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1
VAN HERWAARDEN, ONNO A., und JOHAN GRASMAN. „DISPERSIVE GROUNDWATER FLOW AND POLLUTION“. Mathematical Models and Methods in Applied Sciences 01, Nr. 01 (März 1991): 61–81. http://dx.doi.org/10.1142/s0218202591000058.
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By solving asymptotically the Dirichlet problem for the backward Kolmogorov equation describing the random walk of a particle in a dispersive flow, it is computed at what rate contaminated particles cross the boundary of a protected zone. The method also yields an estimate of the expected arrival time.
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Wang, Yan, Wen Xia Wei, Hui Ling Han und Ying Wang. „Groundwater Migration Modeling and Parameter Sensitivity Analysis on Contaminated Site“. Advanced Materials Research 878 (Januar 2014): 775–81. http://dx.doi.org/10.4028/www.scientific.net/amr.878.775.
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Contamination control and remediation of groundwater is one of the hotness points in environmental protection field. Groundwater contamination numerical simulation is widely used for groundwater contamination transportation. In this paper, we constructed an indoor sandbox to conduct hydraulic control experiment and tracer experiment. We also set up groundwater flow model and solute transport model by computer and chose the model's key parameters for sensitivity analysis. The results indicated that the sensitivity of hydraulic conductivity was highest, which was the key parameter in the groundwater flow model. The sensitivity analysis of solute transport model parameters showed that sensitivity from large to small was: longitudinal dispersion, porosity and hydraulic conductivity. This study can obtain the main parameters in groundwater simulation model and is helpful for the construction of groundwater contamination migration model.
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Ji, Xiaohui, Tangpei Cheng und Qun Wang. „CUDA-based solver for large-scale groundwater flow simulation“. Engineering with Computers 28, Nr. 1 (19.02.2011): 13–19. http://dx.doi.org/10.1007/s00366-011-0213-2.
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Kupfersberger, Hans, Gerhard Rock und Johannes C. Draxler. „Combining Groundwater Flow Modeling and Local Estimates of Extreme Groundwater Levels to Predict the Groundwater Surface with a Return Period of 100 Years“. Geosciences 10, Nr. 9 (18.09.2020): 373. http://dx.doi.org/10.3390/geosciences10090373.
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Knowledge about extreme groundwater levels is needed to avoid structural or environmental damage by groundwater flooding. Typically, distributions of extreme groundwater levels are generated by interpolation between results derived from local extreme value analysis at groundwater observation wells. As an alternative methodology, we propose to apply the Gumbel distribution to groundwater level time series, which are computed by a groundwater flow model. In the approach, model-based and observation-based extreme groundwater values are compared at every observation well using the model simulation period and the longest available observation period to calculate correction values that are regionalized over the model area. We demonstrate the applicability of the approach at the Südliches Wiener Becken (SWB) aquifer south of Vienna, where a groundwater flow model between 1993 to 2017 is available to compute the distribution of the groundwater levels with a hundred year return period (GLsWHYRP). We could show that the resulting GLsWHYRP are generally increased in regions of groundwater recharge and decreased in regions of groundwater discharge. The developed approach can also be used to assess the impact of changing boundary conditions on groundwater level and extreme highs and lows based on corresponding model scenarios.
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Lei, Xinbo, Xiuhua Zheng, Chenyang Duan, Jianhong Ye und Kang Liu. „Three-Dimensional Numerical Simulation of Geothermal Field of Buried Pipe Group Coupled with Heat and Permeable Groundwater“. Energies 12, Nr. 19 (27.09.2019): 3698. http://dx.doi.org/10.3390/en12193698.
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The flow of groundwater and the interaction of buried pipe groups will affect the heat transfer efficiency and the distribution of the ground temperature field, thus affecting the design and operation of ground source heat pumps. Three-dimensional numerical simulation is an effective method to study the buried pipe heat exchanger and ground temperature distribution. According to the heat transfer control equation of non-isothermal pipe flow and porous media, combined with the influence of permeable groundwater and tube group, a heat-transfer coupled heat transfer model of the buried pipe group was established, and the accuracy of the model was verified by the sandbox test and on-site thermal response test. By processing the layout of the buried pipe in the borehole to reduce the number of meshes and improve the meshing quality, a three-dimensional numerical model of the buried pipe cluster at the site scale was established. Additionally, the ground temperature field under the thermal-osmotic coupling of the buried pipe group during groundwater flow was simulated and the influence of the head difference and hydraulic conductivity on the temperature field around the buried pipe group was calculated and analyzed. The results showed that the research on the influence of the tube group and permeable groundwater on the heat transfer and ground temperature field of a buried pipe simulated by COMSOL software is an advanced method.
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Zhao, Ying Wang, Xue Yuan Li, Shi Lei Chen und Kai Bian. „Groundwater Flow Field Analysis and 3D Visualization System“. Advanced Materials Research 1073-1076 (Dezember 2014): 1664–68. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1664.
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According to the low accuracy of velocity filed in current software, we develop a new system to analyze and visualize the 3D groundwater flow field. We employ the most advanced algorithm to deal with the data form groundwater simulation. The system could compute the flux across arbitrary face and the velocity of arbitrary point in the research domain. The system is debugged in Microsoft Visual Studio. The interactive interface is developed in .Net and the visualization tool is OpenGL. The application shows that the system is robust.
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Ryu, Han-Sun, Jinah Moon, Heejung Kim und Jin-Yong Lee. „Modeling and Parametric Simulation of Microplastic Transport in Groundwater Environments“. Applied Sciences 11, Nr. 16 (04.08.2021): 7189. http://dx.doi.org/10.3390/app11167189.
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Efforts to reduce the toxic effects of microplastics (MPs) on the environment have increased globally in recent years. However, the existing models used for the simulation of contaminant transport in groundwater are meant for dissolved substances, which is not suitable for studying MPs. Therefore, in this study, the transport of MPs in a saturated porous medium was modeled by establishing governing equations. Simulations were performed using the finite element method to examine the effects of the parameters of the governing equations on the transport of MPs. The results suggest that it is necessary to reduce the diffusivity of MPs and increase the water flow velocity, porosity, and first-order attachment coefficient to effectively contain this environmental hazard. From the simulation results, it can be derived that a combination of low diffusivity, fast water flow velocity, and high soil porosity may reduce the amount of MPs that are leaked into groundwater environments. The modeling and simulations performed in this study provide a clear understanding of the transport phenomena of MPs with applications in combating water pollution.
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Fischer, T., D. Naumov, S. Sattler, O. Kolditz und M. Walther. „GO2OGS 1.0: a versatile workflow to integrate complex geological information with fault data into numerical simulation models“. Geoscientific Model Development 8, Nr. 11 (12.11.2015): 3681–94. http://dx.doi.org/10.5194/gmd-8-3681-2015.
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Abstract. We offer a versatile workflow to convert geological models built with the ParadigmTM GOCAD© (Geological Object Computer Aided Design) software into the open-source VTU (Visualization Toolkit unstructured grid) format for usage in numerical simulation models. Tackling relevant scientific questions or engineering tasks often involves multidisciplinary approaches. Conversion workflows are needed as a way of communication between the diverse tools of the various disciplines. Our approach offers an open-source, platform-independent, robust, and comprehensible method that is potentially useful for a multitude of environmental studies. With two application examples in the Thuringian Syncline, we show how a heterogeneous geological GOCAD model including multiple layers and faults can be used for numerical groundwater flow modeling, in our case employing the OpenGeoSys open-source numerical toolbox for groundwater flow simulations. The presented workflow offers the chance to incorporate increasingly detailed data, utilizing the growing availability of computational power to simulate numerical models.
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Wu, Yue, Yan-Zhi Li, Wei-Guo Qiao, Zhen-Wang Fan, Shuai Zhang, Kui Chen und Lei Zhang. „Water Seepage in Rocks at Micro-Scale“. Water 14, Nr. 18 (11.09.2022): 2827. http://dx.doi.org/10.3390/w14182827.
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To complete groundwater diversion, the complex flow law of groundwater in rocks must be investigated so that groundwater diversion can be improved. This research uses the computer finite element method (FEM), CT scanning calculation method, Avizo method, and digital core technology combined with the Fluent calculation method (FCM) to reconstruct rocks with microscopic pore structures on a computer. The numerical simulation results under different conditions show that: the total pressure change gradually decreases under different pressure gradients. In a seepage channel, the seepage path does not change with the change in seepage pressure, and the seepage velocity is the largest in the center of the pore. The longer the seepage path is, the greater the decrease in seepage velocity. Different seepage directions have similar seepage laws. The research results provide effective guidance for the project to control groundwater.
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Xueya, Lin, und Yang Yuesuo. „The Optimization of Ground Water Supply System in Shi Jiazhuang City, China“. Water Science and Technology 24, Nr. 11 (01.12.1991): 71–76. http://dx.doi.org/10.2166/wst.1991.0338.
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This paper established a response function of groundwater level using the principle of superposition formed a response matrix which combined the simulation model of groundwater flow system and the optimization model of groundwater supply system. The calculation was carried out by micro-computer. Two methods were used to determine the unit pulse value so as to calculate more accurate response coefficients. Based on the hydrogeologic conceptual model of the study area, a management model for optimization of groundwater supply system was established under the conditions of not only meeting the increasingly growing need of water supply but also controlling or eliminating the various hazards caused by overpumping of groundwater, and a practical, feasible and comprehensive decision making plan was also put forward for Shi Jiazhuang city.
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Pongritsakda, Thatthep, Kengo Nakamura, Jiajie Wang, Noriaki Watanabe und Takeshi Komai. „Prediction and Remediation of Groundwater Pollution in a Dynamic and Complex Hydrologic Environment of an Illegal Waste Dumping Site“. Applied Sciences 11, Nr. 19 (04.10.2021): 9229. http://dx.doi.org/10.3390/app11199229.
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The characteristics of groundwater pollution caused by illegal waste dumping and methods for predicting and remediating it are still poorly understood. Serious 1,4-dioxane groundwater pollution—which has multiple sources—has been occurring at an illegal waste dumping site in the Tohoku region of Japan. So far, anti-pollution countermeasures have been taken including the installation of an impermeable wall and the excavation of soils and waste as well as the monitoring of contamination concentrations. The objective of this numerical study was to clarify the possibility of predicting pollutant transport in such dynamic and complex hydrologic environments, and to investigate the characteristics of pollutant transport under both naturally occurring and artificially induced groundwater flow (i.e., pumping for remediation). We first tried to reproduce the changes in 1,4-dioxane concentrations in groundwater observed in monitoring wells using a quasi-3D flow and transport simulation considering the multiple sources and spatiotemporal changes in hydrologic conditions. Consequently, we were able to reproduce the long-term trends of concentration changes in each monitoring well. With the predicted pollutant distribution, we conducted simulations for remediation such as pollutant removal using pumping wells. The results of the prediction and remediation simulations revealed the highly complex nature of 1,4-dioxane transport in the dumping site under both naturally occurring and artificially induced groundwater flows. The present study suggests possibilities for the prediction and remediation of pollution at illegal waste dumping sites, but further extensive studies are encouraged for better prediction and remediation.
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Booij, M., A. Leijnse, S. Haldorsen, M. Heim und H. Rueslåtten. „Subpermafrost Groundwater Modelling in Ny-Ålesund, Svalbard“. Hydrology Research 29, Nr. 4-5 (01.08.1998): 385–96. http://dx.doi.org/10.2166/nh.1998.0030.
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Svalbard is a high arctic archipelago where the permafrost thickness is 150-450 m and almost continuous in ice-free areas. The model work was carried out in Ny-Ålesund, where the subpermafrost aquifers are recharged by water from the bottom of the Vestre Lovénbreen glacier. One main discharge spring is found at the entrance of an old coal mine. The computer code SUTRA has been used to simulate two-dimensional fluid movement and energy transport in the ground under steady state conditions. For the simulation, a cross section with unit thickness parallel to groundwater flow has been chosen. With the resulting output of SUTRA, contour maps of the pressure, hydraulic head, temperature and velocity have been made. Residence times for different situations have been determined to be15 years as a minimum. In general there is a good agreement between the physical reality and the simulation results.
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Triatmojo, Pramudita, und Mas Agus Mardyanto. „Forward Problems Solving of Groundwater Flow using Stochastic Groundwater Vistas Method“. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands 10, Nr. 2 (01.10.2021): 160–69. http://dx.doi.org/10.36706/jlso.10.2.2021.525.
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In the forward problems, the hydraulic head value can be found by knowing the value of the groundwater parameter. Parameters of groundwater such as hydraulic conductivity, vary over space due to the variation of aquifer properties. Consequently, it is difficult or almost impossible to treat these kinds of variability by a deterministic approach because there is no exact value to be used as input for a parameter. The objective of this research was to obtain a mathematical model of groundwater flow made with the Groundwater Vistas Program that is in accordance with the physical model. Mathematical modeling of groundwater flow using the Groundwater Vistas Program with a stochastic approach and Monte Carlo simulation method where the input data (hydraulic conductivity, hydraulic head) is obtained from the physical model. Results showed that the sum of squares value from the scatter plot diagram of all realization points had a very small value (close to or even zero). The residual mean diagram showed the error value of all realizations had a very low value close to zero. The calculated head value (computed) compared with the results of the observation had a fairly small difference value (ranging from 0.0006−0.009 m). These results were considered quite good because in modeling it is impossible to get modeling results that are exactly the same as those being modeled. The results show that Groundwater Vistas can be used for modeling with very small errors and it can estimate values of hydraulic heads quite well.
14
Akram, Sedki. „Improved Flower Pollination Algorithm for Optimal Groundwater Management“. International Journal of Computational Intelligence and Applications 19, Nr. 03 (05.08.2020): 2050022. http://dx.doi.org/10.1142/s1469026820500224.
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Groundwater management problems are typically of a large-scale nature, involving complex nonlinear objective functions and constraints, which are commonly evaluated through the use of numerical simulation models. Given these complexities, metaheuristic optimization algorithms have recently become popular choice for solving such complex problems which are difficult to solve by traditional methods. However, the practical applications of metaheuristics are severely challenged by the requirement of large number of function evaluations to achieve convergence. To overcome this shortcoming, many new metaheuristics and different variants of existing ones have been proposed in recent years. In this study, a recently developed algorithm called flower pollination algorithm (FPA) is investigated for optimal groundwater management. The FPA is improved, combined with the widely used groundwater flow simulation model MODFLOW, and applied to solve two groundwater management problems. The proposed algorithm, denoted as IFPA, is first tested on a hypothetical aquifer system, to minimize the total pumping to contain contaminated groundwater within a capture zone. IFPA is then applied to maximize the total annual pumping from existing wells in Rhis-Nekor unconfined coastal aquifer on the northern of Morocco. The obtained results indicate that IFPA is a promising method for solving groundwater management problems as it outperforms the standard FPA and other algorithms applied to the case studies considered, both in terms of convergence rate and solution quality.
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Hughes, J. D., C. D. Langevin und J. T. White. „MODFLOW-Based Coupled Surface Water Routing and Groundwater-Flow Simulation“. Groundwater 53, Nr. 3 (05.06.2014): 452–63. http://dx.doi.org/10.1111/gwat.12216.
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Bedekar, Vivek, Richard G. Niswonger, Kenneth Kipp, Sorab Panday und Matthew Tonkin. „Approaches to the Simulation of Unconfined Flow and Perched Groundwater Flow in MODFLOW“. Ground Water 50, Nr. 2 (02.06.2011): 187–98. http://dx.doi.org/10.1111/j.1745-6584.2011.00829.x.
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Owen, S. J., N. L. Jones und J. P. Holland. „A comprehensive modeling environment for the simulation of groundwater flow and transport“. Engineering with Computers 12, Nr. 3-4 (September 1996): 235–42. http://dx.doi.org/10.1007/bf01198737.
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Cai, Jinbang, Yue Su, Huan Shen und Yong Huang. „Simulation of Groundwater Flow in Fractured-Karst Aquifer with a Coupled Model in Maling Reservoir, China“. Applied Sciences 11, Nr. 4 (21.02.2021): 1888. http://dx.doi.org/10.3390/app11041888.
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A coupled model has been developed to simulate groundwater flow in fractured karst systems according to the complex geological and karst hydrogeological conditions of the dam site, where a 3D mathematical model based on Boussinesq equation was used to describe the movement of groundwater flow in fractured medium, and a 1D conduit model for karst medium. The model was solved with the continuous hydraulic heads at the common boundaries. The hydraulic conductivities of karst medium were determined by geometrical parameters and flux of pipes. Furthermore, the permeability parameters for fractured medium were calibrated by the measured and calculated groundwater levels. The calibrated model was employed to predict the variation of groundwater flow field and leakage from the karst pipes and underground powerhouse during the reservoir operation. The simulated results showed that the groundwater level of the powerhouse had decreased by about 2–5 m. The water level of conveyance pipeline had risen by 10–20 m, and the water level on both banks had risen by 15–25 m. The leakage of karst conduits for impervious failure was larger than that for normal seepage control. In addition, the leakage of the powerhouse was estimated to be about 1000–3000 m3/d, and the seepage control of karst pipes had little influence on the leakage of underground powerhouse.
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Tolera, Mesfin Benti, und Il-Moon Chung. „Integrated Hydrological Analysis of Little Akaki Watershed Using SWAT-MODFLOW, Ethiopia“. Applied Sciences 11, Nr. 13 (28.06.2021): 6011. http://dx.doi.org/10.3390/app11136011.
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In Ethiopia, groundwater is the main source of freshwater to support human consumption and socio-economic development. Little Akaki watershed is located in Upper Awash basin, known for its high annual rainfall and considered as the potential groundwater recharge zone. On the contrary, urbanization and industrial expansion are increasing at an alarming rate in the area. This became a concern threatening the groundwater resources’ sustainability. To address these challenges, integrated analysis of groundwater recharge and groundwater numerical simulations were made. For groundwater recharge estimation, SWAT model was used. The result indicated that recharge in the watershed mostly occurs from July to October with maximum values in August. On average, the estimated annual catchment recharge was 179 mm. For the numerical simulation and prediction of the groundwater flow system, MODFLOW 2005 was used. The model simulations indicated that the groundwater head converges towards the main river and, finally, to the outlet of the watershed. The study indicated areas of interactions between the river and groundwater. The scenario examination result reveals increasing the present pumping rate by over fifty percent (by 50%, 100%, and 200%) will surely cause visible groundwater head decline near the outlet of the watershed, and substantial river baseflow reduction. The recharge reduction scenario also indicates the huge risk of groundwater sustainability in the area.
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Serageldin, Ahmed A., Ali Radwan, Yoshitaka Sakata, Takao Katsura und Katsunori Nagano. „The Effect of Groundwater Flow on the Thermal Performance of a Novel Borehole Heat Exchanger for Ground Source Heat Pump Systems: Small Scale Experiments and Numerical Simulation“. Energies 13, Nr. 6 (18.03.2020): 1418. http://dx.doi.org/10.3390/en13061418.
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New small-scale experiments are carried out to study the effect of groundwater flow on the thermal performance of water ground heat exchangers for ground source heat pump systems. Four heat exchanger configurations are investigated; single U-tube with circular cross-section (SUC), single U-tube with an oval cross-section (SUO), single U-tube with circular cross-section and single spacer with circular cross-section (SUC + SSC) and single U-tube with an oval cross-section and single spacer with circular cross-section (SUO + SSC). The soil temperature distributions along the horizontal and vertical axis are measured and recorded simultaneously with measuring the electrical energy injected into the fluid, and the borehole wall temperature is measured as well; consequently, the borehole thermal resistance (Rb) is calculated. Moreover, two dimensional and steady-state CFD simulations are validated against the experimental measurements at the groundwater velocity of 1000 m/year with an average error of 3%. Under saturated conditions without groundwater flow effect; using a spacer with SUC decreases the Rb by 13% from 0.15 m·K/W to 0.13 m·K/W, also using a spacer with the SUO decreases the Rb by 9% from 0.11 m·K/W to 0.1 m·K/W. In addition, the oval cross-section with spacer SUO + SSC decreases the Rb by 33% compared with SUC. Under the effect of groundwater flow of 1000 m/year; Rb of the SUC, SUO, SUC + SSC and SUO + SSC cases decrease by 15.5%, 12.3%, 6.1% and 4%, respectively, compared with the saturated condition.
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Kaneko, Shohei, Akira Tomigashi, Takeshi Ishihara, Gaurav Shrestha, Mayumi Yoshioka und Youhei Uchida. „Proposal for a Method Predicting Suitable Areas for Installation of Ground-Source Heat Pump Systems Based on Response Surface Methodology“. Energies 13, Nr. 8 (11.04.2020): 1872. http://dx.doi.org/10.3390/en13081872.
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The installation potential of ground-source heat pump (GSHP) systems has been studied based on the spatial interpolation of numerical simulation results using ground heat exchanger (GHE) models. This study is the first to create an estimation formula for the heat exchange rate (HER) to obtain a solution equivalent to the numerical analysis results considering the average method when supplying three-dimensional (3D) hydrogeological information that affects the HER to a two-dimensional (2D) map. It was found that the main factors affecting the HER were groundwater flow velocity, subsurface temperature, and thermal conductivity. The response surface methodology was utilized to approximate the HER using the above-mentioned three parameters. The estimated HER showed very strong agreement with that calculated by the GHE models. The application of the estimation formula to the simulation of the 3D groundwater flow and heat transport model of the Sendai Plain (Japan) better reflects the hydrogeological information of the regional model than conventional maps. The proposed method improves the spatial resolution of maps and allows for the easy creation of the HER estimation formula.
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An, Nguyen Ngoc, Huynh Song Nhut, Tran Anh Phuong, Vu Quang Huy, Nguyen Cao Hanh, Giang Thi Phuong Thao, Pham The Trinh, Pham Viet Hoa und Nguyễn An Bình. „Groundwater simulation in Dak Lak province based on MODFLOW model and climate change scenarios“. Frontiers in Engineering and Built Environment 2, Nr. 1 (25.01.2022): 55–67. http://dx.doi.org/10.1108/febe-11-2021-0055.
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PurposeGroundwater plays a critical part in both natural and human existence. When surface water is scarce in arid climates, groundwater becomes an immensely valuable resource. Dak Lak is an area that frequently lacks water resources for everyday living and production, and the scarcity of water resources is exacerbated during the dry season. As a result, it is critical to do study and understand about groundwater to meet the region's water demand. This study aims to extend the use of the MODFLOW model for groundwater simulation and assess the overall groundwater reserves and water demand in the highland province Dak Lak.Design/methodology/approachThe MODFLOW model is used in this work to compute and analyze the flow, prospective reserves of groundwater from which to plan extraction and estimate groundwater variation in the future.FindingsThe application of the MODFLOW model to Dak Lak province demonstrates that, despite limited data, particularly drilling hole data for subterranean water research, the model's calculation results have demonstrated its reliability and great potential for use in other similar places. The use of the model in conjunction with other data extraction modules is a useful input for creating underground flow module maps for various time periods. The large impact of recharge and evaporation on groundwater supplies and water balance in the research area is demonstrated by simulations of climate change scenarios RCP4.5 and RCP8.5.Originality/valueNone of the studies has been done previously to analyze water resources of Dak Lak and the scarcity of water resources is exacerbated during the dry season. Therefore, this study will provide useful insights in the water resource management and the conservation of Dak Lak. The groundwater in Dak Lak can meet the area's water demand, according to the results obtained and water balance in the study area. However, the management of water resources and rigorous monitoring of groundwater extraction activities in the area should receive more attention.
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Cheng, Tangpei, Zeyao Mo und Jingli Shao. „Accelerating Groundwater Flow Simulation in MODFLOW Using JASMIN-Based Parallel Computing“. Groundwater 52, Nr. 2 (18.04.2013): 194–205. http://dx.doi.org/10.1111/gwat.12047.
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Kobayashi, Kenichiro, Reinhard Hinkelmann und Rainer Helmig. „Development of a simulation–optimization model for multiphase systems in the subsurface: a challenge to real-world simulation–optimization“. Journal of Hydroinformatics 10, Nr. 2 (01.03.2008): 139–52. http://dx.doi.org/10.2166/hydro.2008.013.
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The main purpose of this paper is to demonstrate the capability of a new simulation–optimization model especially tailored to investigate the optimal management strategy of a closed coal mine in the Ruhr, Germany. This paper deals with the multiphase/multicomponent flow simulation; the optimization model (simulated annealing); the mesh generation function; the coupling of them; and the use of a parallel computer. Firstly, a mesh generation function is included in the total procedure for the modelling of complex system configurations often required when the real-world problem is dealt with. The multiphase/multicomponent flow simulator can simulate not only groundwater flow and a tracer in it but also the multiphase systems (e.g. gas–water, gas–water–NAPL system). Moreover, a parallelization strategy for the optimization procedure is proposed and implemented to overcome the enormous CPU time problem always tagged to real-world simulation–optimizations. This strategy succeeded in enhancing the efficiency of the overall procedure almost linearly by the number of the processors in a parallel computer. This model is then applied to study how to install the passive extraction wells for controlling the migration of methane continuously desorbed from coal seams inside the closed coal mine in the Ruhr, Germany. The general rule proposed as the result of the application is rather simple although it is considered very useful in many practices of coal mining operations. This paper briefly outlines the overall procedure.
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Głogowski, Arkadiusz, und Mieczysław Chalfen. „Analysis of the effectiveness of the systems protecting against the impact of water damming in the river on the increase of groundwater level on the example of the Malczyce dam“. ITM Web of Conferences 23 (2018): 00011. http://dx.doi.org/10.1051/itmconf/20182300011.
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The aim of the article is to determine to what extent individual elements of the project protecting the village of Rzeczyca and adjacent areas against flooding after the planned damming up of water in the Odra on the Malczyce dam. The assessment of the impact of damming on the nearby towns was made using a mathematical model based on a two-dimensional and non-stationary version of the Boussinesq equation and the finite element method (FEM). In the simulations, the proprietary FIZ software was used for calculating water flow and chemical pollution in a porous medium. Four computer simulations were carried out, modelling the flow of groundwater in the left-bank Odra valley. The first simulation was run in pre-towering conditions, the second one included water damming without additional safeguards, the third one with a watertight membrane and the fourth one with a membrane and a drainage channel.
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Rudolph, D. L., und E. A. Sudicky. „Simulation of groundwater flow in complex multiaquifer systems: Performance of a quasi three-dimensional technique in the steady-state case“. Canadian Geotechnical Journal 27, Nr. 5 (01.10.1990): 590–600. http://dx.doi.org/10.1139/t90-074.
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The ability of the classical quasi three-dimensional formulation to describe steady-state groundwater flow problems in complex multiaquifer environments is examined. In the present formulation, discontinuities in the aquifer and aquitard units can be accommodated along with partial or complete aquifer dewatering and confined or unconfined flow conditions. Some of the main assumptions underlying classical quasi three-dimensional schemes are scrutinized, including the requirement of a two orders of magnitude permeability contrast between aquifers and aquitards. Performance of the numerical scheme is studied through a series of test problems by comparing with results obtained from a conventional finite element model. A high degree of accuracy and flexibility is achieved with the extended quasi three-dimensional technique, yet the numerical efficiency inherent in the classical formulation is maintained. By dividing an aquifer into a series of horizontal sublayers, vertical resolution of the flow field can be achieved without resorting to a numerically intensive fully three-dimensional scheme. Because it is possible to compute a three-dimensional representation of the hydraulic head distribution in individual aquifers with the quasi three-dimensional formulation, even in the absence of layers of contrasting hydraulic conductivity, the technique provides a viable alternative to the much more complex fully three-dimensional schemes for a wide variety of groundwater flow problems. Key words: groundwater flow, multiaquifer, complex stratigraphy, numerical analysis, quasi three-dimensional, steady state.
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Hanasaki, Naota, Sayaka Yoshikawa, Yadu Pokhrel und Shinjiro Kanae. „A global hydrological simulation to specify the sources of water used by humans“. Hydrology and Earth System Sciences 22, Nr. 1 (29.01.2018): 789–817. http://dx.doi.org/10.5194/hess-22-789-2018.
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Abstract. Humans abstract water from various sources to sustain their livelihood and society. Some global hydrological models (GHMs) include explicit schemes of human water abstraction, but the representation and performance of these schemes remain limited. We substantially enhanced the water abstraction schemes of the H08 GHM. This enabled us to estimate water abstraction from six major water sources, namely, river flow regulated by global reservoirs (i.e., reservoirs regulating the flow of the world's major rivers), aqueduct water transfer, local reservoirs, seawater desalination, renewable groundwater, and nonrenewable groundwater. In its standard setup, the model covers the whole globe at a spatial resolution of 0.5° × 0.5°, and the calculation interval is 1 day. All the interactions were simulated in a single computer program, and all water fluxes and storage were strictly traceable at any place and time during the simulation period. A global hydrological simulation was conducted to validate the performance of the model for the period of 1979–2013 (land use was fixed for the year 2000). The simulated water fluxes for water abstraction were validated against those reported in earlier publications and showed a reasonable agreement at the global and country level. The simulated monthly river discharge and terrestrial water storage (TWS) for six of the world's most significantly human-affected river basins were compared with gauge observations and the data derived from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. It is found that the simulation including the newly added schemes outperformed the simulation without human activities. The simulated results indicated that, in 2000, of the 3628±75 km3 yr−1 global freshwater requirement, 2839±50 km3 yr−1 was taken from surface water and 789±30 km3 yr−1 from groundwater. Streamflow, aqueduct water transfer, local reservoirs, and seawater desalination accounted for 1786±23, 199±10, 106±5, and 1.8±0 km3 yr−1 of the surface water, respectively. The remaining 747±45 km3 yr−1 freshwater requirement was unmet, or surface water was not available when and where it was needed in our simulation. Renewable and nonrenewable groundwater accounted for 607±11 and 182±26 km3 yr−1 of the groundwater total, respectively. Each source differed in its renewability, economic costs for development, and environmental consequences of usage. The model is useful for performing global water resource assessments by considering the aspects of sustainability, economy, and environment.
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Budinski, Ljubomir, Julius Fabian und Matija Stipic. „Modeling groundwater flow by lattice Boltzmann method in curvilinear coordinates“. International Journal of Modern Physics C 26, Nr. 02 (Februar 2015): 1550013. http://dx.doi.org/10.1142/s0129183115500138.
Annotation:
In order to promote the use of the lattice Boltzmann method (LBM) for the simulation of isotropic groundwater flow in a confined aquifer with arbitrary geometry, Poisson's equation was transformed into a curvilinear coordinate system. With the metric function between the physical and the computational domain established, Poisson's equation written in Cartesian coordinates was transformed in curvilinear coordinates. Following, the appropriate equilibrium function for the D2Q9 square lattice has been defined. The resulting curvilinear formulation of the LBM for groundwater flow is capable of modeling flow in domains of complex geometry with the opportunity of local refining/coarsening of the computational mesh corresponding to the complexity of the flow pattern and the required accuracy. Since the proposed form of the LBM uses the transformed equation of flow implemented in the equilibrium function, finding a solution does not require supplementary procedures along the curvilinear boundaries, nor in the zones requiring mesh density adjustments. Thus, the basic concept of the LBM is completely maintained. The improvement of the proposed LBM over the previously published classical methods is completely verified by three examples with analytical solutions. The results demonstrate the advantages of the proposed curvilinear LBM in modeling groundwater flow in complex flow domains.
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Bultreys, T., S. Van Offenwert, W. Goethals, M. N. Boone, J. Aelterman und V. Cnudde. „X-ray tomographic micro-particle velocimetry in porous media“. Physics of Fluids 34, Nr. 4 (April 2022): 042008. http://dx.doi.org/10.1063/5.0088000.
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Fluid flow through intricate confining geometries often exhibits complex behaviors, certainly in porous materials, e.g., in groundwater flows or the operation of filtration devices and porous catalysts. However, it has remained extremely challenging to measure 3D flow fields in such micrometer-scale geometries. Here, we introduce a new 3D velocimetry approach for optically opaque porous materials, based on time-resolved x-ray micro-computed tomography (CT). We imaged the movement of x-ray tracing micro-particles in creeping flows through the pores of a sandpack and a porous filter, using laboratory-based CT at frame rates of tens of seconds and voxel sizes of 12 μm. For both experiments, fully three-dimensional velocity fields were determined based on thousands of individual particle trajectories, showing a good match to computational fluid dynamics simulations. Error analysis was performed by investigating a realistic simulation of the experiments. The method has the potential to measure complex, unsteady 3D flows in porous media and other intricate microscopic geometries. This could cause a breakthrough in the study of fluid dynamics in a range of scientific and industrial application fields.
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Szymkiewicz, Adam, Anna Gumuła-Kawęcka, Dawid Potrykus, Beata Jaworska-Szulc, Małgorzata Pruszkowska-Caceres und Wioletta Gorczewska-Langner. „Estimation of Conservative Contaminant Travel Time through Vadose Zone Based on Transient and Steady Flow Approaches“. Water 10, Nr. 10 (10.10.2018): 1417. http://dx.doi.org/10.3390/w10101417.
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Estimation of contaminant travel time through the vadose zone is needed for assessing groundwater vulnerability to pollution, planning monitoring and remediation activities or predicting the effect of land use change or climate change on groundwater quality. The travel time can be obtained from numerical simulations of transient flow and transport in the unsaturated soil profile, which typically require a large amount of data and considerable computational effort. Alternatively, one can use simpler analytical methods based on the assumptions of steady water flow and purely advective transport. In this study, we compared travel times obtained with transient and steady-state approaches for several scenarios. Transient simulations were carried out using the HYDRUS-1D computer program for two types of homogeneous soil profiles (sand and clay loam), two types of land cover (bare soil and grass) and two values of dispersion constant. It was shown that the presence of root zone and the dispersion constant significantly affect the results. We also computed the travel times using six simplified methods proposed in the literature. None of these methods was in good agreement with transient simulations for all scenarios and the discrepancies were particularly large for the case of clay loam with grass cover.
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Maier, Robert S., D. M. Kroll, H. Ted Davis und Robert S. Bernard. „Pore-Scale Flow and Dispersion“. International Journal of Modern Physics C 09, Nr. 08 (Dezember 1998): 1523–33. http://dx.doi.org/10.1142/s0129183198001370.
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Pore-scale simulations of fluid flow and mass transport offer a direct means to reproduce and verify laboratory measurements in porous media. We have compared lattice-Boltzmann (LB) flow simulations with the results of NMR spectroscopy from several published flow experiments. Although there is qualitative agreement, the differences highlight numerical and experimental issues, including the rate of spatial convergence, and the effect of signal attenuation near solid surfaces. For the range of Reynolds numbers relevant to groundwater investigations, the normalized distribution of fluid velocities in random sphere packings collapse onto a single curve, when scaled with the mean velocity. Random-walk particle simulations in the LB flow fields have also been performed to study the dispersion of an ideal tracer. These simulations show an encouraging degree of quantitative agreement with published NMR measurements of hydrodynamic and molecular dispersion, and the simulated dispersivities scale in accordance with published experimental and theoretical results for the Peclet number rangek 1 ≤ Pe ≤1500. Experience with the random-walk method indicates that the mean properties of conservative transport, such as the first and second moments of the particle displacement distribution, can be estimated with a number of particles comparable to the spatial discretization of the velocity field. However, the accurate approximation of local concentrations, at a resolution comparable to that of the velocity field, requires significantly more particles. This requirement presents a significant computational burden and hence a numerical challenge to the simulation of non-conservative transport processes.
32
Yang, Zhiquan, Dan Zhang, Chaoyue Li, Zhiwei Zhang, Yingyan Zhu, Yi Yang, Na He et al. „Column Penetration and Diffusion Mechanism of Bingham Fluid Considering Displacement Effect“. Applied Sciences 12, Nr. 11 (25.05.2022): 5362. http://dx.doi.org/10.3390/app12115362.
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The diffusion progress of grout is hindered by groundwater, which means the diffusion distance cannot reach the designed values required in engineering for water plugging or reinforcement. In this study, based on the generalized Darcy’s law and the continuity equation of steady column penetration, a column diffusion mechanism for Bingham fluid, considering the displacement effect of grout on groundwater, is proposed. This diffusion mechanism is then validated by the penetration grouting experiments that have been previously performed. The influences of the grouting pressure, groundwater pressure, water–cement ratio and penetration coefficient of porous media on the diffusion radius are analyzed. Based on the Comsol Multiphysics platform, a three-dimensional numerical simulation program for this mechanism is developed using computer programming technology. Numerical simulations of the penetration and diffusion morphology of Bingham cement grout in porous media are then carried out. The results show that the theoretical calculation values of diffusion radius obtained from this mechanism are closer to the experimental values than those obtained from the column penetration grouting theory of Bingham fluid, without considering the displacement effect. The results of this study can provide theoretical support for practical grouting engineering.
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Ashby, S. F., W. J. Bosl, R. D. Falgout, S. G. Smith, A. F. B. Tompson und T. J. Williams. „A Numerical Simulation of Groundwater Flow and Contaminant Transport on the CRAY T3D and C90 Supercomputers“. International Journal of High Performance Computing Applications 13, Nr. 1 (März 1999): 80–93. http://dx.doi.org/10.1177/109434209901300105.
34
Phoban, Harutus, Uma Seeboonruang und Prateep Lueprasert. „Numerical Modeling of Single Pile Behaviors Due to Groundwater Level Rising“. Applied Sciences 11, Nr. 13 (22.06.2021): 5782. http://dx.doi.org/10.3390/app11135782.
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Behaviors of the pile foundation due to groundwater level rising were analyzed by a series two-dimensional finite element analyses with fully coupled flow-deformation analysis. The different numerical models of single bore pile depth and diameter in Bangkok subsoil were represented with the parametric study. The pile–soil movement due to groundwater levels rising between numerical simulation and a previous experiment of the centrifuge test as the same condition are in good agreement. With rising groundwater level, the reduction of pile capacity can be evidently performed by the increase of pile settlement relative to soil surface. Moreover, the development of the plastic point captured by the finite element analysis revealed the mechanism behind the reduction of pile capacity. In this study, the evaluation of pile stability due to groundwater level rising for preliminary guidelines to protect existing structures are proposed.
35
Liu, Sida, Yangxiao Zhou, Mingzhao Xie, Michael E. McCalin und Xu-Sheng Wang. „Comparative Assessment of Methods for Coupling Regional and Local Groundwater Flow Models: A Case Study in the Beijing Plain, China“. Water 13, Nr. 16 (16.08.2021): 2229. http://dx.doi.org/10.3390/w13162229.
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A coupled regional and local model is required when groundwater flow and solute transport are to be simulated in local areas of interest with a finer grid while regional aquifer boundary and major stresses should be retained with a coarser grid. The coupled model should also maintain interactions between the regional and local flow systems. In the Beijing Plain (China), assessment of managed aquifer recharge (MAR), groundwater pollution caused by rivers, capture zone of well fields, and land subsidence at the cone of depression requires a coupled regional and local model. This study evaluates three methods for coupling regional and local flow models for simulating MAR in the Chaobai River catchment in the Beijing Plain. These methods are the conventional grid refinement (CGR) method, the local grid refinement (LGR) method and the unstructured grid (USG) method. The assessment included the comparison of the complexity of the coupled model construction, the goodness of fit of the computed and observed groundwater heads, the consistency of regional and local groundwater budgets, and the capture zone of a well filed influenced by the MAR site. The results indicated that the CGR method based on MODFLOW-2005 is the easiest to implement the coupled model, capable of reproducing regional and local groundwater heads and budget, and already coupled with density and viscosity dependent model codes for transport simulation. However, the CGR method inherits shortcomings of finite difference grids to create multiple local models with inefficient computing efforts. The USG method based on MODFLOW-USG has the advantage of creating multi-scale models and is flexible to simulate rivers, wells, irregular boundaries, heterogeneities and the MAR site. However, it is more difficult to construct the coupled models with the unstructured grids, therefore, a good graphic user interface is necessary for efficient model construction. The LGR method based on MODFLOW-LGR can be used to create multiple local models in uniform aquifer systems. So far, little effort has been devoted to upgrade the LGR method for complex aquifer structures and develop the coupled transport models.
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Wang, Xiaopu, Lianjie Hou, Tianhao He, Zhenhan Diao, Chuanjin Yao, Tao Long und Ling Fan. „Numerical Simulation of the Enrichment of Chemotactic Bacteria in Oil-Water Two-Phase Transfer Fields of Heterogeneous Porous Media“. Applied Sciences 12, Nr. 10 (21.05.2022): 5215. http://dx.doi.org/10.3390/app12105215.
Annotation:
Oil pollution in soil-groundwater systems is difficult to remove, and a large amount of residual oil is trapped in the low permeable layer of the heterogeneous aquifer. Aromatic hydrocarbons in oil have high toxicity and low solubility in water, which are harmful to the ecological environment. Chemotactic degrading bacteria can perceive the concentration gradient of non-aqueous phase liquid (NAPL) pollutants in the groundwater environment, and enrich and proliferate around the pollutants, thus achieving a more efficient and thorough remediation effect. However, the existing theoretical models are relatively simple. The physical fields of oil–water two-phase flow and oil-phase solute convection and diffusion in water are not coupled, which further restricts the accuracy of studies on bacterial chemotaxis to NAPL. In this study, geometric models based on the actual microfluidic experimental study were constructed. Based on the phase field model, diffusion convection equation and chemotaxis velocity equation, the effects of heterogeneity of porous media, wall wettability and groundwater flow rate on the residual oil and the concentration distribution of chemotaxis bacteria were studied. Under all of the simulation conditions, the residual oil in the high permeable area was significantly lower than that in the low permeable area, and the wall hydrophilicity enhanced the water flooding effect. Chemotactic bacteria could react to the concentration gradient of pollutants dissolved into water in the oil phase, and enrich near the oil–water interface with high concentration of NAPL, and the density of chemotactic bacteria at the oil–water interface can be up to 1.8–2 times higher than that in the water phase at flow rates from 1.13 to 6.78 m/d.
37
Refsgaard, Anders, Steen Christensen und Jan Reffstrup. „Finite Element Analysis of Controlled Saltwater Intrusion in Heterogeneous Reservoirs“. Hydrology Research 20, Nr. 1 (01.02.1989): 25–42. http://dx.doi.org/10.2166/nh.1989.0003.
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Environmental cleaning operations in coastal areas by pumping are complicated by the presence of both fresh water and salt water. The density difference makes the flow conditions very complicated to predict especially if the situation is further complicated by highly heterogeneous formations. The present paper gives results from a computer simulation of saltwater movements during pumping in a heterogeneous coastal reservoir. The example problem discussed in the paper is based on data from a polluted area in the north west of Denmark. A chemical plant situated on a small peninsular has caused serious groundwater pollution. Several measures have been taken to contain the pollution including draining and extra pumping.
38
Rabemaharitra, Tahirinandraina Prudence, Yanhong Zou, Zhuowei Yi, Yong He und Umair Khan. „Optimized Pilot Point Emplacement Based Groundwater Flow Calibration Method for Heterogeneous Small-Scale Area“. Applied Sciences 12, Nr. 9 (06.05.2022): 4648. http://dx.doi.org/10.3390/app12094648.
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Groundwater flow modeling in a small-scale area requires practical techniques to obtain high accuracy results. The effectiveness of the model calibration is the most challenging for simulating the hydraulic head. In pursuit of this, we proposed an optimized groundwater flow calibration method based on the pilot point emplacement technique for a 3D small-scale area in this work. Subsequently, two emplacement structures were tested during the experimentation, the regular pilot point placement, and the middle head measurement down gradient (MHMDG) placement with two different densities. The parameter estimation (PEST) numerical code applying the kriging interpolation was used to estimate the hydraulic conductivity field by MODFLOW. Moreover, geological SGrid models were chosen for the conceptual model. Thirty-seven observation wells were used for experimental simulations to test the proposed method in a heterogeneous confined aquifer. The result shows that the small-scale modeling was complicated, and the studying area presented a significant heterogeneity in horizontal hydraulic conductivity. The middle head measurement down gradient (MHMDG) pilot point case with the larger density gave the best R-squared 0.901 and minimum residual error of 0.0053 m compared to 0.880 and 0.078 m, respectively, for the regular placement. The calibration accuracy depended on the frequency and the emplacement of the pilot point. Therefore, the initial value should be technically selected to minimize the computation burden. The proposed techniques help to improve the groundwater flow model calibration based on the pilot point methodology for groundwater resources management.
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Pasetto, Damiano, Alberto Guadagnini und Mario Putti. „A reduced-order model for Monte Carlo simulations of stochastic groundwater flow“. Computational Geosciences 18, Nr. 2 (19.12.2013): 157–69. http://dx.doi.org/10.1007/s10596-013-9389-4.
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Timaniya, Aman, und Nayankumar Soni. „“Modeling of Saline Water Intrusion using MODFLOW in Una Coastal Aquifer of Gujarat, India.”“. International Journal for Research in Applied Science and Engineering Technology 10, Nr. 5 (31.05.2022): 634–40. http://dx.doi.org/10.22214/ijraset.2022.42309.
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Abstract: Groundwater is the most valuable and extensively dispersed resource on the planet, and unlike any other mineral resource, it is replenished annually by meteoric precipitation. The present study would include simulation and modelling of the problem of seawater intrusion in the Una coastal area of Gujarat. The interrelationships of two miscible fluids in porous media have been widely explored both theoretically and experimentally. Because of the extreme salinity, many agricultural wells are no longer used. This high salinity is a sign of a process known as saltwater intrusion, which occurs mostly in coastal aquifers due to excessive pumping. Modelling software has also been utilized to analyze the behavior of groundwater flow models. Numerical models may simulate diverse groundwater scenarios and link them to groundwater management. To simulate seawater intrusion, MODFLOW-2005, a grid-based variable density-dependent flow model, is used. Water balance research reveals that rainwater recharge is the aquifer's primary input. To compute the water level in the area and estimate the position of the seawater intrusion barrier, the saltwater intrusion phenomena were simulated using the MODFLOW software combined with the SWI2 package. The model was used to visualize the salinity levels of the coastal aquifer's groundwater and their fluctuation over time and space from May 2004 to October 2014. The model was developed for a 10-year stress period with 100-time steps, which included a 5-year steady state and 5 years transient state stress period using the previous 10 years of pre-monsoon and postmonsoon data. This research would assist to describe Pumping's impact on groundwater levels and seawater intrusion was studied. Keywords: MODFLOW, Saltwater Intrusion, Modelling, Numerical Model, Coastal aquifer
41
Al-Barwani, H. H., M. Al-Lawatia, E. Balakrishnan und A. Purnama. „Modeling Flow and Transport in Unsaturated Porous Media: A Review“. Sultan Qaboos University Journal for Science [SQUJS] 5 (01.12.2000): 265. http://dx.doi.org/10.24200/squjs.vol5iss0pp265-280.
Annotation:
Underground water is a vital natural resource and every effort should be made to understand ways and means of efficiently using and managing it. The unsaturated zone, bounded at its top by the land surface and below by the water table, is the region through which water, together with pollutant carried by the water, infiltrates to reach the groundwater. Therefore, various processes occurring within the unsaturated zone play a major role in determining both the quality and quantity of water recharging into the groundwater. Classical methods of predicting water flow and contaminant transport processes in unsaturated porous media are generally inadequate when applied to natural soils under field conditions, due to the occurrence of macropores, structured elements and spatial variability of soil properties. Contaminant transport models also require the simultaneous solution of the unsaturated flow and transport equations. For applications to field conditions, numerical solutions and computer simulations based on numerical models have been increasingly used. Advances and progress in modeling water flow and contaminant transport in the unsaturated zones are reviewed, and specific research areas in need of future investigation especially relevant to Oman are outlined.
42
Wu, Yue, Wei-Guo Qiao, Yan-Zhi Li, Zhen-Wang Fan, Shuai Zhang, Lei Zhang und Xiao-Li Zhang. „Seepage of Groundwater in an Underground Fractured Rock Mass and Its Sustainable Engineering Application“. Applied Sciences 12, Nr. 16 (17.08.2022): 8221. http://dx.doi.org/10.3390/app12168221.
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Due to the existence of tiny cracks in rock, underground engineering has begun to consider how to divert a large amount of groundwater. To divert groundwater more effectively, it is necessary to master the seepage characteristics of fluids in the micropores of rocks. Based on rock samples obtained from an underground engineering site, this paper analyzes the microscopic pore structure of the rock through a combination of laboratory tests and numerical simulations and inputs this information into a computer model. The fluid seepage state in the rock under different conditions is simulated in the computer model, and parameters such as the fluid seepage velocity in the rock are obtained. Afterwards, it has been verified by engineering practice that the smallest remaining water inflow can reach 0.06‰. The results of this paper can effectively guide the discharge of groundwater to better manage water resources, greatly reduce the pollution of groundwater in construction and production environments, and reduce the pollution caused by grouting projects. Furthermore, the cleanliness and safety of underground engineering construction and production could be ensured.
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Šoltész, Andrej, Dana Baroková, Zinaw Dingetu Shenga und Michaela Červeňanská. „Hydraulic Assessment of the Impacts of Gate Realization on Groundwater Regime“. Pollack Periodica 15, Nr. 3 (07.11.2020): 162–71. http://dx.doi.org/10.1556/606.2020.15.3.16.
Annotation:
Presented paper deals with the hydraulic assessment of groundwater flow in the area affected by the realization of the hydraulic gate on the Klátov branch and in the adjacent territory of a dike, which is located on the right-side of Little Danube. This hydraulic assessment is part of the project of the Slovak Water Management Enterprise, which also aims to increase the height and seal the dike on the right-side of the Little Danube. Generally, the project is divided into three phases (Phase I, II and III) to implement different technical measures to protect the area from flooding. The assumption for the execution of the technical measures of the mentioned three project phases is a continuous flood protection of part of the Žitný ostrov area around the Little Danube and the Klátov River branch in the reach from Kolárovo to Jahodná town. Therefore, a 3D mathematical model was created to simulate groundwater flow by changing boundary conditions of surface water flow during flood periods.
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Nyende, Jacob, Isaac Enyogoi, John Mango und Henry Kasumba. „Numerical Simulation of a Two-Dimensional Groundwater Pollute Transport Problem Using Incompressible Steady-State Navier-Stokes Equations and Diffusion-Convection Equations“. Modelling and Simulation in Engineering 2022 (12.04.2022): 1–20. http://dx.doi.org/10.1155/2022/7419502.
Annotation:
Most of the real contaminant problems are defined domains that are geometrically complex and can have different boundary conditions in different areas. Therefore, it is usually difficult to find a solution analytically, so we use the approximate method to generate an approximate function. One answer to this problem is the finite element approach (FEM). This study presents a partial differential equation (PDE) simulation system that uses numerical techniques for the distribution of pollutant concentrations in groundwater in space and time. The movement of the liquid is described by the incompressible steady-state Navier-Strokes equation, while the transport of pollutants is described by the diffusion-convention equation. The variation formulation that forms the basis of FEM and MATLAB is discussed along with the selection of the abstract approximation space and the welfare of the weak formulation. The motivation for this study comes from a specific and considered water body with the discharge of factory effluents on the ground that ends up reducing the quality of groundwater. First, the fluid flow equation is solved to obtain velocity and pressure profiles. Steady-state concentration profiles were obtained for various values of diffusion coefficient ( D ), baseline, and input concentrations. The results showed that decreasing the diffusion coefficient D increased the number of pollutants for convective transport and decreased the number of pollutants that diffused from the entrance. Although groundwater is not completely safe, it is concluded that experimental studies are necessary decision-making basis for water resource protection, especially in water pollution emergencies.
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Tracy, Fred Thomas, Thomas C. Oppe und Maureen K. Corcoran. „A comparison of MPI and co-array FORTRAN for large finite element variably saturated flow simulations“. Scalable Computing: Practice and Experience 19, Nr. 4 (29.12.2018): 423–32. http://dx.doi.org/10.12694/scpe.v19i4.1468.
Annotation:
The purpose of this research is to determine how well co-array FORTRAN (CAF) performs relative to Message Passing Interface (MPI) on unstructured mesh finite element groundwater modelling applications with large problem sizes and core counts. This research used almost 150 million nodes and 300 million 3-D prism elements. Results for both the Cray XE6 and Cray XC30 are given. A comparison of the ghost-node update algorithms with source code provided for both MPI and CAF is also presented.
46
Lyons, Richard T., Richard C. Peralta und Partha Majumder. „Comparing Single-Objective Optimization Protocols for Calibrating the Birds Nest Aquifer Model—A Problem Having Multiple Local Optima“. International Journal of Environmental Research and Public Health 17, Nr. 3 (30.01.2020): 853. http://dx.doi.org/10.3390/ijerph17030853.
Annotation:
To best represent reality, simulation models of environmental and health-related systems might be very nonlinear. Model calibration ideally identifies globally optimal sets of parameters to use for subsequent prediction. For a nonlinear system having multiple local optima, calibration can be tedious. For such a system, we contrast calibration results from PEST, a commonly used automated parameter estimation program versus several meta-heuristic global optimizers available as external packages for the Python computer language—the Gray Wolf Optimization (GWO) algorithm; the DYCORS optimizer framework with a Radial Basis Function surrogate simulator (DRB); and particle swarm optimization (PSO). We ran each optimizer 15 times, with nearly 10,000 MODFLOW simulations per run for the global optimizers, to calibrate a steady-state, groundwater flow simulation model of the complex Birds Nest aquifer, a three-layer system having 8 horizontal hydraulic conductivity zones and 25 head observation locations. In calibrating the eight hydraulic conductivity values, GWO averaged the best root mean squared error (RMSE) between observed and simulated heads—20 percent better (lower) than the next lowest optimizer, DRB. The best PEST run matched the best GWO RMSE, but both the average PEST RMSE and the range of PEST RMSE results were an order of magnitude larger than any of the global optimizers.
47
Abd-Elaty, Ismail, Martina Zeleňáková, Katarína Krajníková und Hany Abd-Elhamid. „Analytical Solution of Saltwater Intrusion in Costal Aquifers Considering Climate Changes and Different Boundary Conditions“. Water 13, Nr. 7 (04.04.2021): 995. http://dx.doi.org/10.3390/w13070995.
Annotation:
Groundwater contamination due to saltwater intrusion (SWI) has an extreme effect on freshwater quality. Analytical and numerical models could be used to investigate SWI. This study aims to develop an analytical solution to investigate SWI into coastal aquifers which was applied to a real case study at the Middle Nile Delta aquifer (MNDA). The study presented a new formula to predict the difference in depth of freshwater to seawater interface due to a change in boundary conditions. A Computer Program for Simulation of Three-Dimensional Variable-Density Ground-Water Flow and Transport (SEAWAT) is used for groundwater flow simulation and SWI and the results compared with the developed analytical solution. Four scenarios are considered in the study, including; the sea-level rise (SLR), reduction in recharge, over abstraction, and combination after 50 years (2070). The analytical solution gave good results compared to the numerical one where Equiline 1 intruded to 103 and 101.66 km respectively at the base case. The results also gave a good agreement between numerical and the analytical solution for SLR due to climate changes by 52.80 cm where the Equiline 1 reached to 105 and 103.45 km. However, the reduction in aquifer recharge by 18.50% resulted in an intrusion for the Equiline-1 to 111 and 108.25 km from the shoreline. Over pumping due to the increase in population by 89% has increased the SWI to reach 121,110.31 km, while it reached 131 and 111.32 km at a combination of the three scenarios, which represents the highest threatening scenario. Also, the difference between the two solutions reached 1.30%, 1.48%, 2.48%, 8.84%, and 15.02%, respectively for the base case and four scenarios. For the current case study, the analytical model gave good results compared to the numerical one, so that the analytical solution is recommended for similar studies, which could save the time and capabilities of computer required for the numerical solutions.
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Chen, Wenfang, Yaobin Zhang, Weiwei Shi, Yali Cui, Qiulan Zhang, Yakun Shi und Zexin Liang. „Analysis of Hydrogeochemical Characteristics and Origins of Chromium Contamination in Groundwater at a Site in Xinxiang City, Henan Province“. Applied Sciences 11, Nr. 24 (09.12.2021): 11683. http://dx.doi.org/10.3390/app112411683.
Annotation:
Hexavalent chromium contamination in groundwater has become a very serious and challenging problem. Identification of the groundwater chemical characteristics of the sites and their control mechanisms for remediation of pollutants is a significant challenge. In this study, a contaminated site in Xinxiang City, Henan Province, was investigated and 92 groundwater samples were collected from the site. Furthermore, the hydrogeochemical characteristics and the distribution patterns of components in the groundwater were analyzed by a combination of multivariate statistical analysis, Piper diagram, Gibbs diagram, ions ratio and hydrogeochemical simulation. The results showed that the HCO3-Cl-Mg-Ca type, SO4-HCO3-Na type, and HCO3-Mg-Ca-Na type characterize the hydrogeochemical composition of shallow groundwater and HCO3-Cl-Mg-Ca type, HCO3-Na-Mg type, and HCO3-SO4-Mg-Na-Ca type characterize the hydrogeochemical composition of deep groundwater. Ion ratios and saturation index indicated that the groundwater hydrogeochemical characteristics of the study area are mainly controlled by water–rock action and evaporative crystallization. The dissolution of halite, gypsum and anhydrite, the precipitation of aragonite, calcite and dolomite, and the precipitation of trivalent chromium minerals other than CrCl3 and the dissolution of hexavalent chromium minerals occurred in groundwater at the site. The minimum value of pH in groundwater at the site is 7.55 and the maximum value is 9.26. The influence of pH on the fugacity state of minerals was further investigated. It was concluded that the saturation index of dolomite, calcite, aragonite and MgCr2O4 increases with the increase of pH, indicating that these minerals are more prone to precipitation, and the saturation index of Na2Cr2O7, K2Cr2O7 and CrCl3 decreases with the increase of pH, implying that Na2Cr2O7, K2Cr2O7 and CrCl3 are more prone to dissolution. The saturation index of the remaining minerals is less affected by pH changes. The study can provide a scientific basis for groundwater remediation.
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Wang, Weishu, Chuang Li, Yun-Ze Li, Man Yuan und Tong Li. „Numerical Analysis of Heat Transfer Performance of In Situ Thermal Remediation of Large Polluted Soil Areas“. Energies 12, Nr. 24 (05.12.2019): 4622. http://dx.doi.org/10.3390/en12244622.
Annotation:
In recent years soil contamination has become a global problem because of industrial development. In situ thermal remediation has been proposed recently to not only lower costs, but also reduce the environmental impact compared to other soil remediation technologies such as chemical remediation. During the soil thermal remediation process, factors such as soil type and water content affecting the heat transfer pose challenges. In this study, a simple mathematical model is presented and the heat transfer performance during the soil heating process is researched via COMSOL Multiphysics 5.3 software (COMSOL Inc., Stockholm, Sweden). The temperature distribution and heating period under different operating conditions are evaluated. The simulation results show that the average soil temperature exhibits three stages during the heating process. First, soil is heated from the ambient temperature to the water boiling temperature (100 °C). Then, the soil stays at the water boiling temperature for a while before reaching the target temperature. Simultaneously, the effects of initial water content and groundwater flow on heat transfer are also studied. In addition, the results of a simulation can provide a reference for in situ heating remediation technology.
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Andrássy, Tomáš, und Dana Baroková. „Numerical modeling of groundwater flow close to drinking water resources during flood events“. Pollack Periodica 11, Nr. 1 (April 2016): 43–54. http://dx.doi.org/10.1556/606.2016.11.1.5.