Analysis Of Groundwater Flow Research Articles

Hydrogeologic Framework Model‐Based Numerical Simulation of Groundwater Flow and Salt Transport and Analytic Hierarchy Process‐Based Multi‐Criteria Evaluation of Optimal Pumping Location and Rate for Mitigation of Seawater Intrusion in a Complex Coastal Aquifer System

AbstractA series of hydrogeologic framework model (HFM)‐based steady‐ and transient‐state numerical simulations is performed first using a coupled subsurface flow‐transport numerical model to analyze groundwater flow and salt transport in an actual three‐dimensional complex coastal aquifer system before and during groundwater pumping. A series of analytic hierarchy process (AHP)‐based multi‐criteria evaluations is then performed applying a multi‐criteria decision‐making approach to determine optimal pumping location and rate for a new pumping well in the complex coastal aquifer system during groundwater pumping. The complex coastal aquifer system is composed of six anisotropic fractured porous geologic media (five rock formations and one fault) and three isotropic porous geologic media (three soil formations) and shows high geometric irregularity and significant heterogeneity and anisotropy of the nine geologic media. Results of the steady‐state numerical simulations show successful model calibration with 26 measured groundwater levels and two observed seawater intrusion front lines. The latter two are determined by spatial interpolation and extrapolation of electrical conductivity logging data and electrical resistivity survey data, respectively. Based on the status and prospect of necessary water uses and available groundwater resources, the field observations of groundwater and seawater intrusion, and the analyses of the steady‐state numerical simulation after the model calibration, six candidate pumping locations are selected for the new pumping well. In addition, from six preliminary individual transient‐state numerical simulations, maximum pumping rates at the six candidate pumping locations are calculated first, and a set of six incremental candidate pumping rates is then assigned at each of the six candidate pumping locations. Results of the transients‐state numerical simulations show that groundwater flow and salt transport are spatially and temporally changed, and seawater intrusion is further intensified by groundwater pumping. In addition, the magnitudes of such spatial and temporal changes and intensification are significantly different depending on the candidate pumping locations and rates. Results of the steady‐ and transient‐state numerical simulations also show that both complexity (geometric irregularity, heterogeneity, and anisotropy including the fault) and topography have significant effects on the spatial distributions and temporal changes of groundwater flow and salt transport in the coastal aquifer system before and during groundwater pumping. In addition, results of statistical estimations of the mesh Peclet and Courant numbers confirm acceptabilities of minimizing numerical dispersion in the steady‐ and transient‐state numerical simulations. Based on the analyses of the transient‐state numerical simulations, eight multiple criteria are chosen to judge, prioritize, and rank the six candidate pumping locations and six candidate pumping rates for optimal pumping. Results of the multi‐criteria evaluations determine the optimal pumping location and rate for the new pumping well among the six candidate pumping locations and six candidate pumping rates. In addition, results of consistency checks confirm consistencies of judgments in the multi‐criteria evaluations.

Mathematical Modeling of Transient and Steady-State Groundwater Flow in a Confined Aquifer

Groundwater flow problems can be expressed mathematically with the employ of partial differential equations and which could be solved analytically or numerically. The results obtained showed that the direction of flow of groundwater is from a region of higher hydraulic head to a lower hydraulic head, and that pumping groundwater from the well faster than it is recharged leads to dry wells. The numerical methods used for the analysis of Transient and steady-state groundwater flow produced efficient, effective and accurate solution and can be used for all real-life problems.

Modeling groundwater flow with random hydraulic conductivity using radial basis function partition of unity method

Simulating groundwater flows in heterogeneous aquifers is one of the most widely studied problems. The heterogeneity is modeled through random hydraulic conductivity fields log-normally distributed. In this paper, we aim to generate the realization of the log-normal hydraulic conductivity by summing up a finite number of random periodic modes with the Kraichnan algorithm. To address Neumann conditions, we propose a change of variables that results in Dirichlet boundary conditions along all boundaries of the computational domain. Then, we suggest using the radial basis function partition of unity method (RBFPUM) and RBFPUM with QR factorization (RBFPUM-QR) to analyze groundwater flow in the heterogeneous porous medium. We evaluate the performance of the proposed methods by increasing the number of random modes and the variance of the log-hydraulic conductivity fields using Gaussian and exponential correlation. In addition, we verify the effectiveness of the presented approaches in one and two dimensions using the method of manufactured solutions. Furthermore, we provide statistical inferences through Monte Carlo simulations. Numerical results demonstrate that RBFPUM-QR performs well in handling higher heterogeneity in both single realizations and Monte Carlo simulations.

New particle tracking method for 2D steady-state groundwater flow around wells: A modified algorithm using the stream function

Particle tracking is an essential process in analyzing groundwater flow and solute transport in aquifers. A drawback of existing particle tracking methods, which are based on approximate estimations of the velocity in a time step, is the accumulative errors of numerous time steps would lead to deviation of particles away from the exact streamlines, especially when pumping and injecting wells exist. In this study, to improve the accuracy of particle tracking for the two-dimensional (2D) steady-state flow around wells, we propose a stream-function-based (SFB) particle tracking method in which a particle is traced along the exact streamline with a given value of the stream function, and the branch cut effect caused by the multivalued stream function around a well is eliminated. Three synthetic cases are used to demonstrate the advantages of the SFB method over the existing Pollock method and the fourth-order Runge-Kutta method. In the cases of a single pumping well and an injecting-pumping well pair, the Pollock and Runge-Kutta methods yield pathways that may be far away from the exact streamline, but the SFB method performs much better. In the case with a pumping well and two injecting wells, the SFB method successfully delineated a narrow capture zone of the pumping well, which requires a high accuracy particle tracking process. Moreover, the accuracy of particle positions obtained by the SFB method is insensitive to the step-travel distance. The study would be useful for accurate investigation of flow fields in aquifers disturbed by wells.

Machine Learning in Civil Engineering - on the example of prediction of the coefficient of permeability

This paper investigates the application of the machine learning techniques in the civil engineering, focusing on the prediction of permeability coefficient. Permeability coefficient is an important parameter in various civil engineering projects including groundwater flow analysis, soil stabilisation and geotechnical engineering. Traditional methods for estimating permeability are time-consuming and often based on laboratory tests. The machine learning offers a promising approach to predict it more efficiently and accurately. This paper studies several machine-learning techniques, verifying their applicability to predict the permeability coefficient for sands. The article analysed the predictive performance of the artificial neural network (ANN), the random forest (RF), the gradient boosting (GB) and the linear regression (LR). The most accurate algorithm in this case turned out to be the gradient boosting for which the coefficient of determination was 0.995, the mean absolute error was less than 0.001 and the root mean square error was 0.001.

Theis equation revisited: From infinite to finite aquifer and from fully to partially penetrating well

The Theis equation has seen widespread use in the fields of hydrogeology, groundwater flow analysis, and pumping test analysis. Originally derived from the principles of heat conduction with an assumption of an infinite line heat source, this equation has been widely applied in hydrogeology. However, in reality, wells have finite lengths, and the implications of assuming an infinite length have not been thoroughly explored.This study aims to derive and validate an analytical solution for flow towards wells in a confined aquifer while considering both a finite well length and the presence of aquifer boundaries, using a point-source approach. The resulting solution can also account for anisotropy in the porous media and applies to both fully and partially penetrating wells. To assess its accuracy, the study compares its results with those obtained from the Theis equation and a numerical model, which serves as a benchmark.This study considers two scenarios: one with a relatively large screen length compared to the aquifer thickness, and the other with a relatively small screen length in comparison to the aquifer thickness. The study's findings indicate that the Theis equation accurately represents outcomes only when the screen length-to-aquifer thickness ratio is high. However, the Theis equation falls short when this ratio is small, which is often the case in the majority of pumping wells. In such situations, the Theis equation tends to significantly underestimate or overestimate the actual drawdown in the aquifer, with the extent of error depending on the proximity to the well screen.

Quantitative analysis and modeling of groundwater flow using visual MODFLOW: a case from subtropical coal mine, northwest Bangladesh

Quantitative analysis and modeling of groundwater flow using visual MODFLOW: a case from subtropical coal mine, northwest Bangladesh

Assessment of installation suitability of a vertical closed loop ground source heat pump system in regional scale

Installation suitability of a vertical closed loop GSHP system in the Echigo Plain of Japan was assessed considering the regional scale groundwater flow and heat transport analysis. For evaluating and understand the variation of development potential of the system, the necessary length of ground heat exchanger (GHE) was analyzed at different points, where groundwater, geology and subsurface temperature distribution varies. The computation was done for the model case of the Japanese single-family dwelling with reference to standard for energy saving in Japan. The necessary length of GHE ranged from 67 m to 101 m within the plain and found comparatively longer at the central coastal area around the Niigata City. These results showing the variation of the necessary length of GHE in the plain scale is significant and essential for the proper design and site selection of the system in the Echigo Plain, and can also be beneficial for the development of GSHP system in Japan. Influence of the existing groundwater pumping system was also evaluated to determine if the pumping system can enhance heat exchange performance for space-heating. The effect of groundwater pumping was not so significant to improve heat exchange rates due to the natural existence of groundwater flow.

Study on borehole sealing corresponding to hydrogeological structures by groundwater flow analysis

Study on borehole sealing corresponding to hydrogeological structures by groundwater flow analysis

Analyse de l’écoulement des eaux souterraines du pergélisol dans un pergélisol alpin de basse latitude, à l’aide d’un modèle de simulation: une étude de cas dans la région amont du Fleuve Jaune, sur le Plateau du Quinghai-Tibet, Chine

Analyse de l’écoulement des eaux souterraines du pergélisol dans un pergélisol alpin de basse latitude, à l’aide d’un modèle de simulation: une étude de cas dans la région amont du Fleuve Jaune, sur le Plateau du Quinghai-Tibet, Chine

A comprehensive computer aided approach to design of earthen dams of dry flood-control reservoirs

A generalized, comprehensive approach to geotechnical design of earthen dams of dry flood-control reservoirs is developed. It consists of three steps:•In Step 1 three-dimensional (3D) model of terrain and dam subsoil is created. The arrangement of geotechnical layers is reconstructed based on results of geotechnical investigation using geostatistical interpolation, namely, kriging.•Step 2 involves 3D finite element (FE) analysis of transient groundwater flow through the subsoil. Anti-filtration barrier extent is determined by appropriate parametric analysis and the condition of critical hydraulic gradients is verified.•Step 3 concerns deformation assessment and stability analysis. Computations are carried out for selected cross-sections of the dam. At this stage transient coupled problem of deformation and groundwater flow is considered. Stability is assessed with the use of shear strength reduction technique.The proposed approach enables verification of all relevant conditions of limit states. Furthermore, it has been developed in such a way as to enable computationally efficient analysis of considered phenomena. The method constitutes a general framework of design procedure. It can be easily adapted to conform any standard requirements, e.g., by taking adequate values of partial safety factors. Moreover, design solutions can be optimized through parametric analyzes.

Analysis of Groundwater Overexploitation Based on Groundwater Regime Information.

Although groundwater overexploitation is a global problem, there are no unified standards for its identification and determination. To date, groundwater overexploitation has mainly been evaluated using the groundwater quantity balance and effect of groundwater exploitation on the environment. However, it is difficult to determine groundwater exploitation for an agricultural irrigation area owing to the lack of detailed environmental monitoring data. We used the experience of previous studies to introduce a novel identification model for groundwater overexploitation by relying on groundwater regime information and multi-factor analysis. The model was applied to the Songhua River-Naoli River area, Sanjiang Plain (China). In the demonstrated model, the study area was divided in the context of the risk of overexploitation into natural and non-natural regime areas according to groundwater regime characteristics. The areas were identified by analyzing groundwater flow fields, cones of groundwater depression, and storage variation. The analysis demonstrated that the study area could be divided into high-risk, medium-risk, low-risk, and non-overexploitation areas with corresponding area ratios of 10.12%, 1.38%, 54.8%, and 33.7%. Moreover, the total amount of overexploited groundwater was estimated to be 30.41 × 108 m3 (average annual decrease=1.69 × 108 m3 ). Overall, the proposed identification model was shown to be applicable to agricultural irrigation areas, thereby offering promising implications.

Analysis of groundwater age and flow fractions for source-sink assessments

ABSTRACT Capture zone analysis has been a prominent aspect in managing water supply wells. The study of aquifer vulnerability and protection also employs groundwater age modeling. Therefore, a comprehensive analysis of capture zones and groundwater age was used to propose a new method to understand the age fractions of water reaching pumping wells. The concept was derived from a volume-weighted approach for finding the mean age of a multi-component groundwater mixture. Numerical analysis of groundwater flow, age transport, and capture zone delineation was carried out to obtain volume-weighted mean groundwater age at the well. Thus, the groundwater age reaching a pumping well was easily assessed by computing age fractions. An additional recharge well rendered the groundwater age 25 days younger than that with a pumping well alone at 450 days. The example application described how the results could estimate the mean groundwater age at the sink point, contributed from the various sources.

Mass fluxes of dissolved arsenic discharging to the Meghna River are sufficient to account for the mass of arsenic in riverbank sediments

Shallow (<30 m) reducing groundwater commonly contains abundant dissolved arsenic (As) in Bangladesh. We hypothesize that dissolved As in iron (Fe)-rich groundwater discharging to rivers is trapped onto Fe(III)-oxyhydroxides which precipitate in shallow riverbank sediments under the influence of tidal fluctuations. Therefore, the goal of this study is to compare the calculated mass of sediment-bound As that would be sequestered from dissolved groundwater As that discharges through riverbanks of the Meghna River to the observed mass of As trapped within riverbank sediments. To calculate groundwater discharge, a Boussinesq aquifer analytical groundwater flow model was developed and constrained by cyclical seasonal fluctuations in hydraulic heads and river stages observed at three sites along a 13 km reach in central Bangladesh. At all sites, groundwater discharges to the river year-round but most of it passes through an intertidal zone created by ocean tides propagating upstream from the Bay of Bengal in the dry season. The annualized groundwater discharge per unit width at the three sites ranges from 173 to 891 m2/yr (average 540 m2/yr). Assuming that riverbanks have been stable since the Brahmaputra River avulsed far away from this area 200 years ago and dissolved As is completely trapped within riverbank sediments, the mass of accumulated sediment As can be calculated by multiplying groundwater discharge by ambient aquifer As concentrations measured in 1969 wells. Across all sites, the range of calculated sediment As concentrations in the riverbank is 78–849 mg/kg, which is higher than the observed concentrations (17–599 mg/kg). This discovery supports the hypothesis that the dissolved As in groundwater discharge to the river is sufficient to account for the observed buried deposits of As along riverbanks.

Examination of Source Control Measures by Applying Groundwater Flow Analysis to Abandoned Mines in Japan

Examination of Source Control Measures by Applying Groundwater Flow Analysis to Abandoned Mines in Japan

Analysis of Groundwater Flow for Saltwater Interaction Range Using Visual Modflow: A Case Study of Coastal Belt in Srikakulam District of Andhra Pradesh, India

Groundwater flow modeling is one of the important tools to know the direction and magnitude of groundwater flow along the coastal aquifer. A study carried out in the coastal belt of Srikakulam showed a region where there is a probable mixing of ground water with the sea water. In the present investigation, the ground water flow and velocity are determined by using ModFlow Software. The entire study area has been divided into small grids. The wells are identified and located in eight lines perpendicular to the coastal belt. In this investigation, 97 existing wells are selected for carrying out the study. The distribution of the hydraulic head was estimated through a 20-year simulation. The observed results indicate that a considerable advance in seawater intrusion can be expected in the coastal aquifer of the study area. It is concluded that the average velocity of ground water in the Srikakulam coastal belt is 1.1 m/day. The results help to determine the groundwater flow channels and also help to explain the ground water recharge and flow areas in the aquifer.

Analysis of Groundwater Flow on Hydrogeological for Sustainable Development and Environment in the Ternate Basin, North Maluku Province, Indonesia

The sustainability of water and sanitation management is an important point in the 2021 SDGs program. To support the program, it is important to understand Indonesia's water cycle. Given the variety of characters, topography, and geology between islands in Indonesia can distinguish hydrogeological systems and their interactions with the surrounding environment. The design and management of water resources, especially groundwater, has an important role, considering the basin area is 106 km2, the character of a volcanic island with the name of an active volcano. Topography from 0-8% is a built-up zone, 8-14% is a cultivation zone, 14-45% is a protected forest, and &gt;45% is a stratovolcano peak zone. Island morphology affects groundwater flow patterns. This study aimed to determine the characteristics of groundwater flow in the Ternate basin. Purposive sampling of 56 production wells, transmissivity value, conductivity, aquifer thickness, and topography was analyzed using the Cubic spline interpolation method. The results showed that the direction of flow and groundwater accumulation based on groundwater modeling using the kriging interpolation technique resulted in the interaction of groundwater flow and depression cones in 56 production wells due to the concentration and massive groundwater abstraction in the Ternate Basin. The decrease in groundwater level is fluctuating, from groundwater flows that occur radially-centrifugally, the total reserves of 56 production wells are 46 million m3/day, the average transmissivity value is 2.17 m2/day, production discharge is 51,710 m3/day.

Groundwater Flow Analysis for Inclined Aquifers.

Sedimentary deposits that have water in subsurface groundwater system are not often completely horizontal because of the geological features such as: bedding and folding. These deposits typically overlay on sloped impervious layers, and therefore; additional research is necessary for these situations. In this research an analytical model is presented for groundwater flow on inclined impermeable layer. The presented model is preferable to the Paolowsky method regarding its applicability and accuracy. The Dupuit's assumption is used for the formulation. The presented model can be generalized for the situation, having surficial infiltration into and exfiltration from the groundwater system. Several problems of different slope situations and boundary conditions are addressed by the presented model and the results are shown here. The model is compared with numerical model Seep/w and good agreements are obtained when possible.

A Study on Groundwater Flow Analysis of the Tedori River Alluvial Fan Using Distributed Tank Model

A Study on Groundwater Flow Analysis of the Tedori River Alluvial Fan Using Distributed Tank Model

An Analysis of the Groundwater Flow s Characteristics Following CLIMATE CHANGES

Purpose: The purpose of this study is to estimate the groundwater volume available in the Gyeongju region and predict changes in the groundwater flow s characteristics based on the IPCC RCP climate scenario. Method: As for the method to carry out this study, the results of forecasting the weather conditions in the Gyeongju region based on the IPCC RCP climate change scenario were used. By using the predicted precipitation data, the groundwater volume available was analyzed by using the SWAT MODEL. To analyze the groundwater flow s characteristics, the future groundwater flow s characteristics were analyzed by using MODFLOW by using the observed water level related data. Results: When examining the content by scenario, and across all scenarios, it was analyzed that the M3 basin was the largest, followed by the M2 basin and the M1 basin, respectively. It was also analyzed to be inversely proportional to the size of the outflow hydrologic curve in the case of the M1 basin as the city area was greater than that of the M2 and M3 basins. It was analyzed that the scenario of RCP 2.6 had the lowest variation for the content by basin, and that RCP 4.5 had the largest variation by basin. In terms of the flow direction of the groundwater, the M3 basin flows from the mountainous terrain to the Deokdongcheon Stream along the Deokdong Lake, and the M2 basin flows from the south towards the direction of the Bomun Lake. The M1 basin was analyzed to be the Bukcheon basin and finally flows towards the west side of the Hyeongsan River, and the overall groundwater flow in the target basin was analyzed to flow along the river towards the west side of the Hyeongsan River. Conclusion: As a result of analyzing the groundwater volume available and flow’s characteristics in the Gyeongju region according to climate changes in this study, the amount of groundwater volume available in the future RCP scenario both increased in 2100 compared to the current precipitation. Yet, in the case of RCP 4.5, the duration of no precipitation decreased by 57.75% compared to 2020, and RCP 8.5 increased by 56.79%, and hence, it was analyzed that, as for the available volume in 2100, the RCP 4.5 scenario was calculated to be 6.93% higher than the present, and the RCP 8.5 scenario increased by 0.10% compared to the present. In 2100, when there was no precipitation for 40 or more days, it was analyzed that the groundwater level decreased for RCP 4.5 by 0.7 m on average, and as for RCP 8.5, it was analyzed to decrease by GL by 1.0 m, and hence, the water level’s decrease turned out to be very large for the RCP 8.5 scenario. As a result of the groundwater flow analysis, it was analyzed that it was advantageous for securing the groundwater because of the high groundwater volume available and the groundwater level in the RCP 4.5 scenario where the greenhouse gas reduction policy was significantly realized.