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Du, Shouhong, Larry S. Fung, and Ali H. Dogru. "Aquifer Acceleration in Parallel Implicit Field-Scale Reservoir Simulation." SPE Journal 23, no. 02 (February 12, 2018): 614–24. http://dx.doi.org/10.2118/182686-pa.
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Summary Grid coarsening outside of the areas of interest is a common method to reduce computational cost in reservoir simulation. Aquifer regions are candidates for grid coarsening. In this situation, upscaling is applied to the fine grid to generate coarse-grid flow properties. The efficacy of the approach can be judged easily by comparing the simulation results between the coarse-grid model and the fine-grid model. For many reservoirs in the Middle East bordered by active aquifers, transient water influx is an important recovery mechanism that needs to be modeled correctly. Our experience has shown that the standard grid coarsening and upscaling method do not produce correct results in this situation. Therefore, the objective of this work is to build a method that retains the fine-scale heterogeneities to accurately represent the water movement, but to significantly reduce the computational cost of the aquifer grids in the model. The new method can be viewed as a modified two-level multigrid (MTL-MG) or a specialized adaptation of the multiscale method. It makes use of the vertical-equilibrium (VE) concept in the fine-scale pressure reconstruction in which it is applicable. The method differs from the standard grid coarsening and upscaling method in which the coarse-grid properties are computed a priori. Instead, the fine-scale information is restricted to the coarse grid during Newton's iteration to represent the fine-scale flow behavior. Within the aquifer regions, each column of fine cells is coarsened vertically based on fine-scale z-transmissibility. A coarsened column may consist of a single amalgamated aquifer cell or multiple vertically disconnected aquifer cells separated by flow barriers. The pore volume (PV), compressibility, and lateral flow terms of the coarse cell are restricted from the fine-grid cells. The lateral connectivity within the aquifer regions and the one between the aquifer and the reservoir are honored, inclusive of the fine-scale description of faults, pinchouts, and null cells. Reservoir regions are not coarsened. Two alternatives exist for the fine-scale pressure reconstruction from the coarse-grid solution. The first method uses the VE concept. When VE applies, pressure variation can be analytically computed in the solution update step. Otherwise, the second method is to apply a 1D z-line solve for the fine-scale aquifer pressure from the coarse-grid solution. Simulation results for several examples are included to demonstrate the efficacy and efficiency of the method. We have applied the method to several Saudi Arabian complex full-field simulation models in which the transient aquifer water influx has been identified as a key factor. These models include dual-porosity/dual-permeability (DPDP) models, as well as models with faults and pinchouts in corner-point-geometry grids, for both history match and prediction period. The method is flexible and allows for the optional selection of aquifer regions to be coarsened, either only peripheral aquifers or both the peripheral and bottom aquifers. The new method gives nearly identical results compared with the original runs without coarsening, but with significant reduction in computer time or hardware cost. These results will be detailed in the paper.
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Zhai, Wen, Wei Li, Yanli Huang, Shenyang Ouyang, Kun Ma, Junmeng Li, Huadong Gao, and Peng Zhang. "A Case Study of the Water Abundance Evaluation of Roof Aquifer Based on the Development Height of Water-Conducting Fracture Zone." Energies 13, no. 16 (August 7, 2020): 4095. http://dx.doi.org/10.3390/en13164095.
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In the eastern mining area of Ningxia, China, multi-layered sandstone aquifers are widely distributed in the underground. However, the water abundance of these aquifers is not clear, which brings great challenges to the prevention and control of mine water disaster. In this paper, five mining areas in eastern Ningxia were taken as the study area, and the distribution characteristics of aquifer and the mine water filling source were analyzed through the analysis of geological data and numerical simulation. Finally, the lithology influencing index (LII) was constructed, and the water abundance of the aquifer was evaluated. The results show that the sandstone aquifer III in the lower part of the Jurassic Zhiluo formation is the main water-source aquifer of the #2 coal seam in the study area, while the middle aquifer II and the upper aquifer I are indirect water-source aquifers; the areas with extremely strong and strong water abundance are Maiduoshan, Hongliu, the south of Shicaocun, southeast and southwest of Meihuajing, and the central and southern areas of Shuangma mining areas; when the depth of water drainage boreholes in the roof reaches the development height of the water-conducting fracture zone, the pre-drainage measures can effectively control the mining inrush water of the working face and ensure the safety production. This research is of great significance to the prevention and control of mine water disaster.
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Bai, Erhu, Wenbing Guo, Dongsheng Zhang, Yi Tan, Mingjie Guo, and Gaobo Zhao. "Using the Magnetotelluric Method for Detecting Aquifer Failure Characteristics under High-Intensity Mining of Thick Coal Seams." Energies 12, no. 22 (November 19, 2019): 4397. http://dx.doi.org/10.3390/en12224397.
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In the ecologically fragile mining area of northwest China, high-intensity mining has seriously affected the aquifer and surface eco-environment. In order to better implement water-preserved mining in ecologically fragile areas, the aquifer failure characteristics should be first detected accurately; therefore, it is necessary to find a convenient and fast detection method. Based on the analysis of the basic principles and influencing factors of the magnetotelluric (MT) method, the feasibility of using the MT method to detect aquifer failure is verified by testing the mined area with MT detection and field borehole measurement. Subsequently, the failure characteristics of overburden and unconsolidated aquifers under high-intensity mining are studied by MT detection and physical simulation. By comparing the physical simulation with the field measurement from the aspects of the maximum surface subsidence, interval of periodic weighting and step cracks, the reliability of the height of the water flowing fracture zone and caving zone obtained from physical simulation is verified. The analysis from MT detection and physical simulation shows that the results of the two methods are in accord with each other, which further confirms that the MT method can be used to detect the failure of overburdened structures and aquifers. The penetrating fractures are the main channel for the downward seepage of water resources, which is caused by the “two-zone” of overburden model and located in the “dimple” shape in the apparent resistivity (AR) isogram. It can provide a reference and technical support for the corresponding new water-preserved mining technology and the construction of digital mines.
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Liu, Ruxue, Xinru Yang, Jiayin Xie, Xiaoyu Li, and Yongsheng Zhao. "Experimental Investigation on the Effects of Ethanol-Enhanced Steam Injection Remediation in Nitrobenzene-Contaminated Heterogeneous Aquifers." Applied Sciences 11, no. 24 (December 17, 2021): 12029. http://dx.doi.org/10.3390/app112412029.
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Steam injection is an effective technique for the remediation of aquifers polluted with volatile organic compounds. However, the application of steam injection technology requires a judicious selection of stratum media because the remediation effect of hot steam in heterogeneous layers with low permeability is not suitable. In this study, the removal effect of nitrobenzene in an aquifer was investigated through a series of two-dimensional sandbox experiments with different stratigraphic structures. Four types of alcohols were used during steam injection remediation to enhance the removal effect of nitrobenzene (NB)-contaminated heterogeneous aquifers. The principle of the removal mechanism of alcohol-enhanced organic compounds is that alcohols can reduce the surface tension of the contaminated water, resulting in Marangoni convection, thereby enhancing mass and heat transfer. The addition of alcohol may also reduce the azeotropic temperature of the system and enhance the volatility of organic compounds. The study revealed that all four alcohol types could reduce the surface tension from 72 mN/m to <30 mN/m. However, among these, only ethanol reduced the azeotropic temperature of NB by 15 °C, thereby reducing energy consumption and remediation costs. Therefore, ethanol was selected as an enhancing agent to reduce both surface tension and azeotropic temperature during steam injection. In the 2-D simulation tank, the interface between the low-and high-permeability strata in the layered heterogeneous aquifer had a blocking effect on steam transportation, which in turn caused a poor remediation effect in the upper low-permeability stratum. In the lens heterogeneous aquifer, steam flows around the lens, thereby weakening the remediation effect. After adding ethanol to the low-permeability zone, Marangoni convection was enhanced, which further enhanced the mass and heat transfer. In the layered and lens heterogeneous aquifers, the area affected by steam increased by 13% and 14%, respectively. Moreover, the average concentration of NB was reduced by 51% in layered heterogeneous aquifers and by 58% in low-permeability lenses by ethanol addition. These findings enhance the remediation effect of steam injection in heterogeneous porous media and contribute to improve the remediation efficiency of heterogeneous aquifers by steam injection.
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Zi-Zhao, Cai, Zhang Fa-Wang, Xu Wei, and Chen Li. "Prediction on Water-flowing Fractured Region Based on 3D Simulation Technology." Open Civil Engineering Journal 10, no. 1 (June 30, 2016): 349–60. http://dx.doi.org/10.2174/1874149501610010349.
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Caving zone and fractured zone both appear in the Changzhi Basin in China as the a large number of coal are mined from the area. Based on ore cluster mining and on GIS (Geographic Information System) technology, in the paper, it combines the 3-D (three dimensional) simulation technology and adopts the spacial interpolation method to develop the 3-D stratigraphic model of the studied region, the 3D stratigraphic model and the division idea which is applicable for the study region are obtained. The virtual drilling technology is applied to obtain precise stratigraphic data and calculate the heights of the caving zone and fractured zone of Changzhi Basin, their relative locations to the overlying aquifer and the water-flowing fractured region of influence based on computer-simulated data are both analyzed. In addition, it also puts forward the concept of effective water-flowing fractured rate, which lays a solid foundation for further study on the heterogeneous evolution of the spatial structure of regional aquifers after the coal mining which also can provide a data support for future studies on the heterogeneous evolution features of water-bearing media.
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Urych, Tomasz, and Adam Smoliński. "Numerical Modeling of CO2 Migration in Saline Aquifers of Selected Areas in the Upper Silesian Coal Basin in Poland." Energies 12, no. 16 (August 12, 2019): 3093. http://dx.doi.org/10.3390/en12163093.
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Determining the characteristics of the dynamic behavior of carbon dioxide in a rock mass is a stage in the process of assessing a potential CO2 storage reservoir. The aim of this study was to analyze the process of CO2 storage in saline aquifers of the selected regions of the Upper Silesian Coal Basin in Poland. The construction of dynamic simulation models was based on static models of real deposit structures developed on a regional scale. Different simulation variants of the CO2 storage process were adopted, varying in terms of injection efficiency and duration of individual simulation phases. The analysis examined the influence of the degree of hydrodynamic openness of the structure on the CO2 storage process, in each of the variants. The results of numerical simulations showed that among the three analyzed geological formations, the Dębowiec formation is the most prospective for potential CO2 storage and is characterized by the most favorable geological and hydrogeological parameters. In the best variant of the simulation, in which the safety of CO2 storage in the rock mass was taken into account, the total amount of CO2 injected in a single directional well was approximately 8.54 million Mg of CO2 during 25 years of injection.
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Abd-Elaty, Ismail, Martina Zeleňáková, Katarína Krajníková, and Hany Abd-Elhamid. "Analytical Solution of Saltwater Intrusion in Costal Aquifers Considering Climate Changes and Different Boundary Conditions." Water 13, no. 7 (April 4, 2021): 995. http://dx.doi.org/10.3390/w13070995.
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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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Li, Yuan-Heng, Chien-Hao Shen, Cheng-Yueh Wu, and Bieng-Zih Hsieh. "Numerical Study of CO2 Geological Storage in Saline Aquifers without the Risk of Leakage." Energies 13, no. 20 (October 10, 2020): 5259. http://dx.doi.org/10.3390/en13205259.
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The purpose of this study is to reduce the risk of leakage of CO2 geological storage by injecting the dissolved CO2 solution instead of the supercritical CO2 injection. The reservoir simulation method is used in this study to evaluate the contributions of the different trapping mechanisms, and the safety index method is used to evaluate the risk of CO2 leakage. The function of the dissolved CO2 solution injection is performed by a case study of a deep saline aquifer. Two scenarios are designed in this study: the traditional supercritical CO2 injection and the dissolved CO2 solution injection. The contributions of different trapping mechanisms, plume migrations, and the risk of leakage are evaluated and compared. The simulation results show that the risk of leakage via a natural pathway can be decreased by the approach of injecting dissolved CO2 solution instead of supercritical CO2. The amount of the CO2 retained by the safe trapping mechanisms in the dissolved CO2 solution injection scenario is greater than that in the supercritical CO2 scenario. The process of CO2 mineralization in the dissolved CO2 solution injection scenario is also much faster than that in the supercritical CO2 scenario. Changing the injection fluid from supercritical CO2 to a dissolved CO2 solution can significantly increase the safety of the CO2 geological storage. The risk of CO2 leakage from a reservoir can be eliminated because the injected CO2 can be trapped totally by safe trapping mechanisms.
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Booij, M., A. Leijnse, S. Haldorsen, M. Heim, and H. Rueslåtten. "Subpermafrost Groundwater Modelling in Ny-Ålesund, Svalbard." Hydrology Research 29, no. 4-5 (August 1, 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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Mokhtari, Bahram, and Alireza Bahramian. "Flow monitoring of underground aquifers by interfacial tensiometry." Flow Measurement and Instrumentation 67 (June 2019): 1–9. http://dx.doi.org/10.1016/j.flowmeasinst.2019.03.007.
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Behl, Elizabeth. "Computer Models for Fate Assessment During the Registration Process: Data Needs." Weed Technology 6, no. 3 (September 1992): 696–700. http://dx.doi.org/10.1017/s0890037x00036071.
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Computer models designed to simulate the fate and transport of pesticide residues in surface runoff and water that recharges shallow aquifers are used at several stages in the regulation of pesticides. Models can be a powerful tool to identify environments in which pesticides are more mobile and are more likely to impact ground-water quality. Models can also be used to highlight pesticides that can contaminate surface or ground water at an early stage of the registration process. At present, models are utilized primarily as comparative tools to identify which compounds should be examined on a priority basis. Results may be used to calibrate numerical models and estimate the long term impact on the environment from the use of a particular product or its alternatives. To date, field monitoring studies have been required for over 40 chemicals by the Office of Pesticide Programs (OPP) to evaluate the leaching potential of pesticides under realistic usage conditions. As the capabilities of models improve and linkages are developed between databases and the models, computer simulation models will play an increasingly important role in the Environmental Protection Agency's (EPA's) efforts to manage pesticide use to prevent adverse effects on the environment.
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Collados-Lara, Antonio-Juan, David Pulido-Velazquez, and Eulogio Pardo-Igúzquiza. "A Statistical Tool to Generate Potential Future Climate Scenarios for Hydrology Applications." Scientific Programming 2020 (June 29, 2020): 1–11. http://dx.doi.org/10.1155/2020/8847571.
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Global warming associated with greenhouse emissions will modify the availability of water resources in the future. Methodologies and tools to assess the impacts of climate change are useful for policy making. In this work, a new tool to generate potential future climate scenarios in a water resources system from historical and regional climate models’ information has been developed. The GROUNDS tool allows generation of the future series of precipitation, temperature (minimum, mean, and maximum), and potential evapotranspiration. It is a valuable tool for assessing the impacts of climate change in hydrological applications since these variables play a significant role in the water cycle, and it can be applicable to any case study. The tool uses different approaches and statistical correction techniques to generate individual local projections and ensembles of them. The non-equifeasible ensembles are created by combining the individual projections whose control or corrected control simulation has a better fit to the historical series in terms of basic and droughts statistics. In this work, the tool is presented, and the methodology implemented is described. It is also applied to a case study to illustrate how the tool works. The tool was previously tested in different typologies of water resources systems that cover different spatial scales (river basin, aquifer, mountain range, and country), obtaining satisfactory results. The local future scenarios can be propagated through appropriate hydrological models to study the impacts on other variables (e.g., aquifer recharge, chloride concentration in coastal aquifers, streamflow, snow cover area, and snow depth). The tool is also useful in quantifying the uncertainties of the future scenarios by combining them with stochastic weather generators.
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Strzelecki, Michał. "Numerical Three-Dimensional Model of Airport Terminal Drainage System." Studia Geotechnica et Mechanica 36, no. 1 (March 1, 2014): 111–19. http://dx.doi.org/10.2478/sgem-2014-0013.
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Abstract During the construction of an airport terminal it was found that as a result of the hydrostatic pressure of underground water the foundation plate of the building had dangerously shifted in the direction opposite to that of the gravitational forces. The only effective measure was to introduce a drainage system on the site. The complex geology of the area indicated that two independent drainage systems, i.e., a horizontal system in the Quaternary beds and a vertical system in the Tertiary water-bearing levels, were necessary. This paper presents numerical FEM calculations of the two drainage systems being part of the airport terminal drainaged esign. The computer simulation which was carried out took into consideration the actual effect of the drainage systems and their impact on the depression cone being formed in the two aquifers.
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Aliagas, Carles, Agustí Pérez-Foguet, Roc Meseguer, Pere Millán, and Carlos Molina. "A Low-Cost and Do-It-Yourself Device for Pumping Monitoring in Deep Aquifers." Electronics 11, no. 22 (November 18, 2022): 3788. http://dx.doi.org/10.3390/electronics11223788.
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Water crises due to climate change, high population growth and increasing demands from industry and agriculture claim for increasing efficiency and universalizing water resources management strategies and techniques. Water monitoring helps providing necessary evidences for making sound decisions about managing water resources both now and in the future. In this work, a low cost and “do it yourself” communication device is proposed to record water production and energy consumption of electric pumpings from deep boreholes/wells, and to predict the impact of the ongoing and previous pumpings in the evolution of the water level in the aquifer. The proposal incorporates an edge-computing approach for the simulation of the aquifer response in real-time. Computation of results of interest is performed at the sensor, minimizing communication requirements and ensuring almost immediate results. An approximated solution to physically based modeling of aquifer response is computed thanks to the a priori expression of the water level time evolution in a reduced basis. The accuracy is enough to detect deviations from expected behaviour. The energy consumption of the device is very much reduced with respect to that of a full modelling, which can be computed off-line for calibrating reduced model parameters and perform detailed analyses. The device is tested in a real scenario, in a mountain subbasin of the Ebro river in Spain, obtaining a good trade-off between performance, price, and energy consumption.
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Chapuis, Robert P., and Louis Sabourin. "Effects of installation of piezometers and wells on groundwater characteristics and measurements." Canadian Geotechnical Journal 26, no. 4 (November 1, 1989): 604–13. http://dx.doi.org/10.1139/t89-073.
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The results of a variable-head permeability test can be used to check whether a piezometer or sampling well has been successfully sealed in the soil and to detect hydraulic short circuits and possible cross-contamination between aquifers. An improper seal is a well-known cause of hydraulic short circuit. In some instances, also, although the tubing has been sealed over its full length, the water level in the pipe is not representative of the actual piezometric head. An example shows that the values of hydraulic conductivity determined using several test methods varied in a 1:6 ratio before detection of a piezometric error. The resulting correction reduced the variation in k to ± 12%. The causes of hydraulic short circuits have been investigated using computer simulations. It has been concluded that large errors recorded in the field are due to internal erosion of natural soils around the casing during drilling operations or development. The hydraulic damage to soils is documented. An analytical solution has been written for a simple case of hydraulic short circuit. Its theoretical predictions confirm the validity of the computer simulation. In light of experience, recommendations are proposed to reduce hydraulic damage, therefore improving the reliability of piezometric measurements and representativeness of groundwater samples. Key words: permeability, field test, piezometer, sealing, drilling, water level.
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Zhao, Chunbo, and Wencheng Song. "Mechanical Models for Comparative Analysis of Failure Characteristics and Groundwater Inrush of Coal Seam Floors." Applied Sciences 12, no. 23 (November 28, 2022): 12164. http://dx.doi.org/10.3390/app122312164.
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Mining activities conducted above aquifers run the risk of groundwater outburst through fractured floor strata. However, the failure mechanism of the seam floor and the variability in its stability with varying dips remain unclear. Considering the influence of excavation-induced pressure, hydraulic pressure and strata dip, two kinds of analytical models were proposed in this study, which mainly included the hydraulic mechanical model and the key stratum model. These models were applied to comparatively investigate the failure characteristics and inrush risk of horizontal and inclined floors, and then confirmed by numerical simulation. The theoretical calculations reveal that the vertical failure ranges of horizontal and inclined floor strata exhibit approximate “inverted saddle” shapes along the inclination, and have the characteristics of symmetrical distribution and “lower-large/upper-small”, respectively, which is generally consistent with the simulated and measured observations. The theoretical maximum depths of damage within horizontal and inclined floor strata are roughly 12 m and 15 m, slightly lower than the result of numerical simulation. Compared with the remaining horizontal layer, the zone close to the lower boundary of the inclined key strata beneath the goaf incurs the most damage, which corresponds well to the distribution of vertical disturbance ranges. Therefore, the theoretical risk of groundwater outburst from the inclined floor after coal extraction is relatively higher than that from the horizontal floor. The mechanical models established in this study could elucidate the mechanism inducing floor failure and water inrush above a confined aquifer, and thus provide valuable insights for the risk assessment of water-related disasters in underground engineering.
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Maller, Márton, András Rehák, and Géza Hajnal. "Water level fluctuation in karst aquifers in the Transdanubian range (Hungary)." Pollack Periodica 13, no. 3 (December 2018): 151–62. http://dx.doi.org/10.1556/606.2018.13.3.15.
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Luboń, Katarzyna. "Influence of Injection Well Location on CO2 Geological Storage Efficiency." Energies 14, no. 24 (December 20, 2021): 8604. http://dx.doi.org/10.3390/en14248604.
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An analysis of the influence of injection well location on CO2 storage efficiency was carried out for three well-known geological structures (traps) in deep aquifers of the Lower Jurassic Polish Lowlands. Geological models of the structures were used to simulate CO2 injection at fifty different injection well locations. A computer simulation showed that the dynamic CO2 storage capacity varies depending on the injection well location. It was found that the CO2 storage efficiency for structures with good reservoir properties increases with increasing distance of the injection well from the top of the structure and with increasing depth difference to the top of the structure. The opposite is true for a structure with poor reservoir properties. As the quality of the petrophysical reservoir parameters (porosity and permeability) improves, the location of the injection well becomes more important when assessing the CO2 storage efficiency. Maps of dynamic CO2 storage capacity and CO2 storage efficiency are interesting tools to determine the best location of a carbon dioxide injection well in terms of gas storage capacity.
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Vergnes, Jean-Pierre, Nicolas Roux, Florence Habets, Philippe Ackerer, Nadia Amraoui, François Besson, Yvan Caballero, et al. "The AquiFR hydrometeorological modelling platform as a tool for improving groundwater resource monitoring over France: evaluation over a 60-year period." Hydrology and Earth System Sciences 24, no. 2 (February 13, 2020): 633–54. http://dx.doi.org/10.5194/hess-24-633-2020.
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Abstract. The new AquiFR hydrometeorological modelling platform was developed to provide short-to-long-term forecasts for groundwater resource management in France. This study aims to describe and assess this new tool over a long period of 60 years. This platform gathers in a single numerical tool several hydrogeological models covering much of the French metropolitan area. A total of 11 aquifer systems are simulated through spatially distributed models using either the MARTHE (Modélisation d'Aquifères avec un maillage Rectangulaire, Transport et HydrodynamiquE; Modelling Aquifers with Rectangular cells, Transport and Hydrodynamics) groundwater modelling software programme or the EauDyssée hydrogeological platform. A total of 23 karstic systems are simulated by a lumped reservoir approach using the EROS (Ensemble de Rivières Organisés en Sous-bassins; set of rivers organized in sub-basins) software programme. AquiFR computes the groundwater level, the groundwater–surface-water exchanges and the river flows. A simulation covering a 60-year period from 1958 to 2018 is achieved in order to evaluate the performance of this platform. The 8 km resolution SAFRAN (Système d'Analyse Fournissant des Renseignements Adaptés à la Nivologie) meteorological analysis provides the atmospheric variables needed by the SURFEX (SURFace EXternalisée) land surface model in order to compute surface runoff and groundwater recharge used by the hydrogeological models. The assessment is based on more than 600 piezometers and more than 300 gauging stations corresponding to simulated rivers and outlets of karstic systems. For the simulated piezometric heads, 42 % and 60 % of the absolute biases are lower than 2 and 4 m respectively. The standardized piezometric level index (SPLI) was computed to assess the ability of AquiFR to identify extreme events such as groundwater floods or droughts in the long-term simulation over a set of piezometers used for groundwater resource management. A total of 56 % of the Nash–Sutcliffe efficiency (NSE; Ef) coefficient calculations between the observed and simulated SPLI time series are greater than 0.5. The quality of the results makes it possible to consider using the platform for real-time monitoring and seasonal forecasts of groundwater resources as well as for climate change impact assessments.
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Cinar, Alp, Xiang Sun, Kenichi Soga, Xiaoyu Lu, Peter Nico, and Patrick Dobson. "A simplified method to evaluate geothermal storage in an aquifer with consideration of heat transfer between aquifer and caprock/baserock." E3S Web of Conferences 205 (2020): 07007. http://dx.doi.org/10.1051/e3sconf/202020507007.
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Storing and extracting heat during different seasons of the year is possible through the utilization of a ground aquifer with an open loop Ground Source Heat Pump (GSHP) system. Being able to predict the hydrothermal performance of geothermal storage is required for an efficient operation of the system for cooling and heating of buildings. Complex 2D and 3D hydrothermal numerical models can simulate the thermal performance of geothermal storage accurately but often lack the desired computational speed for conducting large number of simulations for performance optimization. Instead, a 1D radial model can be used to conduct fast evaluation. However, it is important that the model computes the amount of heat loss from an aquifer into the overburden and underlying layers accurately to evaluate the amount of geothermal storage in the aquifer at different times. In this study, a source term is introduced into a 1D model to simulate the heat transfer between the aquifer and caprock/baserock in the vertical direction. The following two heat loss models are introduced in the heat advection-conduction equation: (i) Newton’s heating/cooling law, which leads to a closed form solution, and (ii) a conduction-based semi-analytical model, which requires a 1D finite element solution. When compared to a full 2D axisymmetric simulation result, it was found that the Newton’s heating/cooling law model with a constant heat transfer coefficient works well in cases of fast heat flow rate in thick aquifers of around 100 meters. But large errors in estimating heat dissipation are observed in cases with low heat flow rate in thin aquifers, especially for simulations exceeding two to five years. On the other hand, the model with the conduction-based semi-analytical solution gives a better match for these conditions.
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Rudolph, D. L., and 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, no. 5 (October 1, 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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Nmegbu, C. G. J., Orisa F. Ebube, and Emmanuel Aniedi Edet. "Comparative Study of Oil Recovery Factor Determination for Edge and Bottom Water Drive Mechanism Using Water Influx Models." European Journal of Engineering and Technology Research 6, no. 5 (July 2, 2021): 1–9. http://dx.doi.org/10.24018/ejers.2021.6.5.2493.
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The purpose of this research work is to comparatively study the oil recovery factor from two major aquifer geometry (Bottom and Edge water aquifer) using water aquifer model owing to the fact that most if not every reservoir is bounded by a water aquifer with relative size content (Most Large). These aquifers are pivotal in oil recovery factor (percent%), Cumulative oil produced (MMSTB) as well as overall reservoir performance the methodology utilized in this study involves; Identification of appropriate influx models were utilized for aquifer characterization. The characterizes of the Niger Delta reservoir aquifer considered include aquifer permeability, aquifer porosity etc. Estimation of aquifer properties is achieved by using regressed method in Material Balance Software (MBAL). This approach involves History Matching of average reservoir pressure with computed pressure of the reservoir utilizing production data and PVT data. The computed pressure from model is history matched by regressing most uncertain parameters in aquifer such as aquifer size, permeability, and porosity. Historic production data was imputed into the MBAL Tank Model, the production data was matched with the model simulation by regressing on rock and fluid parameters with high uncertainty. The match parameters were recorded as the base parameter and other sensitivity on aquifer parameters using the Fetkovich model for the bottom and edge water drive. The average percentage increase in oil cumulative volume was 0.40% in fovour of bottom water drive. Further sensitivity on cumulative oil recovered showed the increase in reservoir size with increasing aquifer volumes increases oil production exponentially in bottom water drive whereas edge water drive increased linearly. Aquifer volume, aquifer permeability showed linear relationship with bottom and edge water drive.
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Nmegbu, C. G. J., Orisa F. Ebube, and Emmanuel Aniedi Edet. "Comparative Study of Oil Recovery Factor Determination for Edge and Bottom Water Drive Mechanism Using Water Influx Models." European Journal of Engineering and Technology Research 6, no. 5 (July 2, 2021): 1–9. http://dx.doi.org/10.24018/ejeng.2021.6.5.2493.
Full textAbstract:
The purpose of this research work is to comparatively study the oil recovery factor from two major aquifer geometry (Bottom and Edge water aquifer) using water aquifer model owing to the fact that most if not every reservoir is bounded by a water aquifer with relative size content (Most Large). These aquifers are pivotal in oil recovery factor (percent%), Cumulative oil produced (MMSTB) as well as overall reservoir performance the methodology utilized in this study involves; Identification of appropriate influx models were utilized for aquifer characterization. The characterizes of the Niger Delta reservoir aquifer considered include aquifer permeability, aquifer porosity etc. Estimation of aquifer properties is achieved by using regressed method in Material Balance Software (MBAL). This approach involves History Matching of average reservoir pressure with computed pressure of the reservoir utilizing production data and PVT data. The computed pressure from model is history matched by regressing most uncertain parameters in aquifer such as aquifer size, permeability, and porosity. Historic production data was imputed into the MBAL Tank Model, the production data was matched with the model simulation by regressing on rock and fluid parameters with high uncertainty. The match parameters were recorded as the base parameter and other sensitivity on aquifer parameters using the Fetkovich model for the bottom and edge water drive. The average percentage increase in oil cumulative volume was 0.40% in fovour of bottom water drive. Further sensitivity on cumulative oil recovered showed the increase in reservoir size with increasing aquifer volumes increases oil production exponentially in bottom water drive whereas edge water drive increased linearly. Aquifer volume, aquifer permeability showed linear relationship with bottom and edge water drive.
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Oh, Jewon, Daisuke Sumiyoshi, Masatoshi Nishioka, and Hyunbae Kim. "Examination of Efficient Operation Method of ATES System by Comparison Operation with WTES System of Existent Heat Storage System." Applied Sciences 11, no. 21 (November 3, 2021): 10321. http://dx.doi.org/10.3390/app112110321.
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Aquifer thermal energy storage (ATES) system is widely used mainly in Europe and USA. In this paper, we examined the efficient operation method of ATES by comparing it with the water thermal energy storage (WTES) system of an existent thermal energy storage (TES) system using simulation. This study uses three aquifers: pumping wells, thermal storage wells, and reducing wells. The initial temperature is 19.1 °C groundwater from the surrounding area. ATES systems use the same operating methods as WTES systems to reduce heat storage efficiency and increase energy consumption. The operation that combines the ATES system with the pre-cooling/pre-heating coil can be used for air conditioning operation even if the heat storage diffuses or the pumping temperature changes. The aquifer heat storage system was used for the pre-cooling/pre-heating coil, and the cooling power consumption was reduced by 20%. The heating operation could not maintain heat for a long time due to the influence of groundwater flowing in from the surroundings. Therefore, it is recommended to use the stored heat as soon as possible. When energy saving is important by introducing a pre-cooling/pre-heating coil, the operation is performed by storing heat at a low temperature close to geothermal heat and also using groundwater heat. In addition, if the reduction of peak power in the daytime is important, it is appropriate to operate so that the heat stored in the pre-cooling/pre-heating coil is used up as much as possible. As a result, it was found that it is effective to operate the ATES system in combination with a pre-cooling/pre-heating coil. In cooling operation, ATES-C1-7 was the lowest at coefficient of performance (COP) 2.4 and ATES-C2-14 was the highest at COP 3.7. In heating operation, ATES-H1-45 was the lowest at COP1.2, and in other cases, it was about the same at COP2.4-2.8. In terms of energy efficiency, the heating operation ATES-H1-45 had a low energy efficiency of 4.1 for energy efficiency ratio (EER) and 3.9 for seasonal energy efficiency ratio (SEER). In other cases, the energy efficiency was 8.2–12.4 for EER and 8.7–15.3 for SEER.
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Zhuk, Veronika, Oleksandr Piatkov, and Sergiy Tarambula. "Stress-strain state of the building foundations with taking into account the possible water saturation of loess soils." Bases and Foundations, no. 41 (December 17, 2020): 22–31. http://dx.doi.org/10.32347/0475-1132.41.2020.22-31.
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In Ukraine, the problem of construction on loess soils is relevant due to the widespread use of these soils and their negative property - the ability to give additional deformations of subsidence during water saturation. Flooding of territories by groundwater, emergency leaks from aquifers cause significant problems during the exploitation of buildings and engineering structures on such soils.
Computer simulation of the interaction of the building with the soil base allows to investigate the influence of all negative factors on the change of the stress-strain state of both the soil base and the load-bearing structures of the building.
The study of the interaction of the building with the foundation was performed using the software package LIRA-CAD. The interaction of the building with the soil base, the soils of which are able to reduce their mechanical properties with increasing humidity and give additional subsidence deformations, was studied. A variant design of the foundations was performed taking into account the occurrence of uneven deformations during subsidence of the loess soil due to its moistening in case of possible emergency losses from aquifers. The change of stress-strain state of the foundations of the building depending on the spatial rigidity of the foundation, the location of the soaking zone within the building spot, the shape and size of the zone of soil moisture is analyzed.
It is shown that taking into account the possible water saturation of loess soils when calculating the collaborate of the building with the soil base, allows to obtain stress-strain state of foundations and load-bearing structures of the aboveground part of the building for the most unfavorable conditions that may occur. The search for the optimal variant of the foundation structures of the building, which, while remaining cost-effective, provides reliable operation of the building in conditions of possible occurrence of uneven deformations of subsidence of the soil base during water saturation of the layer of loess soils.
According to the research results, a rational variant of the foundation structures has been designed taking into account the possible occurrence of non-uniform deformations.
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Wildenborg, A. F. B., B. Orlic, J. F. Thimus, G. de Lange, S. de Cock, C. S. de Leeuw, and E. J. M. Veling. "Radionuclide transport in clay during climate change." Netherlands Journal of Geosciences - Geologie en Mijnbouw 82, no. 1 (April 2003): 19–30. http://dx.doi.org/10.1017/s0016774600022769.
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AbstractThe Dutch national research programme into the feasibility of retrievable storage of radioactive waste (CORA Programme Phase I; CORA: Comité Opslag Radioactief Afval = Committee on Radioactive Waste Disposal) examined the suitability of Tertiary clay deposits for such storage. Long-term isolation – up to 1 million years – of high-level radioactive waste under varying conditions is essential. A key concern is the hydro-mechanical response of the clay deposits in which radioactive waste might possibly be stored, in particular during glacial climate conditions as has happened repeatedly in the Netherlands during the Pleistocene. To evaluate this possibility hydro-mechanical computer simulations and mechanical laboratory experiments have been performed to analyse the effects of glacial loading by a thousand-metre-thick ice sheet on the permeability characteristics, fluid flow rates and the associated migration of radio-nuclides both within and out of Tertiary clays.Glacial loading causes the expulsion of pore water from deeply buried clay deposits into adjoining aquifers. The rates and duration of the consolidation-driven outflow of water from the clay deposit, are very sensitive to the permeability of the clay and the dynamics of the advancing ice sheet. The maximum outflow rate of pore water is 1 mm per year. This rate is approximately three times faster than the flow rate of water in clay prior to ice loading. These preliminary simulation studies also indicate that cyclic loading can result in more rapid migration of radio-nuclides in clays. In clay deposits that are covered by a thick ice sheet, the contribution of dispersed transport relative to the total transport by diffusion amounts to 14%, assuming that there is no absorption of radio-nuclides by the clays and a longitudinal dispersivity of 50 m.
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Pagnozzi, Mauro, Gianluca Coletta, Guido Leone, Vittorio Catani, Libera Esposito, and Francesco Fiorillo. "A Steady-State Model to Simulate Groundwater Flow in Unconfined Aquifer." Applied Sciences 10, no. 8 (April 14, 2020): 2708. http://dx.doi.org/10.3390/app10082708.
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The hydraulic and hydrogeological features of the Caposele aquifer have been investigated by using a numerical groundwater flow model. In particular, groundwater flow simulations were performed for a multilayered, unconfined aquifer in steady-state conditions for different thicknesses of the aquifer’s saturated zone. The Caposele groundwater model was carried out starting from a generic model drained by a unique spring outlet in accordance with the geo-hydrological features of the study area. The conceptual model was built considering hydrogeological features of spring catchment, and was then implemented with the MODFLOW numerical code. A combined 2D-3D approach was adopted, and the model was calibrated on borehole data available for the time period 2012–2019. Different thicknesses of the aquifer were set, and a reliable relationship was found between the hydraulic head, saturated zone and hydraulic conductivity of the aquifer. Using the MODPATH package, the mean travel time (Darcian) of groundwater was computed for five different scenarios, corresponding to the model’s depths; the analysis that was performed shows that the travel time is higher for a greater and lower for a smaller thickness of the aquifer’s saturated zone, respectively. The Caposele aquifer model was zoned in different sectors, named flow pipe areas, that play different roles in groundwater recharge-discharge processes. A vector analysis was also carried out in order to highlight the ascendant flow near the spring zone.
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Timaniya, Aman, and 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, no. 5 (May 31, 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
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Fanchi, J. R. "Analytical Representation of the van Everdingen-Hurst Aquifer Influence Functions for Reservoir Simulation." Society of Petroleum Engineers Journal 25, no. 03 (June 1, 1985): 405–6. http://dx.doi.org/10.2118/12565-pa.
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Abstract Linear regression analysis has been used to develop some simple analytical expressions for the van Everdingen-Hurst aquifer influx influence functions. Regression results are presented for a variety of aquifer radius/reservoir radius ratios. The regression equations are designed for use in reservoir engineering applications, especially reservoir simulation. Introduction A reservoir-aquifer system can be modeled by using a reservoir simulator in which small gridblocks define the reservoir and increasingly larger gridblocks define the aquifer. This approach has the disadvantage of increased computer storage and computing time requirements because additional gridblocks are needed to model the aquifer. A widely used and more cost-effective means of representing an aquifer is to compute aquifer influx with an analytical model. Among the more popular analytical aquifer models in use today is the Carter-Tracy modification of the van Everdingen-Hurst unsteadystate aquifer influx calculation. The Carter-Tracy aquifer influx rate calculation requires information about dimensionless pressure p and its first derivative P as functions of dimensionless time t . Usually, the relationship between t and p is available in the reservoir simulator in tabular form for the infinite acting constant terminal rate case only. The program determines p and p for a given t by using a numerical program determines p and p for a given t by using a numerical interpolation scheme. An alternative approach that requires less computer work while providing equivalent or greater accuracy than the table look-up method is presented here. Description of Method A linear regression analysis has been used to develop analytical representations of the Carter-Tracy influence functions. The regression equations, the regression coefficients, correlation range limits, and measures of the linear regression validity are presented in Table 1 for a number of commonly encountered r/r cases. Plots of these expressions are shown in Figs. 1a and 1b. JPT P. 405
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Li, Wenliang, Qing Sun, Weiping Wang, Shisong Qu, Zhengxian Zhang, and Qiaoyi Xu. "Effective water quantity of multi-source water recharging aquifers in Yufuhe River based on groundwater and surface water semi-coupled modelling." Water Supply 19, no. 8 (August 1, 2019): 2280–87. http://dx.doi.org/10.2166/ws.2019.109.
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Abstract With rapid urbanisation, a karst water recharge area of the Jinan spring catchment was damaged. Thus, managed aquifer recharge projects were built in the western Jinan spring catchment to protect the water supply of the spring. Yufuhe River was selected as the study area to compute the effective recharge rate into karst aquifers. This strong seepage zone has a large gradient and undergoes a specific hydrogeological condition in which two strata of a gravel layer and limestone change to three strata of gravel, impermeable clay shale and limestone at the open window of the karst aquifers. A hydraulic model called HEC-RAS was applied to simulate the river stage, and a numerical groundwater model called HYDRUS-3D was adopted to simulate the groundwater mound dynamics and estimate river flow seepage into the aquifers. The effective recharge rates are 64.9%, 65.2% and 68.1% when the buried depths of groundwater are 40, 30 and 25 m. An analysis of the electric conductivity, water table, temperature and water volume data found an effective recharge rate of 68.3%. Results of field monitoring confirmed the accuracy of the numerical simulation and showed that most of the recharged water in the study reach can be effectively recharged into the karst aquifers.
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Saeb Salih, Ibrahim, and Hussain Ali Baker. "Development of a Semi-Analytical Type Curve of Transient Pressure Response in Complex Well-Reservoir Architectures." Iraqi Journal of Chemical and Petroleum Engineering 20, no. 2 (June 30, 2019): 61–69. http://dx.doi.org/10.31699/ijcpe.2019.2.8.
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The objective of the conventional well testing technique is to evaluate well- reservoir interaction through determining the flow capacity and well potential on a short-term basis by relying on the transient pressure response methodology. The well testing analysis is a major input to the reservoir simulation model to validate the near wellbore characteristics and update the variables that are normally function of time such as skin, permeability and productivity multipliers.
Well test analysis models are normally built on analytical approaches with fundamental physical of homogenous media with line source solution. Many developments in the last decade were made to increase the resolution of transient response derivation to meet the complexity of well and flow media.
Semi-analytical modeling for the pressure transient response in complex well architecture and complex reservoirs were adopted in this research. The semi analytical solution was based on coupling the boundary condition of source function to the well segment. Coupling well-reservoir on sliced based technique was used to re-produce homogenous isotropic media from several source functions of different properties. The approach can model different well geometries penetrated complex reservoirs. A computer package was prepared to model the pressure transient response of horizontal, dual-lateral, multi-lateral wells in complex anisotropic reservoirs, multilayered, compartmentalized, system of various boundary conditions such as: bottom support aquifers, edge supported, gas caps, interference of injection. The validity of the proposed model was successfully checked by using the commercial simulator.
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Qu, Zhi Hui, Yong Sheng Zhao, Bing Wang, and Li Na Jiao. "Study on Transformation Rules of Diesel Fuels Contaminated Aquifer." Advanced Materials Research 181-182 (January 2011): 636–41. http://dx.doi.org/10.4028/www.scientific.net/amr.181-182.636.
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Study on migration and transformation rules of diesel fuels pollution by using two-dimensional plexiglass tank to simulate underground aquifers. Through regular monitoring of the sampling ports in total petroleum hydrocarbon content of the water to determine the diesel fuels in the medium sand aquifer in the migration process, and compute out parameters of diesel fuels pollution in the medium sand aquifer in the mathematical model of migration. This prediction of diesel fuels pollution in the migration of sand media. The results showed: the highest values of different sampling ports used by the time its location is closely related to distance to sources, the concentration rose to the highest value used in a short time. The sampling ports far away from the pollution spilling place rose to the highest value of concentration used in a long time. After diesel fuels leaked 40 d later, the simulation of pollutants reached the bottom slot, and diesel fuels can be calculated transfered with a speed of 1cm•d-1, and then after 20 d more, TPH can be moved to simulate the water tank side pollution of the aquifer region.
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Ye, S., Y. Luo, J. Wu, P. Teatini, H. Wang, and X. Jiao. "Three dimensional numerical modeling of land subsidence in Shanghai." Proceedings of the International Association of Hydrological Sciences 372 (November 12, 2015): 443–48. http://dx.doi.org/10.5194/piahs-372-443-2015.
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Abstract. Shanghai city has been suffering land subsidence caused by overly exploitation of ground water since 1921, which is a serious problem for this coastal city with altitude of 2.2–4.8 m above mean sea level. The largest cumulative land subsidence amounted to 2.6 m in the downtown area. Measures to decrease the ground water exploitation, change the pumping aquifers, and increase aquifer artificial recharge have been used to mitigate land subsidence since 1961. It is necessary to develop a proper numerical model to simulate and predict land subsidence. In this study, a decoupled three-dimensional (3-D) finite element land subsidence model including a 3-D ground water flow model and a 3-D geo-mechanical model was developed to simulate the 3-D deformation of the aquifer systems in the center area of Shanghai. The area of downtown Shanghai is 660 km2, with 10 million inhabitants, dense high buildings, and 11 metro lines. The simulation spans the period from 1979 to 1995. Two different assumptions have been tested on the side boundary, i.e., precluding the three components of the displacement, or assuming a free-displacement condition. The distribution of calculated land subsidence and horizontal displacements in different aquifers was analyzed. The computed vertical displacement fitted well with the available observations. It has been verified that the two different assumptions on the lateral boundaries in the geo-mechanical model caused different results just limited on nodes close to boundary. The developed 3-D land subsidence model is reasonable and can be used to simulate and predict 3-D movement of aquifer systems in the center area of Shanghai, which could provide scientific support to local government in controlling land subsidence and differential movements of the land surface.
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Szymkiewicz, Adam, Julien Savard, and Beata Jaworska-Szulc. "Numerical Analysis of Recharge Rates and Contaminant Travel Time in Layered Unsaturated Soils." Water 11, no. 3 (March 16, 2019): 545. http://dx.doi.org/10.3390/w11030545.
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This study focused on the estimation of groundwater recharge rates and travel time of conservative contaminants between ground surface and aquifer. Numerical simulations of transient water flow and solute transport were performed using the SWAP computer program for 10 layered soil profiles, composed of materials ranging from gravel to clay. In particular, sensitivity of the results to the thickness and position of weakly permeable soil layers was carried out. Daily weather data set from Gdańsk (northern Poland) was used as the boundary condition. Two types of cover were considered, bare soil and grass, simulated with dynamic growth model. The results obtained with unsteady flow and transport model were compared with simpler methods for travel time estimation, based on the assumptions of steady flow and purely advective transport. The simplified methods were in reasonably good agreement with the transient modelling approach for coarse textured soils but tended to overestimate the travel time if a layer of fine textured soil was present near the surface. Thus, care should be taken when using the simplified methods to estimate vadose zone travel time and vulnerability of the underlying aquifers.
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Leon, Joseph Aristotle R. De, Ronnie S. Concepcion II, Robert Kerwin C. Billones, Jonah Jahara G. Baun, Jose Miguel F. Custodio, Ryan Rhay P. Vicerra, Argel A. Bandala, and Elmer P. Dadios. "Digital Twin Concept Utilizing Electrical Resistivity Tomography for Monitoring Seawater Intrusion." Journal of Advanced Computational Intelligence and Intelligent Informatics 27, no. 1 (January 20, 2023): 12–18. http://dx.doi.org/10.20965/jaciii.2023.p0012.
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Electrical resistivity tomography (ERT) has been seen as an appropriate instrument in several works to monitor and aid in the control of seawater intrusion (SWI) in coastal groundwater systems. This study seeks to discuss the synthesis of a digital twin that couples information between the physical space through ERT as a monitoring sensor and the digital space using SWI simulations to accurately model the behavior of SWI in the present and future settings. To showcase the concept, a Python-based simulation was presented that shows (a) the joint forward modeling-simulation scheme for calculating expected ERT apparent resistivity values from simulated SWI and (b) the calibration of the digital coastal aquifer system through genetic algorithm to accurately match the outputs of the SWI simulations with the ERT measurements.
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Clemo, Tom. "Coupled Aquifer-Borehole Simulation." Ground Water 48, no. 1 (January 2010): 68–78. http://dx.doi.org/10.1111/j.1745-6584.2009.00597.x.
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Ukaegbu, C., O. Gundogan, E. Mackay, G. Pickup, A. Todd, and F. Gozalpour. "Simulation of CO2 storage in a heterogeneous aquifer." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223, no. 3 (March 3, 2009): 249–67. http://dx.doi.org/10.1243/09576509jpe627.
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The fate of carbon dioxide (CO2) injected into a deep saline aquifer depends largely on the geological structure within the aquifer. For example, low permeability layers, such as shales or mudstones, will act as barriers to vertical flow of CO2 gas, whereas high permeability channels may assist the lateral migration of CO2. It is therefore important to include permeability heterogeneity in models for numerical flow simulation As an example of a heterogeneous system, a model of fluvial-incised valley deposits was used. Flow simulations were performed using the generalized equation-of-state model—greenhouse gas software package from Computer Modelling Group, which is a compositional simulator, specially adapted for CO2 storage. The impacts of residual gas and water saturations, gas diffusion in the aqueous phase, hysteresis, and permeability anisotropy on the distribution of CO2 between the gaseous and aqueous phases were examined. Gas diffusion in the aqueous phase was found to significantly enhance solubility trapping of CO2, even when hysteretic trapping of CO2 as a residual phase is taken into account.
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Yenigül, N. B., A. T. Hendsbergen, A. M. M. Elfeki, and F. M. Dekking. "Detection of contaminant plumes released from landfills." Hydrology and Earth System Sciences Discussions 3, no. 3 (June 6, 2006): 819–57. http://dx.doi.org/10.5194/hessd-3-819-2006.
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Abstract. Contaminant leaks released from landfills are a significant threat to groundwater quality. The groundwater detection monitoring systems installed in the vicinity of such facilities are vital. In this study the detection probability of a contaminant plume released from a landfill has been investigated by means of both a simulation and an analytical model for both homogeneous and heterogeneous aquifer conditions. The results of the two models are compared for homogeneous aquifer conditions to illustrate the errors that might be encountered with the simulation model. For heterogeneous aquifer conditions contaminant transport is modelled by an analytical model using effective (macro) dispersivities. The results of the analysis show that the simulation model gives the concentration values correctly over most of the plume length for homogeneous aquifer conditions, and that the detection probability of a contaminant plume at given monitoring well locations match quite well. For heterogeneous aquifer conditions the approximating analytical model based on effective (macro) dispersivities yields the average concentration distribution satisfactorily. However, it is insufficient in monitoring system design since the discrepancy between the detection probabilities of contaminant plumes at given monitoring well locations computed by the two models is significant, particularly with high dispersivity and heterogeneity.
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Vasco, D. W., and Gwyn Mali. "On the use of adjoints in the inversion of observed quasi-static deformation." Geophysical Journal International 224, no. 2 (October 23, 2020): 896–908. http://dx.doi.org/10.1093/gji/ggaa481.
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SUMMARY An adjoint-based conjugate gradient algorithm provides an efficient means for imaging sources of deformation within the Earth, such as volume stresses associated with fluid flow in aquifers and reservoirs. For time intervals over which the overburden deforms elastically, one can calculate the gradient elements for a single model update using just two numerical simulations. The first is a forward run that is used to compute the residuals associated with the given iteration. The second simulation is to evaluate the application of the adjoint operator to the residuals. In this adjoint calculation, the residual displacements are applied as sources at the measurement locations, driving the deformation in the simulation. The volume stress on the source grid blocks, in response to the residual displacements, provide the gradient components. We apply this technique to satellite-based interferometric synthetic aperture radar (InSAR) line-of-sight displacements that were observed over an oil reservoir in California’s Central Valley. We find that the adjoint-based gradient estimates, requiring 18 CPU seconds, agree with conventional numerical calculations that take over 3700 CPU seconds to compute. Conjugate gradient algorithms utilizing the conventional approach and adjoint-based gradient computations give roughly the same reductions in misfit and similar final estimates of reservoir volume change.
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Rongved, Mats, and Pierre Cerasi. "Simulation of Stress Hysteresis Effect on Permeability Increase Risk Along A Fault." Energies 12, no. 18 (September 7, 2019): 3458. http://dx.doi.org/10.3390/en12183458.
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CO2 sequestration projects will in the coming years include both aquifer and depleted oil and gas field sites, with different stress paths and history. Stress changes and stress concentration effects on faults will have to be readily assessed, potentially endangering shallower permeable formations. Usually, a fault is modeled as a singularity with shear strength or friction properties, and simulations are run to determine whether the fault is reactivated through shear failure. In this paper, we model a simple rectilinear fault as a finite surface with lowered mechanical properties compared to elsewhere in the domain, which represents a fractured zone alongside the fault core. SINTEF’s Modified Discrete Element code is used coupled to the flow simulator TOUGH2, to model the fracture initiation and propagation, monitoring the permeability increase along the fault. A simplified scenario is simulated, with a sandstone storage reservoir bounded by a fault, penetrating a shale caprock to a shallower sandstone layer. The storage site either undergoes depletion before CO2 injection or has its pore pressure increased to simulate the case of aquifer storage. Results show that during depletion, shear stresses may develop such that fractures propagate alongside the fault to the upper aquifer. However, for the mirror fault orientation with regards to verticality, no such fractures develop. These results are reversed for the aquifer storage case.
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Krause, M., J. C. C. Perrin, and S. M. M. Benson. "Modeling Permeability Distributions in a Sandstone Core for History Matching Coreflood Experiments." SPE Journal 16, no. 04 (January 6, 2011): 768–77. http://dx.doi.org/10.2118/126340-pa.
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Summary Saline-aquifer storage of carbon dioxide (CO2) has become recognized as an important strategy for climate-change mitigation. Saline aquifers have very large estimated storage capacities, are distributed broadly across the globe, and have the potential for geologic-scale retention times. Many of these storage sites are not well characterized, and it is critical to conduct detailed experiments and analysis to understand how features such as heterogeneity can influence the theoretical storage capacity, spatial extent of plume migration, and secondary trapping processes. Coreflooding experiments are used routinely by the oil and gas industry for such analysis and provide a very useful tool for studying saline-aquifer formations also. Numerical simulations of these coreflooding experiments can provide insight beyond the experimental measurements themselves, such as numerically studying how properties such as relative permeability and capillary pressure affect CO2 distribution in these systems under various flow conditions. However, accurate subcore-scale simulations of these experiments have remained a challenge, and the issue of how to represent subcorescale permeability has not been resolved previously. Laboratory coreflooding experiments injecting CO2 into a saline-water-saturated Berea sandstone core have been conducted at reservoir conditions. Computed-tomography (CT) scans of the core show large spatial variations of CO2 saturation, even within a relatively homogeneous core. Numerical simulations of the experiment have been conducted to study the effect of subcorescale heterogeneity and the role of permeability in determining the subcore-scale CO2 distribution in the core to explain these very large spatial variations in CO2 saturation. Numerical simulations of the experiment consistently showed that use of traditional methods for estimating subcore-scale permeability, typically based solely on porosity distributions, results in subcore-scale saturation distributions that do not match experimental measurements. In this paper, we develop a new method for calculating subcore-scale permeability distributions on the basis of capillary pressure measurements and porosity distributions as an alternative to the traditional porosity-only-based models. Using experimentally measured saturation and porosity distributions and capillary pressure data to calculate permeability, simulations based on this new method show a substantial improvement both in the absolute value and in the spatial distribution of predicted CO2-saturation values. With this technique for accurately calculating permeability distributions, it is possible to study subcore-scale multiphase flow of brine and CO2 to understand how small-scale heterogeneities influence the spatial distribution of CO2 saturation and to improve our ability to predict the fate of stored CO2.
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Bodin, Jacques. "MFIT 1.0.0: Multi-Flow Inversion of Tracer breakthrough curves in fractured and karst aquifers." Geoscientific Model Development 13, no. 6 (July 1, 2020): 2905–24. http://dx.doi.org/10.5194/gmd-13-2905-2020.
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Abstract. More than half of the Earth's population depends largely or entirely on fractured or karst aquifers for their drinking water supply. Both the characterization and modeling of these groundwater reservoirs are therefore of worldwide concern. Artificial tracer testing is a widely used method for the characterization of solute (including contaminant) transport in groundwater. Tracer experiments consist of a two-step procedure: (1) introducing a conservative tracer-labeled solution into an aquifer, usually through a sinkhole or a well, and (2) measuring the concentration breakthrough curve (BTC) response(s) at one or several downstream monitoring locations, usually spring(s) or pumping well(s). However, the modeling and interpretation of tracer test responses can be a challenging task in some cases, notably when the BTCs exhibit multiple local peaks and/or extensive backward tailing. MFIT (Multi-Flow Inversion of Tracer breakthrough curves) is a new open-source Windows-based computer package for the analytical modeling of tracer BTCs. This software integrates four transport models that are all capable of simulating single- or multiple-peak and/or heavy-tailed BTCs. The four transport models are encapsulated in a general multiflow modeling framework, which assumes that the spatial heterogeneity of an aquifer can be approximated by a combination of independent one-dimensional channels. Two of the MFIT transport models are believed to be new, as they combine the multiflow approach and the double-porosity concept, which is applied at the scale of the individual channels. Another salient feature of MFIT is its compatibility and interface with the advanced optimization tools of the PEST suite of programs. Hence, MFIT is the first BTC fitting tool that allows for regularized inversion and nonlinear analysis of the postcalibration uncertainty of model parameters.
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Herman, Marc E., Robert W. Buddemeier, and Stephen W. Wheatcraft. "A layered aquifer model of atoll island hydrology: Validation of a computer simulation." Journal of Hydrology 84, no. 3-4 (May 1986): 303–22. http://dx.doi.org/10.1016/0022-1694(86)90129-0.
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Lyons, Richard T., Richard C. Peralta, and 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, no. 3 (January 30, 2020): 853. http://dx.doi.org/10.3390/ijerph17030853.
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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.
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Sheets, Rodney A., Mary C. Hill, Henk M. Haitjema, Alden M. Provost, and John P. Masterson. "Simulation of Water-Table Aquifers Using Specified Saturated Thickness." Groundwater 53, no. 1 (February 6, 2014): 151–57. http://dx.doi.org/10.1111/gwat.12164.
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Szymkiewicz, Adam, Anna Gumuła-Kawęcka, Jirka Šimůnek, Bertrand Leterme, Sahila Beegum, Beata Jaworska-Szulc, Małgorzata Pruszkowska-Caceres, Wioletta Gorczewska-Langner, Rafael Angulo-Jaramillo, and Diederik Jacques. "Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW." Journal of Hydrology and Hydromechanics 66, no. 2 (June 1, 2018): 246–56. http://dx.doi.org/10.2478/johh-2018-0005.
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AbstractThe paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.
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Gaiolini, Mattia, Nicolò Colombani, Gianluigi Busico, Fabrizio Rama, and Micòl Mastrocicco. "Impact of Boundary Conditions Dynamics on Groundwater Budget in the Campania Region (Italy)." Water 14, no. 16 (August 9, 2022): 2462. http://dx.doi.org/10.3390/w14162462.
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Groundwater budgets and fluxes are affected by human activities and climate change. Numerical models are cost-effective tools to investigate the different components of the hydrologic cycle. In this study, a groundwater flow model of the unconfined aquifers of the Campania region (Italy) has been developed and calibrated in Processing Modflow 11, resulting in an accurate assessment of groundwater fluxes and their trends over fifteen years (2000–2015). The model was implemented using a high-resolution grid to capture small hydrogeological features such as wells and rivers and informed by time variable datasets used as boundary conditions (i.e., river and sea levels, aquifer recharge, evapotranspiration, and discharge from adjacent systems). Good calibration and validation performances were achieved for piezometric heads (R2 = 0.958). A set of scenarios was developed using constant boundary conditions (i.e., constant sea-level BC, uniform extinction depth BC), and the outputs were compared, quantitively assessing differences in groundwater fluxes. Simulations pointed out that using time series to inform boundary conditions in the model does not always result in a significant change in the computed fluxes. Overall, non-uniform extinction depth was the most influential condition, while both rivers and sea level conditions barely affected groundwater budgets. In addition, results highlighted the need for an accurate estimation of spatiotemporal variations of both recharge and evapotranspiration, due to their strong seasonal variability and their massive contribution to the hydrogeological cycle. Finally, a marked increase of evapotranspiration fluxes controlled by interannual variability of precipitation and atmospheric temperatures has been quantified over the modelled period.
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Mariethoz, Grégoire, Philippe Renard, Fabien Cornaton, and Olivier Jaquet. "Truncated Plurigaussian Simulations to Characterize Aquifer Heterogeneity." Ground Water 47, no. 1 (January 2009): 13–24. http://dx.doi.org/10.1111/j.1745-6584.2008.00489.x.
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Grünberger, O., J. L. Michelot, L. Bouchaou, P. Macaigne, Y. Hsissou, and C. Hammecker. "Capillary rise quantifications based on in-situ artificial deuterium peak displacement and laboratory soil characterization." Hydrology and Earth System Sciences 15, no. 5 (May 27, 2011): 1629–39. http://dx.doi.org/10.5194/hess-15-1629-2011.
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Abstract. In arid environments, water rises from the saturated level of a shallow aquifer to the drying soil surface where evaporation occurs. This process plays important roles in terms of plant survival, salt balance and aquifer budget. A new field quantification method of this capillary rise flow is proposed using micro-injections (6 μL) of a deuterium-enriched solution (δ value of 63 000‰ vs. V-SMOW) into unsaturated soil at a 1 m depth. Evaluation of peak displacement from profile sampling 35 days later delivered an estimate that was compared with outputs of numerical simulation based on laboratory hydrodynamic measurements assuming a steady state regime. A rate of 3.7 cm y−1 was estimated at a Moroccan site, where the aquifer water depth was 2.44 m. This value was higher than that computed from the relationship between evaporation rates and water level depth based on natural isotopic profile estimates, but it was lower than every estimate established using integration of the van Genuchten closed-form functions for soil hydraulic conductivity and retention curve.
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Munoz, Jose F., and Manuel J. Irarrazaval. "A Numerical Model for Simulation of Bioremediation of Hydrocarbons in Aquifers." Ground Water 36, no. 2 (March 1998): 215–24. http://dx.doi.org/10.1111/j.1745-6584.1998.tb01086.x.
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