• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.253-257
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• 2005

This research aims to demonstrate the regional and site scale groundwater flow simulation for the high level radioactive disposal research site in Yu-seong. We used the Modflow by a finite difference method for groundwater flow simulation, and Modpath module in Modflow package for particle tracking simulation. The range of numerical domain for regional groundwater flow model is $16.32km{\times}20.16km$. And, the depth of numerical domain was expanded to 6,000m. The area of numerical domain for the site scale groundwater flow simulation is $1.6km{\times}1.6km$. Since 2005, the underground research tunnel(URT) is being constructed at KAERI(Korea Atomic Energy Research Institute) site. In the site scale groundwater flow model, the groundwater flow around the KAERI site is simulated. And the change of groundwater level with tunnel excavation is also predicted.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.36-39
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• 2006

To evaluate the effect of groundwater flow on the outlet temperature of a geothermal heat pump, 3 dimensional numerical simulations are performed considering both groundwater flow and pipe flow in the U-tube using TOUGHS, The present study involved the following 4 simulation cases (1) no groundwater flow, (2) slow groundwater flow (hydraulic conductivity: $1.0{\times}10^{-9}m/s)$, (3) fast groundwater flow (hydraulic conductivity, $1.0{\times}10^{-7}m/s$), and (4) groundwater flow varying with the depth (hydraulic conductivity: $1.0{\times}10^{-7}-1.0{\times}10^{-10}m/s$). The effect of groundwater flow on the outlet temperature is significant where hydraulic conductivity of aquifer is $1.0{\times}10^{-7}m/s$. Where hydraulic conductivity of aquifer is $1.0{\times}10^{-10}m/s$, however, that effect is negligible.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.988-997
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• 2006

In this paper, a reliability-groundwater flow program is developed by coupling the 3-D finite element numerical groundwater flow program with first and second order reliability program. The numerical groundwater program developed called DGU-FLOW is verified by solving the examples of groundwater flow through the underground excavation and comparing the results with those of commercial MODFLOW 3D programs. Reliability routine of the program is also verified by comparing the probability of failure of the flow model from FORM/SORM with that of Monte-Carlo Simulation. The difference of out-flux and total head calculated near the bottom of the excavation using the deterministic 3D groundwater flow and the commercial programs was negligible. The reliability analysis of the groundwater flow showed that the probability of failure from the first and second order reliability method are quite close that of Monte-Carlo Simulation. Therefore, the developed program is considered effective for analyzing the groundwater flow with uncertainty in hydraulic conductivity of the soils.

• Proceedings of the Korea Water Resources Association Conference
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• 1987.07a
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• pp.113-122
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• 1987

A numerical simulation technique of three-dimensional finite difference model is developed to study the groundwater flow system in Dcjima, an upland area which faces Kasumigaura Lake. For general perspectives of the groundwater flow system, a steady state three-dimentional model is simulated. For the sedimentary mud formations which are found in the representative formation, three situations of hydraulic conductivity are considered, representing an isotropic condition and situations where the horizontal permeability is equal to 10 times and 100times of the vertical one. The finite difference grid used in the simulation has 60x50x30=90,000 nodes. A converged solution with a tolerance of 0.001 meter of hydraulic head is set. Having determined the flow net by using a steady state three-dimensional model. the results for the three cases of hydraulic conductivity are compared with the results of tracer methods (Bae and Kayane 1987) With the aid of four representative vertical cross-sections, groundwater flow systems in the study area are assumed. Water balances for the three cases indicate very good agreement between total recharge and discharge in each case Analyses of groundwater flow system based on the tritium concentrations and water quality measurements (Bae and Kayane 1987) are confirmed by the numerical simulation and the results obtained by these two methods appeared to be in close agreement.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.247-257
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• 2021

The study area has been contaminated with explosive materials and heavy metals for several decades. For the design of the pump and treat remediation method, groundwater flow before and during groundwater pumping in a contaminated aquifer system was simulated, calibrated, and predicted using a generalized multidimensional hydrological numerical model. A three-dimensional geologic formation model representing the geology, hydrogeology, and topography of the aquifer system was established. A steady-state numerical simulation with model calibration was performed to obtain initial steady-state spatial distributions of groundwater flow and groundwater table in the aquifer system before groundwater pumping, and its results were illustrated and analyzed. A series of transient-state numerical simulations were then performed during groundwater pumping with the four different pumping rates at a potential location of the pumping well. Its results are illustrated and analyzed to provide primary reference data for the pump and treat remediation method. The results of both steady-state and transient-state numerical simulations show that the spatial distribution and properties of the geologic media and the topography have significant effects on the groundwater flow and thus depression zone.

• Journal of Soil and Groundwater Environment
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• v.28 no.6
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• pp.9-15
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• 2023

In order to properly evaluate the spatio-temporal variations of groundwater flow, the data obtained in field experiments should be corroborated into numerical simulations. Particle tracking method is a simple simulation tool often employed in groundwater simulation to predict groundwater flow paths or solute transport paths. Particle tracking simulations visually show overall the particle flow path along the entire aquifer, but no previous simulation studies has yet described the parameter values at grid nodes around the particle path. Therefore, in this study, a new technical approach was proposed that enables acquisition of parameters associated with particle transport in grid nodes distributed in the center of the particle path in groundwater. Since the particle tracking path is commonly referred to as streamline, the algorithm and codes developed in this works designated streamline analysis method. The streamline analysis method can be applied in two-dimensional and three-dimensional finite element or finite difference grid networks, and can be utilized not only in the groundwater field but also in all fields that perform numerical modeling.

• Journal of Environmental Science International
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• v.28 no.12
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• pp.1157-1169
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• 2019

We used numerical models to reliably analyze the groundwater flow and hydraulic conductivity on Jeju Island. To increase reliability, improvements were made to model application factors such as hydraulic watershed classification, groundwater recharge calculation by precipitation, hydraulic conduction calculation using the pilot point method, and expansion of the observed groundwater level. Analysis of groundwater flow showed that the model-calculated water level was similar to the observed value. However, the Seogwi and West Jeju watersheds showed large differences in groundwater level. These areas need to be analyzed by segmenting the distribution of the hydraulic conductivity. Analyzing the groundwater flow in a sub watershed showed that groundwater flow was similar to values from equipotential lines; therefore, the reliability of the analysis results could be improved. Estimation of hydraulic conductivity distribution according to the results of the groundwater flow simulation for all areas of Jeju Island showed hydraulic conductivity > 100 m/d in the coastal area and 1 - 45 m/d in the upstream area. Notably, hydraulic conductivity was 500 m/d or above in the lowlands of the eastern area, and it was relatively high in some northern and southern areas. Such characteristics were found to be related to distribution of the equipotential lines and type of groundwater occurrence.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.435-446
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• 2020

The use of groundwater in Korea has increased in recent years to the point where its extraction is restricted in times of drought. This work models the groundwater pumping field as a confined aquifer in a simplified simulation of groundwater flow. It proposes a genetic algorithm to maximize groundwater development using a conceptual model of a steady-state confined aquifer. Solving the groundwater flow equation numerically calculates the hydraulic head along the domain of the problem; the algorithm subsequently offers optimized pumping strategies. The algorithm proposed here is designed to improve a prior initial groundwater management model. The best solution is obtained after 200 iterations. The results compare the computing time for five simulation cases. This study shows that the proposed algorithm can facilitate better groundwater development compared with a basic genetic algorithm.

• Journal of Environmental Impact Assessment
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• v.16 no.4
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• pp.251-265
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• 2007

In this study, the influence of the construction of a large sized building on the flow and level of groundwater in a metropolitan area was investigated with simulation model MODFLOW for a selected area located in Gangseo-gu, Seoul, where a large business center was scheduled to be built. It was simulated that the groundwater level in the study area was suddenly lowered by the construction of a large building and groundwater in the surrounding area fast flowed into the study area. And even after the construction finished, the falling down of groundwater level consistently continued in some degree. The flow state of groundwater appeared to be the same in both cases where a soil cement wall is applied and where it is not during the construction. But for the case of application of a soil cement wall as the amount of groundwater flowing into the study site became reduced, it was estimated that the time for underground watershed getting far away from the site was also reduced and the influence of a building construction on the surrounding groundwater became reduced. Thus, it is deemed necessary that recharging the spilled ground water and rainfall into the construction area to lessen the abrupt change in flow and level of ground water should be considered in design of construction of a large sized building in a metropolitan area.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.69-76
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• 2006

A reliability-groundwater flow analysis is performed and the influence of flow parameters on the probability of exceeding the threshold value is examined. For this study, the 3-D numerical groundwater flow program, DGU-FLOW, is developed by extending the 2-D flow program and is coupled to the first and second order reliability program. The 3-D flow program is verified by solving the examples of groundwater flow through the underground excavation and comparing the results from commercial MODFLOW program. Reliability routine of the program is also verified by comparing the probability of failure with that of Monte-Carlo Simulation. The reliability analysis of the groundwater flow showed that the probability of failure from the first and second order reliability method are quite close to that of Monte-Carlo Simulation. from the parametric study of hydraulic conductivity of soil layers, the increase of both mean and variance of hydraulic conductivity results in the increase of probability of exceeding the threshold flow quantity. The probability of failure was more sensitive to constant head located at the end of the flow domain than the other parameters.