• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.453-454
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• 2004

Hydrogeochemical and isotopic characteristics were investigated for groundwater of Tertiary basin in southeastern part of Korea where deep drilling is in progress for geothermal investigation. According to geology, aquifer was distinguished as alluvial, tertiary sedimentary bedrock (bedrock groundwater), and fractured volcanic rock (deep groundwater). Groundwater of each aquifer is distinctively separated in Eh-pH conditions and concentrations of Cl, F, B and HCO$_3$. Deep groundwater has very low level 3H and 14C whereas alluvial groundwater has those of recent precipitation level. However one of deep groundwater show mixed characteristics in terms of hydrochemistry which indicates effect of pumping. Deep groundwater have temperature of 38 to 43$^{\circ}C$ whereas bedrock and alluvial groundwater have temperature less than 2$0^{\circ}C$. Fractured basement rock aquifer has different hydrogeologicalsetting from bedrock and alluvial aquifer considering hydrogeochemical and isotopic characteristics, and temperature.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.487-491
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• 2004

For tile hydrogeological data of the National Groundwater Monitoring Wells(NGMW), a statistical analysis is made to reveal aquifer characteristics of the country. Results of the pumping and recovery test are classified into 4～5 types by the pattern of drawdown and residual drawdown curves. The analysis of aquifer characteristics shows that the hydraulic conductivity of alluvial aquifers is greater than that of fractured-rock aquifers. The hydraulic conductivity of alluvial aquifers slightly increases as the distance to the discharge area decreases. 77.5% of the NGMWs, where the distance to the discharge area is more than 100m, shows the constant head boundary. This result suggests that the fractured and the alluvial aquifers are fairly interconnected, and water can be supplied from one aquifer to tile other where pumping tests are performed. It is analyzed that the wells showing the impermeable boundary are influenced by small scale of aquifers, poor aquifer transmissivities, and impermeable layers.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.287-291
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• 2003

To delineate the internal structures of alluvial aquifer, high resolution seismic and GPR methods were adopted in Buyeo Gunsu-Ri area. The result of seismic refraction survey shows the water table of the aquifer and the result of seismic reflection reveals the basement and somewhat dominant internal structures of alluvial aquifer. The internal heterogeneity due to variations in channel behavior can be delineated using GPR survey. GPR profiles for the point bar deposits near Buyeo county reveals two different stratigraphic units the lower inclined heterogeneous strata and the upper horizontally stratified strata. According to the increase of demand for water resource using artificial recharge in alluvium, it is believed that the information acquired by high resolution geophysical methods will have an important roles for the effective and sustainable development and usage of groundwater in alluvial aquifer.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.3
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• pp.1-7
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• 2018

In this paper, we designed a seasonal geothermal storage system and studied the applicability in the alluvial aquifer. We conducted a basic survey to apply this system to greenhouses actually operated in the Geum river basin alluvial aquifer. After choosing a potential area through electrical resistivity survey, the system parameters were set using drilling survey and pumping test result. We installed a system based on the factors, and operated for about 9 months. As a result, high temperature water(injection temperature $30^{\circ}C$) was stored at 22.5 Mcal ($1,609m^3$) for 3 months in cooling operation and 125 Mcal ($16,960m^3$) of low temperature water (injection temperature $7^{\circ}C$) were stored for 6 months in the remaining heating operation.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.97-99
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• 2004

To understand the geochemical processes controlling the distribution of nitrate and other agricultural constituents in an alluvial aquifer, hydrogeological and hydro geochemical studies were carried out in an agricultural area within Cheonan. In this selected field, nitrate concentrations were very wide in range but was locally attenuated significantly down to very low levels (<1.0 mg/L). Abrupt removal of nitrate coincided with the pattern of redox change and thus indicated that geochemical processes occurring during and after recharge events control the behavior and distribution of nitrate and other redox-sensitive chemical species.

• Journal of Soil and Groundwater Environment
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• v.25 no.1
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• pp.12-24
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• 2020

This study was conducted to examine an artificial recharge system, which was considered to be an alternative for securing additional groundwater resources in a high-density greenhouse region. An injection well with a depth of 14.0 m was placed in an alluvial plain of the zone. Eight monitoring wells were placed in a shape of dual circles around the injection well. Aquifer tests showed that the aquifer was comprised with high-permeable layer with hydraulic conductivities of 1.5×10^-3~2.4×10^-2 cm/sec and storage coefficients of 0.07~0.10. A step injection test resulted in a specific groundwater-level rising (Sr/Q) values of 0.013~0.018 day/㎡ with 64~92% injection efficiencies. Results of the constant-rate injection test with an optimal injection rate of 100 ㎥/day demonstrated an enormous storage capacity of the alluvial aquifer during ten experimental days. To design an optimal recharge system for an artificial recharge, the high-permeable layer should be isolated by dual packers and suitable pressure should be applied to the injection well in order to store water. An anisotropy ratio of the alluvial aquifer was evaluated to be approximately 1.25 : 1 with an anisotropy angle of 71 degrees, indicating intervals among injection wells are almost the same.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.389-394
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• 2008

The purpose of this research was to develop a methodology to determine whether conjunctive surface water and groundwater management could significantly reduce deficits in a river basin with a relatively limited alluvial aquifer. The Geum River basin is one of major river basins in South Korea. The upper region of the Geum River basin is typical of many river basins in Korea where the shape of river basin is narrow with small alluvial aquifer depths from 10m to 20m and where most of the groundwater pumped comes quickly from the steamflow. The basin has two surface reservoirs, Daecheong and Yongdam. The most recent reservoir, Yongdam, provides water to a trans-basin diversion, and therefore reduces the water resources available in the Geum River basin. After the completion of Yongdam reservoir, the reduced water supply in the Geum basin resulted in increasing conflicts between downstream water needs and required instream flows, particularly during the low flow season. Historically, the operation of groundwater pumping has had limited control and is administered separately from surface water diversions. Given the limited size of the alluvial aquifer, it is apparent that groundwater pumping is essentially taking its water from the stream. Therefore, the operation of the surface water withdrawals and groundwater pumping must be considered together. The major component of the conjunction water management in this study is a goal-programmin g based optimization model that simultaneously considers surface water withdrawals, groundwater pumping and instream flow requirements. A 10-day time step is used in the model. The interactions between groundwater pumping and the stream are handled through the use of response and lag coefficients. The impacts of pumping on streamflow are considered for multiple time periods. The model is formulated as a linear goal-programming problem that is solved with the commercial LINGO optimization software package.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.371-374
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• 2006

To quantify the hydraulic connection between river and aquifer, riverbed leakance values are required to be estimated. Silt, clay, and organic materials are often deposited in rivers resulting in the streambed having a lower hydraulic conductivity than the underlying alluvial aquifer The riverbed hydraulic conductivities are measured through vertical and oblique permeameter test. Anisotropic and heterogeneous properties of riverbed hydraulic conductivity were identified. Grain size analysis and flood wave response technique were checked along with the permeameter test for the riverbed hydraulic conductivity.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.6
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• pp.127-135
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• 2017

In this study, a cold well and a warm one with the distance of 100 m were installed in the alluvial aquifer. Groundwater used as the heat and the cold source of heat pump was designed to flow into the warm and the cold well with a diameter of 200 mm. In order to increase the heat and cold storage in aquifer, six auxiliary wells with the diameter of 50 mm and the depth of 30 m were installed at an interval of 5 m from the main well. Also, heat pump 50 RT, the thermal tank $40m^3$, and a remote control and monitoring system were installed in three single-span greenhouses ($2,100m^2$) for growing tomato in Buyeo, Chungcheongnam-do. According to the aquifer heat storage test which had been conducted from Aug. 31 to Sep. 22, 2016, warm water of $850m^3$ was found to flow into warm well. The temperature of the injected water was $30^{\circ}C$ (intake temperature : $15^{\circ}C$), and the heat of 12.8 Gcal was stored. The greenhouse heating test in winter had been conducted from Nov. 21, 2016 to Apr. 30, 2017. On Nov. 21, 2016 when heating greenhouse started, the aquifer temperature of the warm well was $18.5^{\circ}C$. The COP for heating with water source at $18.5^{\circ}C$ was 3.8. The intake water temperature of warm well was gradually lowered to the temperature of $15^{\circ}C$ on Jan. 2, 2017 and the heat pump COP was measured to be 3.2 at that time. As a result, the heat pump COP was improved by 18 %. and retrieval heat was 8 Gcal, the retrieval rate of heat stored in aquifer was estimated at 63 %.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.287-290
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• 2002

To examine the denitrification process in an alluvial aquifer in the Cheonan site, hydrological and hydrogeochemical studies were carried out. Elevated levels of NO$_3$ (maximum 77.6 mg/L) were observed in shallow groundwaters of the area, as a result of poultry and agricultural activity. However, the nitrate concentrations were found to be consistently attenuated down to very low levels (<1.0 mg/L). The abrupt removal of nitrate coincided with the pattern of redox change and indicated that denitrification is the most plausible process. The hydrochemistry and mass balance approach using geochemical modeling (phreeqc 2.0) and redox chemistry indicated that chemo-autotrophic denitrification via pyrite oxidation is the key Process to control the nitrate attenuation in the study area.