2) indicates that the groundwater levels will decline at a rate of 0.09 m/year with expected urban area expansion. The combined human activities and climate change scenario (SC3) indicate severe groundwater storage depletion and seawater intrusion over the next two decades. The alternative freshwater provision scenario (SC4) indicates a strongly positive response in groundwater recovery (quantity and quality) over the next decades. The findings of this study emphasize strongly that the human activity impact, rather than climate change, is the driving force of groundwater depletion and that groundwater recovery interventions will be crucial in the future and should be implemented urgently.

Efficacy of Permeable Reactive Barriers in Mitigating Tetrachloroethene Ingress into Highway Drainage Concrete Pipe in Saturated Media

Work herein is focused on evaluating factors affecting tetrachloroethene (PCE) contaminant ingress into the subsurface concrete pipe embedded in the saturated soil profile and assessing the efficacy of permeable reactive barriers (PRB) in mitigating PCE concentration. A three-dimensional groundwater flow and solute transport numerical model is established using MODFLOW paired with reactive transport (RT3D) software, in which the model is developed using a finite-difference numerical scheme. The analyses parameters are developed from data for a site in Wilson, North Carolina, at which subsurface chlorinated organic solvents from a dry-cleaning facility occurred in the presence of subsurface highway concrete drainage pipe. Modeling results after 10 years of simulation period indicated that the natural attenuation process taking place in the native soils with coefficients of KPCE=0.00019 d−1, and 0.0033 d−1 reduced the PCE concentrations breaking through the concrete pipe by 30.7% and 34.1%, respectively. On the other hand, with a greater percent of the soil sorption as manifested by organic carbon content, the PCE concentration breaking through the pipe increased by 137% for the same simulation period as a result of the prolonged presence of PCE concentration within the pipe trench. The hydraulic conductivity of the PRB (kPRB) modestly affects the level of PCE breaking through the pipe, while the increase in thickness of the PRB was found to be the most effective in decreasing the level of PCE ingress into the pipe.

Groundwater Assessment using Numerical Flow Model: A Case Study in Gash Sub-Basin-Kassala State, Sudan

The main objective of groundwater modelling in Gash River Sub-basin, is to investigate the effect of hydrologic, hydrogeological parameters and stresses on hydrodynamic behaviour through the implementation of a realistic three-dimensional groundwater flow model. Severe decline of water level due to uncontrollable heavy abstraction, exposes a water scarcity problem especially in summer seasons. The model was developed for four geological layers encompassing two aquifer zones. The improved three-dimensional visual MODFLOW Code was selected, implemented and run using WHS method to solve the finite difference equation using trail-and-error calibration procedure at Kassala Area. The transient model was successfully calibrated with acceptable results of model calibration criteria. The contour maps of the simulated heads were performed as potentiometric surface. The general flow direction of the groundwater is from southeast towards northwest part of the area and from Gash River course towards the east and west directions as detected from gradual decreasing of potential line’s values in those directions, confirming the aquifer recharge from Gash River. The similarity of potentiometric surface contour maps of the two aquifers confirm the aquifers hydraulic interactions. It is found that the increasing pumping rate caused considerable increase in drawdown as detected from pumping rate incremental scenarios. Moreover, incremental pumping rate scenarios also reflected increasing river leakage into the aquifer system due to disturbance of water balance due to water level decline. The components of water budgets were calculated and its percentage was performed for the hydrologic balance. The difference between inflow and outflow of the water balance shows a deficit in most stress periods of the model simulations. Calibration fitness was accomplished at most of the observation wells suggesting that the groundwater model is an accurate representation of the actual historic groundwater system and confirm the validity of the model to forecasting purposes. It was found that the model is more sensitive to hydraulic conductivity and least sensitive to specific yield (Sy). Hence, precaution should be revealed for hydraulic conductivity in forecasting model usage.

Generic workflow of groundwater flow simulations in geologically complicated domains with millions of unstructured grids

Numerical groundwater flow simulation involves manual and tedious pre-processing and post-processing procedures. Hence, this study developed a systematic and efficient workflow to alleviate model buildup and data-processing burdens, allowing researchers to focus on the application aspects of simulation results. This highly automatic workflow allows researchers to execute three-dimensional groundwater flow simulations in sites with complex hydrogeological conditions. Processes in the workflow are formed as a trilogy: building a hydrogeological conceptual model, generating a site-specific unstructured mesh and specifying simulation conditions, and executing the simulation and post-processing results. The workflow feasibility has been demonstrated by simulating the three-component (water, brine, and air) fluid flow in Huayu Islet, the only andesitic island of the basaltic Penghu archipelago, using TOUGH3 (Transport of Unsaturated Groundwater and Heat version 3) and its EOS7 (Equation of State #7) fluid module. Our self-developed mesh generator can produce a locally refined unstructured mesh with millions of grid cells that can capture the essential geological features of Huayu. It was found that, of the three scenarios considered, only the one using a fine mesh coupled with a two-phase Dirichlet boundary condition at the top surface could obtain a physically meaningful bowl-shaped fresh water and brine interface and reasonable transport pathway characteristics. In summary, the developed workflow serves as a practical methodology to authentically characterize the hydrogeologic mechanisms of a site with complicated geology.

Heterogeneity-Driven Hydrodynamics Conditions the Hydrochemistry of Spring Water in Volcanic Islands.

Perched aquifers represent significant unexploited groundwater reserves in volcanic islands and contain valuable freshwater resources. These water reserves provide critical resources to indigenous populations suffering water scarcity. Groundwater discharged from a perched aquifer into two adjacent (14 m) springs in the volcanic summits constituted by basaltic and pyroclastic deposits of Gran Canaria Island (Spain) was examined. Based on springs discharge data, a three-dimensional groundwater flow and solute transport model of the investigated perched aquifer was calibrated to reproduce its hydraulic regime, as well as to explain the hydrochemical and isotopic composition of its main discharge systems, the studied springs. Groundwater flow simulations effectively replicated flow paths of the two springs affected by the existing geological heterogeneities, with differential travel times of 246 and 130 years, respectively, and with a convergent flow toward them partially explaining the averaged differences in electrical conductivity, δ18 O, and tritium observed between the springs. It can be concluded that, although water quality in both springs is similar and homogenous, as they come from the same aquifer system, geological heterogeneities in the upper elevation volcanic areas is likely the cause for the differences in the residence times of the two springs, which suggests that the flow regimes for the two springs are independent. The chemistry of the two springs, however, is essentially the same, with the exception of tritium, which is used to ascertain residence time.

Analytical solutions of contaminant transport in homogeneous and isotropic aquifer in three-dimensional groundwater flow.

Modeling three-dimensional contaminant transport released from arbitrary shape source geometries is useful in hydrological and environmental sciences. This article produces several analytical solutions for three-dimensional contaminant transport in a homogeneous and isotropic aquifer by using Green's function with the groundwater flow which is assumed to be in three directions. The solutions are obtained for both finite depth aquifer and semi-infinite depth aquifer. Various types of sources are discussed: point, line, plane, or cuboid sources. The continuous and instantaneous sources are also investigated. A MATLAB coding is developed to calculate the numerical integrals which occur at the solutions. Some solutions are verified with the solutions obtained in the literature. This study confirms the effect of groundwater velocities in all directions on the degree and the directions of contaminant spreading. Additionally, the results highlight the significant effect of the geometrical shape of the contaminant sources on contaminant concentrations for instantaneous and continuous sources. In particular, the cuboid source and the horizontal rectangular source provide the highest concentrations. The analytical solutions developed in this article can be applied for a wide range of contaminant transport.

Hydrogeological Model of the Forefield Drainage System of Werenskioldbreen, Svalbard

The significant recession of Arctic glaciers caused by climate warming is expanding their proglacial zones. Thus, their importance for the hydrology of glacierised basins is growing. In contrast to the surface waters in such areas, the role of groundwater in the hydrological balance of Svalbard catchments is poorly known. This paper presents the hydrogeological conditions and groundwater flow within the permafrost active layer in the forefield of the Werenskioldbreen glacier basin (44.1 km2), 61% of which is glacierised. Based on field studies of groundwater in the 2017 ablation season and laboratory analyses of the hydrogeological properties of proglacial sediments, a three-dimensional groundwater flow model (FEFLOW) for part of the glacier forefield (4.8 km2) was developed. The main results show the components and characteristics of the groundwater balance and indicate the preferential groundwater flow paths. The volume of water retained in the sediments of the marginal zone is 1.0073 mln m3. The maximum potential free pore space that could be filled by water is 2.0689 mln m3. The calculated groundwater discharge for average conditions is 6076.9 m3 d−1, which is about 2% of the total seasonal catchment runoff from the main glacial river. The results of the spatial analysis for the groundwater depth and the groundwater flow directions are also presented. There need to be further detailed studies of hydrogeological processes in glacial basins in Svalbard in order to develop existing knowledge.

Delineation of spring capture zones in southern Great Basin, USA based on modeling results and geochemical data

The protection zones or capture zones of springs in desert environments can be hard to identify, but they are critical to spring protection. Most springs fed by regional aquifers are susceptible to contamination and groundwater development. The U.S. Environmental Protection Agency has established hydrogeologic mapping methods to delineate protection zones for springs. However, it is often difficult to determine a regional aquifer system's flow pattern with this technique alone, and the use of these methods is not conducive to efficient groundwater management. Particle tracking analysis using a well-conceptualized and calibrated numerical model for the three-dimensional groundwater flow domain feeding a given group of springs can help facilitate the identification of spring capture zone boundaries. Building upon this basis, a multifaceted approach was developed to define clear boundaries of the capture zones for the springs in the Furnace Creek, Ash Meadows, and the Muddy River areas in the southern Great Basin, USA. Capture zones were first delineated from inverse particle tracking and Hydrologic Unit 12 watersheds. Afterwards, they were adjusted based on water budgets, geology, and hydrologically significant faults. Finally, a geochemical analysis of the groundwater chemistry and isotopic data was conducted to verify the extent of each spring capture zone. This multifaceted approach adds confidence to the new delineations.

GEOPOLIS software tools – Groundwater flow modeling at deep repository of liquid radioactive waste at Severny test site

This article discusses a three-dimensional groundwater flow model of a deep disposal facility at Severny test site. The three-dimensional model is a part of the certified software GEOPOLIS, based on the hydrogeological code GeRa (Geomigration of Radionuclides) serving as the calculation engine. This study describes the hydrogeological patterning of the groundwater flow model, as well as the results of calibration and verification of the model water heads with respect to the data of monitoring for more than 40 years of the deep repository exploitation. The article begins with a brief overview of the previously developed hydrogeological models of this object and continues with a description of the geological structure of the territory, and with a substantiation of the boundaries and parameters of the model. The results of groundwater flow modeling, model calibration, verification and estimation of discrepancy between the model results and monitoring data are shown. The comparison of the modeled and observed water heads in the stationary conditions (before the start of injection) and during operation of the deep repository allows making conclusion on the quality of calibration.

Evaluation of Water Quality Impact Caused by Common Hazardous Waste Landfill Facility in Gummidipoondi, Tamilnadu India

The aim of the study was to evaluate the water quality impact caused due to the operations of common hazardous waste landfill facility (CHWLF) in Gummidipoondi industrial estate, Tiruvallur district, Tamilnadu, India. The watershed area of the hazardous waste landfill facility was delineated using Arc-GIS tools and prediction of ground water flow direction was carried out using three-dimensional ground water flow model using VISUAL MODFLOW software. The water quality analysis was performed in the upstream and downstream directions of the project site and the results showed that all the tested parameters were within the BIS 10500:2012 drinking water limits, except pH which showed slightly acidic characteristics in certain locations. The tested water samples mostly belonged to the Ca + Mg-HCO3’ type as classified using the multivariate analysis method using piper diagram. Co-relation between the water quality parameters were determined using statistical analysis of Pearson’s correlation coefficient (r) values.

Three-dimensional groundwater flow modeling to assess the impacts of the increase in abstraction and recharge reduction on the groundwater, groundwater availability and groundwater-surface waters interaction: A case of the rib catchment in the Lake Tana sub-basin of the Upper Blue Nile River, Ethiopia

Study regionRib catchment in the Lake Tana sub-basin, Upper Blue Nile River, Ethiopia. Study focusThis paper aimed to assess the impacts of future increase in abstraction and recharge reduction on the groundwater, groundwater availability, and groundwater-surface waters interaction based on a three-dimensional groundwater flow modeling. Calibration was made under the steady state condition. Scenario analysis performed for 1) increase in abstraction, 2) decrease in recharge, 3) the worst-case scenario that combined the aforementioned two scenarios and with additional extraction for irrigation, and 4) for the optimal-case scenario, which considers 5% recharge increase for the worst-case scenario model. New hydrological insights for the regionIt is found that the groundwater flows from uplands toward the Tana Lake. The total inflow to and outflow from the system in the calibrated model are 1733480 m3/d and 1840451 m3/d, respectively. Groundwater level drop, reduction in base flows to surface waters, and in evapotranspiration flux compared to the calibrated values encountered for all scenarios, which are significant (mean 38.4 m, 28.5–100 %, and 97.8 %, respectively) for the worst-case scenario. On the other hand, an increase in groundwater level (mean 9.8 m), base flows (0–14.4 %), and evapotranspiration flux (29.5 %) observed for the optimal scenario when compared to the worst-case scenario results. Results suggest that groundwater management measures should be implemented to mitigate the impacts.

The potential impacts of a water transfer project on the groundwater system in the Sugan Lake Basin of China

The ungauged Sugan Lake Basin represents a candidate area for development of a water transfer scheme to satisfy the water requirement of Dunhuang city in northwestern China. In this work, multisource data, including river runoff, groundwater levels and remote-sensing data, and field investigation records, were collected and analyzed. A three-dimensional groundwater flow model was constructed using FEFLOW software to predict the potential influence of the transfer project on the groundwater system. Results show that infiltration from the Great Harten River is the main driving factor of groundwater-level fluctuation and groundwater recharge. Scenario analysis under four water transfer conditions found that the drawdown of groundwater gradually decreases from east to west. If the water transfer scale reaches 1.2 × 108 m3/a, after 100 years, the maximum drawdown of groundwater is noted at 68.02 m, and the flow rate of the Middle Spring reduces by 25.7%. In the western wetland, the area over which the groundwater level is lowered by more than 4 m is 10.21 km2, and natural succession may occur or vegetation cover may decline. The results of this study will aid in water resource planning based on a rational amount of water transfer, and provide further protection of the wetland ecology.

Application of numerical modeling to reservoir immersion assessment and control in dual-formation hydrogeological unit

Abstract Reservoir immersion is a serious environmental geological issue in a dual-formation structural reservoir bank (DFB) induced by dynamic surface water impoundment (SWI) that has implications for low-lying farmland and buried infrastructure. It is a major challenge to identify the dynamic immersion process and make economic and scientific joint mitigation measures for controlling groundwater immersion. Here, we develop a three-dimensional groundwater flow model and apply it to evaluate and control reservoir immersion in the typical low-lying DFB of Xingan Navigation and Power Junction Project (XGNPJ) across Ganjiang River in Jiangxi Province, China. The field-scale model is well calibrated to predict where the groundwater immersion could potentially occur. Furthermore, the effectiveness of the countermeasures adopted for the reduction of reservoir immersion areas were analysed based on the simulation model by considering the projected future combination scenarios of engineering measures. Results indicate that without engineering mitigation measures, SWI generates groundwater inundation across 23% of the total study area. Comprehensive comparative analysis on different seepage control schemes reveals that the joint engineering measures can effectively control the immersion range to 5% of the total area. The findings can provide scientific basis for groundwater immersion assessment and guide immersion control of XGNPJ project.