• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.1-9
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• 2017

The numerical analysis of groundwater flow is indispensable for predicting problems associated with water resource development, civil works, environmental hazards, and nuclear power plant construction. Korea lacks public regulatory procedures and guidelines for groundwater flow modeling, especially in nuclear facility sites, which makes adequate evaluation difficult. Feasible step-by-step guidelines are also unavailable. Consequently, reports on groundwater flow modeling have low-grade quality and often present controversial opinions. Additionally, without public guidelines, maintaining consistency in reviewing reports and enforcing laws is more challenging. In this study, the guidelines for groundwater flow modeling were reviewed for three countries - the United States (Documenting Groundwater Modeling at Sites Contaminated with Radioactive Substances), Canada (Guidelines for Groundwater Modelling to Assess Impacts of Proposed Natural Resource Development Activities), and Australia (Australian Groundwater Modelling Guidelines), with the aim of developing groundwater flow modeling regulatory guidelines that can be applied to nuclear facilities in Korea, in accordance with the Groundwater Act, Environmental Impact Assessment Act, and the Nuclear Safety Act.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.536-539
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• 2003

This study area has been contaminated by oils. To identify contaminated ranges and to assess the possibility of contamination dispersion, monitoring wells were installed and slug test, field soil permeability test, automatic or manual measurement of groundwater table, and groundwater quality analyses in field and laboratory were performed. In addition, a groundwater modeling program was used to assess the possibility of oil contamination dispersion, based on field data and groundwater quality data. The results showed that concentration of oil contaminants in groundwater have been decreased by dispersion and adsorption.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.81-99
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• 2018

Excessive groundwater discharge by tunneling and tunnel operation can lead to groundwater exhaustion and ground subsidence. Therefore, it is very important to evaluate environmental impact and to establish mitigation measures of the impact related to tunnel excavation based on hydrogeological and modeling approaches. This study examined the depletion of surface reservoirs and valley water due to tunnel excavation through field survey, water quality analysis, tracer test, and groundwater modeling. As a result of field water quality test, the concentration of chemical constituents in groundwater discharge into the tunnel is slightly higher than that of valley water. By the result of laboratory water analysis, both valley water and the groundwater belong to $Ca^{2+}+HCO_3{^-}$ type. Tracer test that was conducted between the valley at the injection point and the tunnel, indicates valley water infiltration into the ground and flowing out to the tunnel, with maximum electrical conductance changes of $70{\mu}S/cm$ in the first test and of $40{\mu}S/cm$ in the second test. By groundwater modeling, the groundwater discharge rate into the tunnel during tunnel construction is estimated as $4,942m^3/day$ and groundwater level recovers in 3 years from the tunnel completion. As a result of particle tracking modeling, the nearest particle reaches the tunnel after 6 hours and the farthest particle reaches the tunnel after 9 hours, similarly to the case of the field trace test.

• Journal of the Korean Society of Groundwater Environment
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• v.2 no.1
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• pp.9-13
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• 1995

In the stream-aquifer setting, this study evaluated the effects of spatial variability in nonpoint sources and hydraulic conductivity on groundwater outflow concentration history. Monte Carlo experiments based on the advection-dispersion equation were used to determine the statistical moments of groundwater outflow concentration history. The comparison between a spatially distributed model and spatially integrated model (SID) was made in order to examine the possibility of applying SID to the problems of nonpoint source groundwater pollution.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.287-287
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• 2023

Surface water-groundwater interaction (SWGI) is an important hydrological process that influences both the quantity and quality of water resources. However, regional scale SWGI model calibration and uncertainty analysis have been a challenge because integrated models inherently carry a vast number of parameters, modeling assumptions, and inputs, potentially leaving little time and budget to explore questions related to model performance and forecasting. In this study, we have proposed the application of iterative ensemble smoother (IES) for uncertainty analysis and calibration of the widely used integrated surface-subsurface model, SWAT-MODFLOW. SWAT-MODFLOW integrates Soil and Water Assessment Tool (SWAT) and a three-dimensional finite difference model (MODFLOW). The model was calibrated using a parameter estimation tool (PEST). The major advantage of the employed IES is that the number of model runs required for the calibration of an ensemble is independent of the number of adjustable parameters. The pilot point approach was followed to calibrate the aquifer parameters, namely hydraulic conductivity, specific storage, and specific yield. The parameter estimation process for the SWAT model focused primarily on surface-related parameters. The uncertainties both in the streamflow and groundwater level were assessed. The work presented provides valuable insights for future endeavors in coupled surface-subsurface modeling, data collection, model development, and informed decision-making.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1494-1501
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• 2008

Recently, the demand of water resources is constantly increasing due to the substantial increase of population, economy, and living standard. However, it is expected that the water resources should undergo serious problems of poor quality of water as well as shortage of water supply in the near future. Additionally, thoughtless groundwater development have caused to dry river and stream. In this study, the effectiveness of dry stream protection plan is evaluated by using 3-D groundwater flow modeling for the study area which is located in Namyangju of Kyoungi Province. Aquifer tests are performed to obtain the input data of the model. To analyze causes of dry stream using modeling results that water balance is analyzed for situations of before and after closing the wells.

• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.29-37
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• 2007

Shallow alluvial groundwaters in Korea of tell exceed the Korean Drinking Water Standard for dissolved iron (0.3 mg/L), which is one of the important water quality problems, especially in the use of bank infiltration technique. Using the reactive transport modeling, in this study we simulated the effectiveness of injection-and-pumping technique to remove dissolved iron in groundwater. The results of simulation showed that pumping of groundwater after injection of oxygenated water into aquifers is very effective to acquire the permissible water quality level. Groundwater withdrawal up to several times of irjected water in volume can be applicable to yield drinkable water. Potential problems such as clogging and permeability lowering due to in-situ precipitation of iron hydroxides may be insignificant. We also discuss on the mechanism and spatial extent of iron removal in aquifer.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.4
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• pp.273-281
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• 2007

Hyperalkaline groundwater formed by groundwater-cement components and its reaction with bedrock in a nuclear waste repository were simulated by geochemical modeling. The result of groundwater-cement components reaction showed that the pH of water was 13.3 and the precipitated minerals were Brucite, Katoite, Calcium Silicate Hydrate(CSH1.1), Ettringite, Hematite, and Portlandite. The result of interaction between such minerals and groundwater sampled in Gyeongju area also showed that the pH of groundwater reached 12.4. Interaction between such hyperalkaline groundwater and granite was simulated by kinetic model during $10^3$ years. This result showed that the final pH of groundwater reached 11.2 and the variation of pH was controlled by dissolution/precipitation of silicate and CSH minerals. Groundwater quality was also determined by dissolution/precipitation of silicate, CSH, oxide minerals. Our results show that geochemical modeling of long-term hyperalkaline groundwater and rock interaction can contribute to the safety assessment of engineered barrier by predicting geochemical condition in repository site.

• Journal of Environmental Science International
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• v.27 no.10
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• pp.831-844
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• 2018

Riverbank Filtration (RBF) is a kind of indirect artificial recharge method and is useful in obtaining higher-quality source water than surface water when procuring municipal water. This study evaluated optimal riverbank filtered water and the productivity of the radial collector wells on Ttansum Island in the area downstream of the Nakdong River, where Gimhae City is constructing a municipal water plant for the purpose of acquiring high-quality water. The RBF wells are planned to provide water to the citizens of Gimhae City through municipal water works. Groundwater flow modeling was performed with the following four scenarios: (a) 9 radial collector wells, (b) 10 radial collector wells, (c) 10 radial collector wells and two additional vertical wells, and (d) 12 radial collector wells. This study can be useful in determineing the optimum production rate of bank filtrated water not only in this study area but also in other places in Korea.

• Economic and Environmental Geology
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• v.37 no.5
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• pp.499-508
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• 2004

Changwon City first constructed riverbank filtration plants in Book-Myeon and Daesan-Myeon in Korea in the year 2001. This study evaluated hydrogeological characteristics and groundwater flow simulation between the Nakdong River and the fluvial aquifers adjacent to the river in Book-Myeon, Changwon City. The groundwater simulation calculated the influx rate from the Nakdong River and the fluvial aquifers to pumping wells through the riverbank filtration system. The groundwater flow model utilized drilling, grain size analysis, pumping test, groundwater level measurements, river water discharge and rainfall data. Hydraulic heads calculated by the steady-state model closely matched measured heads in pumping and observation wells. According to the transient flow model, using a total pumping amount of 14,000 $m^3$/day, the flux into the pumping wells from the Nakdong River accounts for 8,390 $m^3$/day (60%), 590 $m^3$/day (4%) is from the aquifer in the rectilinea. direction to the Nakdong River, and 5,020 $m^3$/day (36%) is from the aquifer in the parallel direction to the Nakdong River. The particle tracking analysis shows that a particle from the Nakdong River moves toward the pumping wells at a rate of about 1.85 m/day and a particle from the aquifer moves toward the pumping wells at a rate of about 0.75 m/day. This study contributes to surface water/groundwater management modeling, and helps in understanding, how seasonal change affects pumping rates, water quality, and natural recharge.