• Economic and Environmental Geology
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• v.47 no.6
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• pp.625-633
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• 2014

The Aquistore project is the world's first commercial capture, transportation, utilization and storage project of post-combustion $CO_2$ from a coal-fired thermo electric power plant, and the proposed storage is a saline aquifer at a depth of about 3,500 m. Deep saline aquifer, compared to hydrocarbon reservoir, provides the great volumetric potential for storage of $CO_2$ anywhere in the world, therefore the research results from the project may be exported globally to other sites. Geological $CO_2$ storage characterization for saline aquifer instead of hydrocarbon reservoir needs to estimate the geophysical properties of subsurface geology. This study calculated the geophysical property of water-saturated formation by applying amplitude variation analysis developed from oil and gas exploration. We correlated horizon tops at the well logs to seismic traveltime of 1,815 and 1,857 ms as Winnipeg and Deadwood formations. Gradient analysis from seismic traces showed correlation coefficient of 45 - 81 % on amplitude variation with respect to incident angle. Crossplot of intercept and gradient shows the inverse proportional trend which represents typical water saturated sediments. Product attribute of intercept and gradient described the base of wet sediment. Poisson's ratio change attribute increased at the top of target area satisfying with wet sediment and decreased at the top of basement in a dry rock bed.

• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.152-157
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• 1999

Oil leaked from underwound storage tanks and leachate from sanitary landfills have been known as contaminant sources of the high-quality groundwater resources. The mobility of contaminants in the aquifer largely depends on the groundwater flow and the determination of associated hydraulic parameters is essential for a proper remediation of contaminated grnundwater. This study aimed at determining an optimum set of hydraulic parameters for an unconfined sandy aquifer of a laboratory scale through comparison of various methods. Results showed that the specific yield obtained from gravity drainage experiment was an average of 0.20 with minor variations in aquifer depths. and the permeabilities obtained from Dupuit approximation and slug test gave similar values of 5.33 cm/min and 5.85 cm/min but the constant head method gave 0.17 cm/min, which is much ion than the other methods. This experimental evidence reveals that the permeability of the unconfined sandy aquifer could be accurately determined by Dupuit assumption or slug tut rather than by constant head method conducted for a disturbed separate soil column.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.279-288
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• 2019

The groundwater drawdown at each monitoring well near a radial collector well along Anseong Stream, Korea, was measured and compared with the calculated drawdown using the mirror well concept. The drawdown calculation is performed by treating the collector well as a large vertical well in a homogeneous isotropic aquifer. The measured drawdown at each monitoring well is slightly different from the calculated value due to anisotropy in the hydraulic conductivity and aquifer thickness. The difference between the measured and calculated values at Well OW-7 is large, reaching approximately 48 cm, because a horizontal well is not installed along this direction. Sensitivity analysis of the hydraulic conductivity and aquifer thickness indicates that the hydraulic conductivity is more sensitive to groundwater level changes. Groundwater level changes become a concern when a radial collector well with a large pumping rate capacity is installed, which highlights the need to thoroughly investigate the aquifer characteristics in the surrounding area.

• The Journal of Engineering Geology
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• v.29 no.3
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• pp.303-314
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• 2019

Surface permeability and shallow geological structures play significant roles in shaping the groundwater recharge of shallow aquifers. Surface permeability can be characterized by two concepts, intrinsic permeability and hydraulic conductivity, with the latter obtained from previous near-surface geological investigations. Here we propose a hydraulic equation via the cross-correlation analysis of the rainfall-groundwater levels using a regression equation that is based on the cross-correlation between the grain size distribution curve for unconsolidated sediments and the rainfall-groundwater levels measured in the Gyeongju area, Korea, and discuss its application by comparing these results to field-based aquifer test results. The maximum cross-correlation equation between the hydraulic conductivity derived from Zunker's observation equation in a sandy alluvial aquifer and the rainfall-groundwater levels increases as a natural logarithmic function with high correlation coefficients (0.95). A 2.83% difference between the field-based aquifer test and root mean square error is observed when this regression equation is applied to the other observation wells. Therefore, rainfall-groundwater level monitoring data as well as aquifer test are very useful in estimating hydraulic conductivity.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.255-261
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• 2018

The purpose of this study was to obtain a large amount of saline groundwater around coastal aquaculture farms. Thus, we have proposed a method for evaluating the potential amount of saline groundwater resources through the combined analysis of geophysical methods. Refraction seismic survey and electrical resistivity survey were conducted in the vicinity of fish farm at Hadong, Gyeongnam Province. As the result, the velocity of layer in the range of 900 ~ 2,400 m/s was found to be saltwater aquifer with high water content. Geological drilling investigation and analysis of soil samples also showed that the soil at study area was the same as the texture of sandy loam layer in agricultural radial collector wells installed by KRC (Korea Rural Community Corporation). Futhermore, the study area turned out to be quite possible to develop saline groundwater from the coastal shallow aquifer. Therefore, parallel analysis of refraction seismic surveys and electrical resistivity surveys at coastal area are expected to be very useful for the detection of the aquifer composed of sand and gravel layers with high porosity in sandy sedimentary layers along the coastal area.

• Journal of the Korean Geotechnical Society
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• v.23 no.11
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• pp.99-107
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• 2007

The linear curve fitting methods such as the Hvorslev method and the Bouwer and Rice method provide a rapid and simple means to analyze slug test data for estimating in-situ hydraulic conductivity (k) of geologic material. However, when analyzing a slug test in a relatively compressible aquifer, these methods have difficulties in fitting a straight line to the semi-logarithmic plot of the test data that shows a concave-upward curvature because the linear curve fitting methods ignore the role of the compressibility or specific storage ($S_s$) of an aquifer. The comparison of the Hvorslev method and the Bouwer and Rice method is made far a partially-penetrating well geometry to show analytically that the Hvorslev method estimates higher hydraulic conductivity than the Bouwer and Rice method except that the well intake section locates very close to the bottom of the aquifer. The effect of fitting a straight line to the slug test data is evaluated along with the dimensionless compressibility parameter (${\alpha}$) ranging from 0.001 to 1. A modified linear curve fitting method that is expanded from Chirlin's approach to the case of a partially penetrating well with the basic-time-lag fitting method is introduced. A case study for a compressible glacial till is made to verify the proposed method by comparing with a type curve method (KGS method).

• Ecology and Resilient Infrastructure
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• v.11 no.2
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• pp.23-34
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• 2024

Sediment, aquifer materials, surface water, and groundwater from brackish Songji lake affected by salinity of seawater, were collected and a pilot scale column experiment was conducted to simulate the nitrogen transport through the hyporheic zone. Upstream experiments of groundwater displayed that groundwater containing a small amount of salt percolated into aquifers and sediments, maintaining low dissolved oxygen concentrations. In addition, partial denitrification occurred in the aquifer due to salinity and low dissolved oxygen, resulting in the accumulation of NO₂^-. In sediments,nitrogenous compounds were reduced due to adsorption by long residence times or microbial-mediated oxidation/reduction reactions. Downstream experiments of surface water displayed that surface water from the brackish lake, containing high concentrations of dissolved oxygen and salts, infiltrated into the sediments and aquifer, supplying high dissolved oxygen concentrations. This resulted in biological nitrification in the sediments and aquifer, which reduced nitrogen-based pollutants despite the high salt concentration in the surface water. Whereas partial denitrification at low dissolved oxygen concentrations in the upwelling mixing zone was observed by salinity and accumulated NO₂^-, nitrification at high dissolved oxygen concentrations in the downwelling mixing zone was not significantly affected by salinity. These results confirm that salinity in the brackish water lake has some influence on the nitrogen behavior of the hyporheic mixing zone, although nitrogen behavior is a complex combination of factors such as DO, pH, substrate concentration, and organic matter concentration.

• Journal of Soil and Groundwater Environment
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• v.7 no.2
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• pp.53-61
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• 2002

An Aquifer test was carried out on five boreholes to determine the hydrologic anisotropy and the major groundwater flow direction in the aquifer system of the study area. With an assumption of the aquifer's anisotropy and homogeneity, the major transmissivity(T(equation omitted)), the minor transmissivity( $T_{ηη}$ ), and primary tensor direction ($\theta$) for each borehole were determined from the test. Besides the boreholes BH-1, BH-4 and BH-5, the anisotropy transmissivity tensor values of BH-2 and BH-3 did not correspond with the assumption. Thereafter the values were plotted on the polar coordinate, and showed that the tensor values were out of the anisotropy ellipsoid due to the high heterogeneity of BH-2 and BH-3 comparing with the other boreholes. Therefore. the anisotropy of the aquifer was examined from BH-1, BH-4. and BH-5. In BH-1, T(equation omitted) is 171.9 $\m^2$/day. $T_{ηη}$ is $71.01\m^2$/day, and the principal tensor direction is Nl5.39$^{\circ}$E. In BH-4. T(equation omitted) is $268.2 \m^2$/day, $T_{ηη}$ / is $28.75\m^2$/day and the principal tensor direction is N7.55$^{\circ}$E. In BH-5, T(equation omitted) is $168.4\m^2$/day, $T_{ηη}$ is 66.80 $\m^2$/day, and the principal tensor direction is $N76.59^{\circ}$E. On the basis of teleview logging performed on each borehole. the principal fracture directions were revealed as $N0^{\circ}$~4$^{\circ}$E/$30^{\circ}$~$50^{\circ}$SE and $N30^{\circ}$~$80^{\circ}$W/$20^{\circ}$~$50^{\circ}$NE that are the most frequently occurred sets as well as that correspond well with the calculated transmissivity tensor.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.65-70
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• 2009

Reduction of groundwater surface tension prior to air sparging (SEAS, surfactant-enhanced air sparging) was known to increase air saturation in the aquifer under influence, possibly enhancing the removal rates of volatile contaminants. Although SEAS was known to be efficient for increasing air saturation, little information is available for different hydrogeological settings including soil particle sizes and the depth of aquifer. We investigated water saturations in the sparging influence zone during SEAS using one-dimensional column packed with sands of different particle sizes and different aquifer depths. An anionic surfactant was used to suppress the surface tension of water. Two different sands were used; the air entry pressures of the sands were measured to be $15.0\;cmH_2O$, and $36.3\;cmH_2O$, respectively. No significant difference was observed in the water saturation-surface tension relationship for sands with different particle sizes. As the surface tension decreased, the water saturation decreased to a lowest point and then it increased with further decrease in the surface tension. Both sands reached their lowest water saturations when the surface tension was set approximately at 42 dyne/cm. SEAS was conducted at three different aquifer depths; 41 cm, 81 cm, and 160 cm. Water saturation-surface tension relationship was consistent regardless of the aquifer depth. The size of sparging influence zone during SEAS, measured using two-dimensional model, was found to be similar to the changes in air saturation, measured using one-dimensional model. Considering diverse hydrogeological settings where SEAS to be applied, the results here may provide useful information for designing SEAS process.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.05a
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• pp.27-36
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• 2003